Commit graph

1363 commits

Author SHA1 Message Date
Linus Torvalds
8e8f6b635f - Prevent a futex hash leak due to different mm lifetimes
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Merge tag 'locking_urgent_for_v6.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fix from Borislav Petkov:

 - Prevent a futex hash leak due to different mm lifetimes

* tag 'locking_urgent_for_v6.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Move futex cleanup to __mmdrop()
2025-08-10 08:11:39 +03:00
Linus Torvalds
da23ea194d Significant patch series in this pull request:
- The 4 patch series "mseal cleanups" from Lorenzo Stoakes erforms some
   mseal cleaning with no intended functional change.
 
 - The 3 patch series "Optimizations for khugepaged" from David
   Hildenbrand improves khugepaged throughput by batching PTE operations
   for large folios.  This gain is mainly for arm64.
 
 - The 8 patch series "x86: enable EXECMEM_ROX_CACHE for ftrace and
   kprobes" from Mike Rapoport provides a bugfix, additional debug code and
   cleanups to the execmem code.
 
 - The 7 patch series "mm/shmem, swap: bugfix and improvement of mTHP
   swap in" from Kairui Song provides bugfixes, cleanups and performance
   improvememnts to the mTHP swapin code.
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Merge tag 'mm-stable-2025-08-03-12-35' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull more MM updates from Andrew Morton:
 "Significant patch series in this pull request:

   - "mseal cleanups" (Lorenzo Stoakes)

     Some mseal cleaning with no intended functional change.

   - "Optimizations for khugepaged" (David Hildenbrand)

     Improve khugepaged throughput by batching PTE operations for large
     folios. This gain is mainly for arm64.

   - "x86: enable EXECMEM_ROX_CACHE for ftrace and kprobes" (Mike Rapoport)

     A bugfix, additional debug code and cleanups to the execmem code.

   - "mm/shmem, swap: bugfix and improvement of mTHP swap in" (Kairui Song)

     Bugfixes, cleanups and performance improvememnts to the mTHP swapin
     code"

* tag 'mm-stable-2025-08-03-12-35' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (38 commits)
  mm: mempool: fix crash in mempool_free() for zero-minimum pools
  mm: correct type for vmalloc vm_flags fields
  mm/shmem, swap: fix major fault counting
  mm/shmem, swap: rework swap entry and index calculation for large swapin
  mm/shmem, swap: simplify swapin path and result handling
  mm/shmem, swap: never use swap cache and readahead for SWP_SYNCHRONOUS_IO
  mm/shmem, swap: tidy up swap entry splitting
  mm/shmem, swap: tidy up THP swapin checks
  mm/shmem, swap: avoid redundant Xarray lookup during swapin
  x86/ftrace: enable EXECMEM_ROX_CACHE for ftrace allocations
  x86/kprobes: enable EXECMEM_ROX_CACHE for kprobes allocations
  execmem: drop writable parameter from execmem_fill_trapping_insns()
  execmem: add fallback for failures in vmalloc(VM_ALLOW_HUGE_VMAP)
  execmem: move execmem_force_rw() and execmem_restore_rox() before use
  execmem: rework execmem_cache_free()
  execmem: introduce execmem_alloc_rw()
  execmem: drop unused execmem_update_copy()
  mm: fix a UAF when vma->mm is freed after vma->vm_refcnt got dropped
  mm/rmap: add anon_vma lifetime debug check
  mm: remove mm/io-mapping.c
  ...
2025-08-05 16:02:07 +03:00
Linus Torvalds
e991acf1bc Significant patch series in this pull request:
- The 2 patch series "squashfs: Remove page->mapping references" from
   Matthew Wilcox gets us closer to being able to remove page->mapping.
 
 - The 5 patch series "relayfs: misc changes" from Jason Xing does some
   maintenance and minor feature addition work in relayfs.
 
 - The 5 patch series "kdump: crashkernel reservation from CMA" from Jiri
   Bohac switches us from static preallocation of the kdump crashkernel's
   working memory over to dynamic allocation.  So the difficulty of
   a-priori estimation of the second kernel's needs is removed and the
   first kernel obtains extra memory.
 
 - The 5 patch series "generalize panic_print's dump function to be used
   by other kernel parts" from Feng Tang implements some consolidation and
   rationalizatio of the various ways in which a faiing kernel splats
   information at the operator.
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Merge tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:
 "Significant patch series in this pull request:

   - "squashfs: Remove page->mapping references" (Matthew Wilcox) gets
     us closer to being able to remove page->mapping

   - "relayfs: misc changes" (Jason Xing) does some maintenance and
     minor feature addition work in relayfs

   - "kdump: crashkernel reservation from CMA" (Jiri Bohac) switches
     us from static preallocation of the kdump crashkernel's working
     memory over to dynamic allocation. So the difficulty of a-priori
     estimation of the second kernel's needs is removed and the first
     kernel obtains extra memory

   - "generalize panic_print's dump function to be used by other
     kernel parts" (Feng Tang) implements some consolidation and
     rationalization of the various ways in which a failing kernel
     splats information at the operator

* tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (80 commits)
  tools/getdelays: add backward compatibility for taskstats version
  kho: add test for kexec handover
  delaytop: enhance error logging and add PSI feature description
  samples: Kconfig: fix spelling mistake "instancess" -> "instances"
  fat: fix too many log in fat_chain_add()
  scripts/spelling.txt: add notifer||notifier to spelling.txt
  xen/xenbus: fix typo "notifer"
  net: mvneta: fix typo "notifer"
  drm/xe: fix typo "notifer"
  cxl: mce: fix typo "notifer"
  KVM: x86: fix typo "notifer"
  MAINTAINERS: add maintainers for delaytop
  ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below()
  ucount: fix atomic_long_inc_below() argument type
  kexec: enable CMA based contiguous allocation
  stackdepot: make max number of pools boot-time configurable
  lib/xxhash: remove unused functions
  init/Kconfig: restore CONFIG_BROKEN help text
  lib/raid6: update recov_rvv.c zero page usage
  docs: update docs after introducing delaytop
  ...
2025-08-03 16:23:09 -07:00
Xuanye Liu
881388f343 mm: add process info to bad rss-counter warning
Enhance the debugging information in check_mm() by including the process
name and PID when reporting bad rss-counter states.  This helps identify
which process is associated with the memory accounting issue.

Link: https://lkml.kernel.org/r/20250723100901.1909683-1-liuqiye2025@163.com
Signed-off-by: Xuanye Liu <liuqiye2025@163.com>
Acked-by: SeongJae Park <sj@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-08-02 12:06:08 -07:00
Thomas Gleixner
e703b7e247 futex: Move futex cleanup to __mmdrop()
Futex hash allocations are done in mm_init() and the cleanup happens in
__mmput(). That works most of the time, but there are mm instances which
are instantiated via mm_alloc() and freed via mmdrop(), which causes the
futex hash to be leaked.

Move the cleanup to __mmdrop().

Fixes: 56180dd20c ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t")
Reported-by: André Draszik <andre.draszik@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/all/87ldo5ihu0.ffs@tglx
Closes: https://lore.kernel.org/all/0c8cc83bb73abf080faf584f319008b67d0931db.camel@linaro.org
2025-08-02 15:11:52 +02:00
Linus Torvalds
c6439bfaab Deferred unwind changes for 6.17
This is the core infrastructure for the deferred unwinder that is required
 for sframes[1]. Several other patch series is based on this work although
 those patch series are not dependent on each other. In order to simplify the
 development, having this core series upstream will allow the other series to
 be worked on in parallel. The other series are:
 
 - The two patches to implement x86:
   https://lore.kernel.org/linux-trace-kernel/20250717004958.260781923@kernel.org/
   https://lore.kernel.org/linux-trace-kernel/20250717004958.432327787@kernel.org/
 
 - The s390 work:
   https://lore.kernel.org/linux-trace-kernel/20250710163522.3195293-1-jremus@linux.ibm.com/
 
 - The perf work:
   https://lore.kernel.org/linux-trace-kernel/20250718164119.089692174@kernel.org/
 
 - The ftrace work:
   https://lore.kernel.org/linux-trace-kernel/20250424192612.505622711@goodmis.org/
 
 - The sframe work:
   https://lore.kernel.org/linux-trace-kernel/20250717012848.927473176@kernel.org/
 
 And more is on the way.
 
 The core infrastructure adds the following in kernel APIs:
 
 - int unwind_user_faultable(struct unwind_stacktrace *trace);
 
     Performs a user space stack trace that may fault user pages in.
 
 - int unwind_deferred_init(struct unwind_work *work, unwind_callback_t func);
 
     Allows a tracer to register with the unwind deferred infrastructure.
 
 - int unwind_deferred_request(struct unwind_work *work, u64 *cookie);
 
     Used when a tracer request a deferred trace. Can be called from interrupt
     or NMI context.
 
 - void unwind_deferred_cancel(struct unwind_work *work);
 
     Called by a tracer to unregister from the deferred unwind infrastructure.
 
 - void unwind_deferred_task_exit(struct task_struct *task);
 
     Called by task exit code to flush any pending unwind requests.
 
 - void unwind_task_init(struct task_struct *task);
 
     Called by do_fork() to initialize the task struct for the deferred
     unwinder.
 
 - void unwind_task_free(struct task_struct *task);
 
     Called by do_exit() to free up any resources used by the deferred
     unwinder.
 
 None of the above is actually compiled unless an architecture enables it,
 which none currently do.
 
 [1] https://sourceware.org/binutils/wiki/sframe
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Merge tag 'trace-deferred-unwind-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull initial deferred unwind infrastructure from Steven Rostedt:
 "This is the core infrastructure for the deferred unwinder that is
  required for sframes[1]. Several other patch series are based on this
  work although those patch series are not dependent on each other. In
  order to simplify the development, having this core series upstream
  will allow the other series to be worked on in parallel. The other
  series are:

    - The two patches to implement x86 support [2] [3]

    - The s390 work [4]

    - The perf work [5]

    - The ftrace work [6]

    - The sframe work [7]

  And more is on the way.

  The core infrastructure adds the following in kernel APIs:

    - int unwind_user_faultable(struct unwind_stacktrace *trace);

        Performs a user space stack trace that may fault user pages in.

    - int unwind_deferred_init(struct unwind_work *work, unwind_callback_t func);

        Allows a tracer to register with the unwind deferred
        infrastructure.

    - int unwind_deferred_request(struct unwind_work *work, u64 *cookie);

        Used when a tracer request a deferred trace. Can be called from
        interrupt or NMI context.

    - void unwind_deferred_cancel(struct unwind_work *work);

        Called by a tracer to unregister from the deferred unwind
        infrastructure.

    - void unwind_deferred_task_exit(struct task_struct *task);

        Called by task exit code to flush any pending unwind requests.

    - void unwind_task_init(struct task_struct *task);

        Called by do_fork() to initialize the task struct for the
        deferred unwinder.

    - void unwind_task_free(struct task_struct *task);

        Called by do_exit() to free up any resources used by the
        deferred unwinder.

    None of the above is actually compiled unless an architecture enables it,
    which none currently do"

Link: https://sourceware.org/binutils/wiki/sframe [1]
Link: https://lore.kernel.org/linux-trace-kernel/20250717004958.260781923@kernel.org/ [2]
Link: https://lore.kernel.org/linux-trace-kernel/20250717004958.432327787@kernel.org/ [3]
Link: https://lore.kernel.org/linux-trace-kernel/20250710163522.3195293-1-jremus@linux.ibm.com/ [4]
Link: https://lore.kernel.org/linux-trace-kernel/20250718164119.089692174@kernel.org/ [5]
Link: https://lore.kernel.org/linux-trace-kernel/20250424192612.505622711@goodmis.org/ [6]
Link: https://lore.kernel.org/linux-trace-kernel/20250717012848.927473176@kernel.org/ [7]

* tag 'trace-deferred-unwind-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  unwind: Finish up unwind when a task exits
  unwind deferred: Use SRCU unwind_deferred_task_work()
  unwind: Add USED bit to only have one conditional on way back to user space
  unwind deferred: Add unwind_completed mask to stop spurious callbacks
  unwind deferred: Use bitmask to determine which callbacks to call
  unwind_user/deferred: Make unwind deferral requests NMI-safe
  unwind_user/deferred: Add deferred unwinding interface
  unwind_user/deferred: Add unwind cache
  unwind_user/deferred: Add unwind_user_faultable()
  unwind_user: Add user space unwinding API with frame pointer support
2025-08-01 09:46:24 -07:00
Linus Torvalds
4ff261e725 Runtime verification changes for 6.17
- Added Linear temporal logic monitors for RT application
 
   Real-time applications may have design flaws causing them to have
   unexpected latency. For example, the applications may raise page faults, or
   may be blocked trying to take a mutex without priority inheritance.
 
   However, while attempting to implement DA monitors for these real-time
   rules, deterministic automaton is found to be inappropriate as the
   specification language. The automaton is complicated, hard to understand,
   and error-prone.
 
   For these cases, linear temporal logic is found to be more suitable. The
   LTL is more concise and intuitive.
 
 - Make printk_deferred() public
 
   The new monitors needed access to printk_deferred(). Make them visible for
   the entire kernel.
 
 - Add a vpanic() to allow for va_list to be passed to panic.
 
 - Add rtapp container monitor.
 
   A collection of monitors that check for common problems with real-time
   applications that cause unexpected latency.
 
 - Add page fault tracepoints to risc-v
 
   These tracepoints are necessary to for the RV monitor to run on risc-v.
 
 - Fix the behaviour of the rv tool with -s and idle tasks.
 
 - Allow the rv tool to gracefully terminate with SIGTERM
 
 - Adjusts dot2c not to create lines over 100 columns
 
 - Properly order nested monitors in the RV Kconfig file
 
 - Return the registration error in all DA monitor instead of 0
 
 - Update and add new sched collection monitors
 
   Replace tss and sncid monitors with more complete sts:
   Not only prove that switches occur in scheduling context and scheduling
   needs interrupt disabled but also that each call to the scheduler
   disables interrupts to (optionally) switch.
 
   New monitor: nrp
    Preemption requires need resched which is cleared by any switch
    (includes a non optimal workaround for /nested/ preemptions)
 
   New monitor: sssw
    suspension requires setting the task to sleepable and, after the
    switch occurs, the task requires a wakeup to come back to runnable
 
   New monitor: opid
    waking and need-resched operations occur with interrupts and
    preemption disabled or in IRQ without explicitly disabling preemption
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Merge tag 'trace-rv-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull runtime verification updates from Steven Rostedt:

 - Added Linear temporal logic monitors for RT application

   Real-time applications may have design flaws causing them to have
   unexpected latency. For example, the applications may raise page
   faults, or may be blocked trying to take a mutex without priority
   inheritance.

   However, while attempting to implement DA monitors for these
   real-time rules, deterministic automaton is found to be inappropriate
   as the specification language. The automaton is complicated, hard to
   understand, and error-prone.

   For these cases, linear temporal logic is found to be more suitable.
   The LTL is more concise and intuitive.

 - Make printk_deferred() public

   The new monitors needed access to printk_deferred(). Make them
   visible for the entire kernel.

 - Add a vpanic() to allow for va_list to be passed to panic.

 - Add rtapp container monitor.

   A collection of monitors that check for common problems with
   real-time applications that cause unexpected latency.

 - Add page fault tracepoints to risc-v

   These tracepoints are necessary to for the RV monitor to run on
   risc-v.

 - Fix the behaviour of the rv tool with -s and idle tasks.

 - Allow the rv tool to gracefully terminate with SIGTERM

 - Adjusts dot2c not to create lines over 100 columns

 - Properly order nested monitors in the RV Kconfig file

 - Return the registration error in all DA monitor instead of 0

 - Update and add new sched collection monitors

   Replace tss and sncid monitors with more complete sts:

   Not only prove that switches occur in scheduling context and scheduling
   needs interrupt disabled but also that each call to the scheduler
   disables interrupts to (optionally) switch.

   New monitor: nrp
     Preemption requires need resched which is cleared by any switch
     (includes a non optimal workaround for /nested/ preemptions)

   New monitor: sssw
     suspension requires setting the task to sleepable and, after the
     switch occurs, the task requires a wakeup to come back to runnable

   New monitor: opid
      waking and need-resched operations occur with interrupts and
      preemption disabled or in IRQ without explicitly disabling
      preemption"

* tag 'trace-rv-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (48 commits)
  rv: Add opid per-cpu monitor
  rv: Add nrp and sssw per-task monitors
  rv: Replace tss and sncid monitors with more complete sts
  sched: Adapt sched tracepoints for RV task model
  rv: Retry when da monitor detects race conditions
  rv: Adjust monitor dependencies
  rv: Use strings in da monitors tracepoints
  rv: Remove trailing whitespace from tracepoint string
  rv: Add da_handle_start_run_event_ to per-task monitors
  rv: Fix wrong type cast in reactors_show() and monitor_reactor_show()
  rv: Fix wrong type cast in monitors_show()
  rv: Remove struct rv_monitor::reacting
  rv: Remove rv_reactor's reference counter
  rv: Merge struct rv_reactor_def into struct rv_reactor
  rv: Merge struct rv_monitor_def into struct rv_monitor
  rv: Remove unused field in struct rv_monitor_def
  rv: Return init error when registering monitors
  verification/rvgen: Organise Kconfig entries for nested monitors
  tools/dot2c: Fix generated files going over 100 column limit
  tools/rv: Stop gracefully also on SIGTERM
  ...
2025-07-30 16:23:12 -07:00
Linus Torvalds
4b290aae78 Summary
* Move sysctls out of the kern_table array
 
   This is the final move of ctl_tables into their respective subsystems. Only 5
   (out of the original 50) will remain in kernel/sysctl.c file; these handle
   either sysctl or common arch variables.
 
   By decentralizing sysctl registrations, subsystem maintainers regain control
   over their sysctl interfaces, improving maintainability and reducing the
   likelihood of merge conflicts.
 
 * docs: Remove false positives from check-sysctl-docs
 
   Stopped falsely identifying sysctls as undocumented or unimplemented in the
   check-sysctl-docs script. This script can now be used to automatically
   identify if documentation is missing.
 
 * Testing
 
   All these have been in linux-next since rc3, giving them a solid 3 to 4 weeks
   worth of testing. Additionally, sysctl selftests and kunit were also run
   locally on my x86_64
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Merge tag 'sysctl-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

Pull sysctl updates from Joel Granados:

 - Move sysctls out of the kern_table array

   This is the final move of ctl_tables into their respective
   subsystems. Only 5 (out of the original 50) will remain in
   kernel/sysctl.c file; these handle either sysctl or common arch
   variables.

   By decentralizing sysctl registrations, subsystem maintainers regain
   control over their sysctl interfaces, improving maintainability and
   reducing the likelihood of merge conflicts.

 - docs: Remove false positives from check-sysctl-docs

   Stopped falsely identifying sysctls as undocumented or unimplemented
   in the check-sysctl-docs script. This script can now be used to
   automatically identify if documentation is missing.

* tag 'sysctl-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl: (23 commits)
  docs: Downgrade arm64 & riscv from titles to comment
  docs: Replace spaces with tabs in check-sysctl-docs
  docs: Remove colon from ctltable title in vm.rst
  docs: Add awk section for ucount sysctl entries
  docs: Use skiplist when checking sysctl admin-guide
  docs: nixify check-sysctl-docs
  sysctl: rename kern_table -> sysctl_subsys_table
  kernel/sys.c: Move overflow{uid,gid} sysctl into kernel/sys.c
  uevent: mv uevent_helper into kobject_uevent.c
  sysctl: Removed unused variable
  sysctl: Nixify sysctl.sh
  sysctl: Remove superfluous includes from kernel/sysctl.c
  sysctl: Remove (very) old file changelog
  sysctl: Move sysctl_panic_on_stackoverflow to kernel/panic.c
  sysctl: move cad_pid into kernel/pid.c
  sysctl: Move tainted ctl_table into kernel/panic.c
  Input: sysrq: mv sysrq into drivers/tty/sysrq.c
  fork: mv threads-max into kernel/fork.c
  parisc/power: Move soft-power into power.c
  mm: move randomize_va_space into memory.c
  ...
2025-07-29 21:43:08 -07:00
Linus Torvalds
bf76f23aa1 Scheduler updates for v6.17:
Core scheduler changes:
 
  - Better tracking of maximum lag of tasks in presence of different
    slices duration, for better handling of lag in the fair
    scheduler. (Vincent Guittot)
 
  - Clean up and standardize #if/#else/#endif markers throughout
    the entire scheduler code base (Ingo Molnar)
 
  - Make SMP unconditional: build the SMP scheduler's
    data structures and logic on UP kernel too, even though
    they are not used, to simplify the scheduler and remove
    around 200 #ifdef/[#else]/#endif blocks from the
    scheduler. (Ingo Molnar)
 
  - Reorganize cgroup bandwidth control interface handling
    for better interfacing with sched_ext (Tejun Heo)
 
 Balancing:
 
  - Bump sd->max_newidle_lb_cost when newidle balance fails (Chris Mason)
  - Remove sched_domain_topology_level::flags to simplify the code (Prateek Nayak)
  - Simplify and clean up build_sched_topology() (Li Chen)
  - Optimize build_sched_topology() on large machines (Li Chen)
 
 Real-time scheduling:
 
  - Add initial version of proxy execution: a mechanism for mutex-owning
    tasks to inherit the scheduling context of higher priority waiters.
    Currently limited to a single runqueue and conditional on CONFIG_EXPERT,
    and other limitations. (John Stultz, Peter Zijlstra, Valentin Schneider)
 
  - Deadline scheduler (Juri Lelli):
 
    - Fix dl_servers initialization order (Juri Lelli)
    - Fix DL scheduler's root domain reinitialization logic (Juri Lelli)
    - Fix accounting bugs after global limits change (Juri Lelli)
    - Fix scalability regression by implementing less agressive dl_server handling
      (Peter Zijlstra)
 
 PSI:
 
  - Improve scalability by optimizing psi_group_change() cpu_clock() usage
    (Peter Zijlstra)
 
 Rust changes:
 
  - Make Task, CondVar and PollCondVar methods inline to avoid unnecessary
    function calls (Kunwu Chan, Panagiotis Foliadis)
 
  - Add might_sleep() support for Rust code: Rust's "#[track_caller]"
    mechanism is used so that Rust's might_sleep() doesn't need to be
    defined as a macro (Fujita Tomonori)
 
  - Introduce file_from_location() (Boqun Feng)
 
 Debugging & instrumentation:
 
  - Make clangd usable with scheduler source code files again (Peter Zijlstra)
 
  - tools: Add root_domains_dump.py which dumps root domains info (Juri Lelli)
 
  - tools: Add dl_bw_dump.py for printing bandwidth accounting info (Juri Lelli)
 
 Misc cleanups & fixes:
 
  - Remove play_idle() (Feng Lee)
 
  - Fix check_preemption_disabled() (Sebastian Andrzej Siewior)
 
  - Do not call __put_task_struct() on RT if pi_blocked_on is set
    (Luis Claudio R. Goncalves)
 
  - Correct the comment in place_entity() (wang wei)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
 "Core scheduler changes:

   - Better tracking of maximum lag of tasks in presence of different
     slices duration, for better handling of lag in the fair scheduler
     (Vincent Guittot)

   - Clean up and standardize #if/#else/#endif markers throughout the
     entire scheduler code base (Ingo Molnar)

   - Make SMP unconditional: build the SMP scheduler's data structures
     and logic on UP kernel too, even though they are not used, to
     simplify the scheduler and remove around 200 #ifdef/[#else]/#endif
     blocks from the scheduler (Ingo Molnar)

   - Reorganize cgroup bandwidth control interface handling for better
     interfacing with sched_ext (Tejun Heo)

  Balancing:

   - Bump sd->max_newidle_lb_cost when newidle balance fails (Chris
     Mason)

   - Remove sched_domain_topology_level::flags to simplify the code
     (Prateek Nayak)

   - Simplify and clean up build_sched_topology() (Li Chen)

   - Optimize build_sched_topology() on large machines (Li Chen)

  Real-time scheduling:

   - Add initial version of proxy execution: a mechanism for
     mutex-owning tasks to inherit the scheduling context of higher
     priority waiters.

     Currently limited to a single runqueue and conditional on
     CONFIG_EXPERT, and other limitations (John Stultz, Peter Zijlstra,
     Valentin Schneider)

   - Deadline scheduler (Juri Lelli):
      - Fix dl_servers initialization order (Juri Lelli)
      - Fix DL scheduler's root domain reinitialization logic (Juri
        Lelli)
      - Fix accounting bugs after global limits change (Juri Lelli)
      - Fix scalability regression by implementing less agressive
        dl_server handling (Peter Zijlstra)

  PSI:

   - Improve scalability by optimizing psi_group_change() cpu_clock()
     usage (Peter Zijlstra)

  Rust changes:

   - Make Task, CondVar and PollCondVar methods inline to avoid
     unnecessary function calls (Kunwu Chan, Panagiotis Foliadis)

   - Add might_sleep() support for Rust code: Rust's "#[track_caller]"
     mechanism is used so that Rust's might_sleep() doesn't need to be
     defined as a macro (Fujita Tomonori)

   - Introduce file_from_location() (Boqun Feng)

  Debugging & instrumentation:

   - Make clangd usable with scheduler source code files again (Peter
     Zijlstra)

   - tools: Add root_domains_dump.py which dumps root domains info (Juri
     Lelli)

   - tools: Add dl_bw_dump.py for printing bandwidth accounting info
     (Juri Lelli)

  Misc cleanups & fixes:

   - Remove play_idle() (Feng Lee)

   - Fix check_preemption_disabled() (Sebastian Andrzej Siewior)

   - Do not call __put_task_struct() on RT if pi_blocked_on is set (Luis
     Claudio R. Goncalves)

   - Correct the comment in place_entity() (wang wei)"

* tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (84 commits)
  sched/idle: Remove play_idle()
  sched: Do not call __put_task_struct() on rt if pi_blocked_on is set
  sched: Start blocked_on chain processing in find_proxy_task()
  sched: Fix proxy/current (push,pull)ability
  sched: Add an initial sketch of the find_proxy_task() function
  sched: Fix runtime accounting w/ split exec & sched contexts
  sched: Move update_curr_task logic into update_curr_se
  locking/mutex: Add p->blocked_on wrappers for correctness checks
  locking/mutex: Rework task_struct::blocked_on
  sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable
  sched/topology: Remove sched_domain_topology_level::flags
  x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled
  x86/smpboot: moves x86_topology to static initialize and truncate
  x86/smpboot: remove redundant CONFIG_SCHED_SMT
  smpboot: introduce SDTL_INIT() helper to tidy sched topology setup
  tools/sched: Add dl_bw_dump.py for printing bandwidth accounting info
  tools/sched: Add root_domains_dump.py which dumps root domains info
  sched/deadline: Fix accounting after global limits change
  sched/deadline: Reset extra_bw to max_bw when clearing root domains
  sched/deadline: Initialize dl_servers after SMP
  ...
2025-07-29 17:42:52 -07:00
Linus Torvalds
f38b1f243e Update for the futex subsystem:
- Switch the reference counting to a RCU based per-CPU reference to
      address a performance bottleneck vs. the single instance rcuref
      variant.
 
    - Make the futex selftest build on 32-bit architectures which only
      support 64-bit time_t, e.g. RISCV-32.
 
    - Cleanups and improvements in selftests and futex bench
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Merge tag 'locking-futex-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull futex updates from Thomas Gleixner:

 - Switch the reference counting to a RCU based per-CPU reference to
   address a performance bottleneck vs the single instance rcuref
   variant

 - Make the futex selftest build on 32-bit architectures which only
   support 64-bit time_t, e.g. RISCV-32

 - Cleanups and improvements in selftests and futex bench

* tag 'locking-futex-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests/futex: Fix spelling mistake "Succeffuly" -> "Successfully"
  selftests/futex: Define SYS_futex on 32-bit architectures with 64-bit time_t
  perf bench futex: Remove support for IMMUTABLE
  selftests/futex: Remove support for IMMUTABLE
  futex: Remove support for IMMUTABLE
  futex: Make futex_private_hash_get() static
  futex: Use RCU-based per-CPU reference counting instead of rcuref_t
  selftests/futex: Adapt the private hash test to RCU related changes
2025-07-29 14:39:42 -07:00
Steven Rostedt
5e32d0f15c unwind_user/deferred: Add unwind_user_faultable()
Add a new API to retrieve a user space callstack called
unwind_user_faultable(). The difference between this user space stack
tracer from the current user space stack tracer is that this must be
called from faultable context as it may use routines to access user space
data that needs to be faulted in.

It can be safely called from entering or exiting a system call as the code
can still be faulted in there.

This code is based on work by Josh Poimboeuf's deferred unwinding code:

Link: https://lore.kernel.org/all/6052e8487746603bdb29b65f4033e739092d9925.1737511963.git.jpoimboe@kernel.org/

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Indu Bhagat <indu.bhagat@oracle.com>
Cc: "Jose E. Marchesi" <jemarch@gnu.org>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Sam James <sam@gentoo.org>
Link: https://lore.kernel.org/20250729182405.147896868@kernel.org
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-07-29 14:46:07 -04:00
Linus Torvalds
8e736a2eea hardening updates for v6.17-rc1
- Introduce and start using TRAILING_OVERLAP() helper for fixing
   embedded flex array instances (Gustavo A. R. Silva)
 
 - mux: Convert mux_control_ops to a flex array member in mux_chip
   (Thorsten Blum)
 
 - string: Group str_has_prefix() and strstarts() (Andy Shevchenko)
 
 - Remove KCOV instrumentation from __init and __head (Ritesh Harjani,
   Kees Cook)
 
 - Refactor and rename stackleak feature to support Clang
 
 - Add KUnit test for seq_buf API
 
 - Fix KUnit fortify test under LTO
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Merge tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - Introduce and start using TRAILING_OVERLAP() helper for fixing
   embedded flex array instances (Gustavo A. R. Silva)

 - mux: Convert mux_control_ops to a flex array member in mux_chip
   (Thorsten Blum)

 - string: Group str_has_prefix() and strstarts() (Andy Shevchenko)

 - Remove KCOV instrumentation from __init and __head (Ritesh Harjani,
   Kees Cook)

 - Refactor and rename stackleak feature to support Clang

 - Add KUnit test for seq_buf API

 - Fix KUnit fortify test under LTO

* tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (22 commits)
  sched/task_stack: Add missing const qualifier to end_of_stack()
  kstack_erase: Support Clang stack depth tracking
  kstack_erase: Add -mgeneral-regs-only to silence Clang warnings
  init.h: Disable sanitizer coverage for __init and __head
  kstack_erase: Disable kstack_erase for all of arm compressed boot code
  x86: Handle KCOV __init vs inline mismatches
  arm64: Handle KCOV __init vs inline mismatches
  s390: Handle KCOV __init vs inline mismatches
  arm: Handle KCOV __init vs inline mismatches
  mips: Handle KCOV __init vs inline mismatch
  powerpc/mm/book3s64: Move kfence and debug_pagealloc related calls to __init section
  configs/hardening: Enable CONFIG_INIT_ON_FREE_DEFAULT_ON
  configs/hardening: Enable CONFIG_KSTACK_ERASE
  stackleak: Split KSTACK_ERASE_CFLAGS from GCC_PLUGINS_CFLAGS
  stackleak: Rename stackleak_track_stack to __sanitizer_cov_stack_depth
  stackleak: Rename STACKLEAK to KSTACK_ERASE
  seq_buf: Introduce KUnit tests
  string: Group str_has_prefix() and strstarts()
  kunit/fortify: Add back "volatile" for sizeof() constants
  acpi: nfit: intel: avoid multiple -Wflex-array-member-not-at-end warnings
  ...
2025-07-28 17:16:12 -07:00
Linus Torvalds
d900c4ce63 execve updates for v6.17
- Introduce regular REGSET note macros arch-wide (Dave Martin)
 
 - Remove arbitrary 4K limitation of program header size (Yin Fengwei)
 
 - Reorder function qualifiers for copy_clone_args_from_user() (Dishank Jogi)
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Merge tag 'execve-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Introduce regular REGSET note macros arch-wide (Dave Martin)

 - Remove arbitrary 4K limitation of program header size (Yin Fengwei)

 - Reorder function qualifiers for copy_clone_args_from_user() (Dishank Jogi)

* tag 'execve-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (25 commits)
  fork: reorder function qualifiers for copy_clone_args_from_user
  binfmt_elf: remove the 4k limitation of program header size
  binfmt_elf: Warn on missing or suspicious regset note names
  xtensa: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  um: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  x86/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  sparc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  sh: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  s390/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  riscv: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  powerpc/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  parisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  openrisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  nios2: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  MIPS: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  m68k: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  LoongArch: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  hexagon: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  csky: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  arm64: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  ...
2025-07-28 17:11:40 -07:00
Joel Granados
8e5f04b0d5 fork: mv threads-max into kernel/fork.c
make sysctl_max_threads static as it no longer needs to be exported into
sysctl.c.

This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kernel/sysctl.c.

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
2025-07-23 11:52:48 +02:00
Kees Cook
57fbad15c2 stackleak: Rename STACKLEAK to KSTACK_ERASE
In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:

- Add the new top-level CONFIG_KSTACK_ERASE option which will be
  implemented either with the stackleak GCC plugin, or with the Clang
  stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
  but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
  for what it does rather than what it protects against), but leave as
  many of the internals alone as possible to avoid even more churn.

While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-21 21:35:01 -07:00
Dishank Jogi
7f71195c15 fork: reorder function qualifiers for copy_clone_args_from_user
Change the order of function qualifiers from 'noinline static' to 'static noinline'
in copy_clone_args_from_user for consistency with kernel coding style.

No functional change intended. The goal is to improve readability and
maintain consistent ordering of qualifiers across the codebase.

Signed-off-by: Dishank Jogi <dishank.jogi@siqol.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250716093525.449994-1-dishank.jogi@siqol.com
Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-17 16:37:05 -07:00
Peter Zijlstra
44e4e0297c locking/mutex: Rework task_struct::blocked_on
Track the blocked-on relation for mutexes, to allow following this
relation at schedule time.

   task
     | blocked-on
     v
   mutex
     | owner
     v
   task

This all will be used for tracking blocked-task/mutex chains
with the prox-execution patch in a similar fashion to how
priority inheritance is done with rt_mutexes.

For serialization, blocked-on is only set by the task itself
(current). And both when setting or clearing (potentially by
others), is done while holding the mutex::wait_lock.

[minor changes while rebasing]
[jstultz: Fix blocked_on tracking in __mutex_lock_common in error paths]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20250712033407.2383110-3-jstultz@google.com
2025-07-14 17:16:31 +02:00
Peter Zijlstra
56180dd20c futex: Use RCU-based per-CPU reference counting instead of rcuref_t
The use of rcuref_t for reference counting introduces a performance bottleneck
when accessed concurrently by multiple threads during futex operations.

Replace rcuref_t with special crafted per-CPU reference counters. The
lifetime logic remains the same.

The newly allocate private hash starts in FR_PERCPU state. In this state, each
futex operation that requires the private hash uses a per-CPU counter (an
unsigned int) for incrementing or decrementing the reference count.

When the private hash is about to be replaced, the per-CPU counters are
migrated to a atomic_t counter mm_struct::futex_atomic.
The migration process:
- Waiting for one RCU grace period to ensure all users observe the
  current private hash. This can be skipped if a grace period elapsed
  since the private hash was assigned.

- futex_private_hash::state is set to FR_ATOMIC, forcing all users to
  use mm_struct::futex_atomic for reference counting.

- After a RCU grace period, all users are guaranteed to be using the
  atomic counter. The per-CPU counters can now be summed up and added to
  the atomic_t counter. If the resulting count is zero, the hash can be
  safely replaced. Otherwise, active users still hold a valid reference.

- Once the atomic reference count drops to zero, the next futex
  operation will switch to the new private hash.

call_rcu_hurry() is used to speed up transition which otherwise might be
delay with RCU_LAZY. There is nothing wrong with using call_rcu(). The
side effects would be that on auto scaling the new hash is used later
and the SET_SLOTS prctl() will block longer.

[bigeasy: commit description + mm get/ put_async]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-3-bigeasy@linutronix.de
2025-07-11 16:02:00 +02:00
Pasha Tatashin
64960497ea fork: clean up ifdef logic around stack allocation
There is an unneeded OR in the ifdef functions that are used to allocate
and free kernel stacks based on direct map or vmap.  Adding dynamic stack
support would complicate this logic even further.

Therefore, clean up by changing the order so OR is no longer needed.

Link: https://lkml.kernel.org/r/20250618-fork-fixes-v4-1-2e05a2e1f5fc@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/20240311164638.2015063-3-pasha.tatashin@soleen.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-09 22:57:54 -07:00
Linus Walleij
f7b0ff2bc9 fork: define a local GFP_VMAP_STACK
The current allocation of VMAP stack memory is using (THREADINFO_GFP &
~__GFP_ACCOUNT) which is a complicated way of saying (GFP_KERNEL |
__GFP_ZERO):

<linux/thread_info.h>:
define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO)
<linux/gfp_types.h>:
define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)

This is an unfortunate side-effect of independent changes blurring the
picture:

commit 19809c2da2 changed (THREADINFO_GFP |
__GFP_HIGHMEM) to just THREADINFO_GFP since highmem became implicit.

commit 9b6f7e163c then added stack caching
and rewrote the allocation to (THREADINFO_GFP & ~__GFP_ACCOUNT) as cached
stacks need to be accounted separately.  However that code, when it
eventually accounts the memory does this:

  ret = memcg_kmem_charge(vm->pages[i], GFP_KERNEL, 0)

so the memory is charged as a GFP_KERNEL allocation.

Define a unique GFP_VMAP_STACK to use
GFP_KERNEL | __GFP_ZERO and move the comment there.

Link: https://lkml.kernel.org/r/20250509-gfp-stack-v1-1-82f6f7efc210@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reported-by: Mateusz Guzik <mjguzik@gmail.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-09 22:57:50 -07:00
Pasha Tatashin
449e0b4ed5 fork: clean-up naming of vm_stack/vm_struct variables in vmap stacks code
There are two data types: "struct vm_struct" and "struct vm_stack" that
have the same local variable names: vm_stack, or vm, or s, which makes the
code confusing to read.

Change the code so the naming is consistent:

struct vm_struct is always called vm_area
struct vm_stack is always called vm_stack

One change altering vfree(vm_stack) to vfree(vm_area->addr) may look like
a semantic change but it is not: vm_area->addr points to the vm_stack. 
This was done to improve readability.

[linus.walleij@linaro.org: rebased and added new users of the variable names, address review comments]
Link: https://lore.kernel.org/20240311164638.2015063-4-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20250509-fork-fixes-v3-2-e6c69dd356f2@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-09 22:57:50 -07:00
Nam Cao
a9769a5b98 rv: Add support for LTL monitors
While attempting to implement DA monitors for some complex specifications,
deterministic automaton is found to be inappropriate as the specification
language. The automaton is complicated, hard to understand, and
error-prone.

For these cases, linear temporal logic is more suitable as the
specification language.

Add support for linear temporal logic runtime verification monitor.

Cc: John Ogness <john.ogness@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/d366c1fed60ed4e8f6451f3c15a99755f2740b5f.1752088709.git.namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-07-09 15:27:01 -04:00
Al Viro
a683a5b2ba
fold fs_struct->{lock,seq} into a seqlock
The combination of spinlock_t lock and seqcount_spinlock_t seq
in struct fs_struct is an open-coded seqlock_t (see linux/seqlock_types.h).
	Combine and switch to equivalent seqlock_t primitives.  AFAICS,
that does end up with the same sequence of underlying operations in all
cases.
	While we are at it, get_fs_pwd() is open-coded verbatim in
get_path_from_fd(); rather than applying conversion to it, replace with
the call of get_fs_pwd() there.  Not worth splitting the commit for that,
IMO...

	A bit of historical background - conversion of seqlock_t to
use of seqcount_spinlock_t happened several months after the same
had been done to struct fs_struct; switching fs_struct to seqlock_t
could've been done immediately after that, but it looks like nobody
had gotten around to that until now.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/20250702053437.GC1880847@ZenIV
Acked-by: Ahmed S. Darwish <darwi@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-07-08 10:25:19 +02:00
Linus Torvalds
00c010e130 - The 11 patch series "Add folio_mk_pte()" from Matthew Wilcox
simplifies the act of creating a pte which addresses the first page in a
   folio and reduces the amount of plumbing which architecture must
   implement to provide this.
 
 - The 8 patch series "Misc folio patches for 6.16" from Matthew Wilcox
   is a shower of largely unrelated folio infrastructure changes which
   clean things up and better prepare us for future work.
 
 - The 3 patch series "memory,x86,acpi: hotplug memory alignment
   advisement" from Gregory Price adds early-init code to prevent x86 from
   leaving physical memory unused when physical address regions are not
   aligned to memory block size.
 
 - The 2 patch series "mm/compaction: allow more aggressive proactive
   compaction" from Michal Clapinski provides some tuning of the (sadly,
   hard-coded (more sadly, not auto-tuned)) thresholds for our invokation
   of proactive compaction.  In a simple test case, the reduction of a guest
   VM's memory consumption was dramatic.
 
 - The 8 patch series "Minor cleanups and improvements to swap freeing
   code" from Kemeng Shi provides some code cleaups and a small efficiency
   improvement to this part of our swap handling code.
 
 - The 6 patch series "ptrace: introduce PTRACE_SET_SYSCALL_INFO API"
   from Dmitry Levin adds the ability for a ptracer to modify syscalls
   arguments.  At this time we can alter only "system call information that
   are used by strace system call tampering, namely, syscall number,
   syscall arguments, and syscall return value.
 
   This series should have been incorporated into mm.git's "non-MM"
   branch, but I goofed.
 
 - The 3 patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report
   guard regions" from Andrei Vagin extends the info returned by the
   PAGEMAP_SCAN ioctl against /proc/pid/pagemap.  This permits CRIU to more
   efficiently get at the info about guard regions.
 
 - The 2 patch series "Fix parameter passed to page_mapcount_is_type()"
   from Gavin Shan implements that fix.  No runtime effect is expected
   because validate_page_before_insert() happens to fix up this error.
 
 - The 3 patch series "kernel/events/uprobes: uprobe_write_opcode()
   rewrite" from David Hildenbrand basically brings uprobe text poking into
   the current decade.  Remove a bunch of hand-rolled implementation in
   favor of using more current facilities.
 
 - The 3 patch series "mm/ptdump: Drop assumption that pxd_val() is u64"
   from Anshuman Khandual provides enhancements and generalizations to the
   pte dumping code.  This might be needed when 128-bit Page Table
   Descriptors are enabled for ARM.
 
 - The 12 patch series "Always call constructor for kernel page tables"
   from Kevin Brodsky "ensures that the ctor/dtor is always called for
   kernel pgtables, as it already is for user pgtables".  This permits the
   addition of more functionality such as "insert hooks to protect page
   tables".  This change does result in various architectures performing
   unnecesary work, but this is fixed up where it is anticipated to occur.
 
 - The 9 patch series "Rust support for mm_struct, vm_area_struct, and
   mmap" from Alice Ryhl adds plumbing to permit Rust access to core MM
   structures.
 
 - The 3 patch series "fix incorrectly disallowed anonymous VMA merges"
   from Lorenzo Stoakes takes advantage of some VMA merging opportunities
   which we've been missing for 15 years.
 
 - The 4 patch series "mm/madvise: batch tlb flushes for MADV_DONTNEED
   and MADV_FREE" from SeongJae Park optimizes process_madvise()'s TLB
   flushing.  Instead of flushing each address range in the provided iovec,
   we batch the flushing across all the iovec entries.  The syscall's cost
   was approximately halved with a microbenchmark which was designed to
   load this particular operation.
 
 - The 6 patch series "Track node vacancy to reduce worst case allocation
   counts" from Sidhartha Kumar makes the maple tree smarter about its node
   preallocation.  stress-ng mmap performance increased by single-digit
   percentages and the amount of unnecessarily preallocated memory was
   dramaticelly reduced.
 
 - The 3 patch series "mm/gup: Minor fix, cleanup and improvements" from
   Baoquan He removes a few unnecessary things which Baoquan noted when
   reading the code.
 
 - The 3 patch series ""Enhance sysfs handling for memory hotplug in
   weighted interleave" from Rakie Kim "enhances the weighted interleave
   policy in the memory management subsystem by improving sysfs handling,
   fixing memory leaks, and introducing dynamic sysfs updates for memory
   hotplug support".  Fixes things on error paths which we are unlikely to
   hit.
 
 - The 7 patch series "mm/damon: auto-tune DAMOS for NUMA setups
   including tiered memory" from SeongJae Park introduces new DAMOS quota
   goal metrics which eliminate the manual tuning which is required when
   utilizing DAMON for memory tiering.
 
 - The 5 patch series "mm/vmalloc.c: code cleanup and improvements" from
   Baoquan He provides cleanups and small efficiency improvements which
   Baoquan found via code inspection.
 
 - The 2 patch series "vmscan: enforce mems_effective during demotion"
   from Gregory Price "changes reclaim to respect cpuset.mems_effective
   during demotion when possible".  because "presently, reclaim explicitly
   ignores cpuset.mems_effective when demoting, which may cause the cpuset
   settings to violated." "This is useful for isolating workloads on a
   multi-tenant system from certain classes of memory more consistently."
 
 - The 2 patch series ""Clean up split_huge_pmd_locked() and remove
   unnecessary folio pointers" from Gavin Guo provides minor cleanups and
   efficiency gains in in the huge page splitting and migrating code.
 
 - The 3 patch series "Use kmem_cache for memcg alloc" from Huan Yang
   creates a slab cache for `struct mem_cgroup', yielding improved memory
   utilization.
 
 - The 4 patch series "add max arg to swappiness in memory.reclaim and
   lru_gen" from Zhongkun He adds a new "max" argument to the "swappiness="
   argument for memory.reclaim MGLRU's lru_gen.  This directs proactive
   reclaim to reclaim from only anon folios rather than file-backed folios.
 
 - The 17 patch series "kexec: introduce Kexec HandOver (KHO)" from Mike
   Rapoport is the first step on the path to permitting the kernel to
   maintain existing VMs while replacing the host kernel via file-based
   kexec.  At this time only memblock's reserve_mem is preserved.
 
 - The 7 patch series "mm: Introduce for_each_valid_pfn()" from David
   Woodhouse provides and uses a smarter way of looping over a pfn range.
   By skipping ranges of invalid pfns.
 
 - The 2 patch series "sched/numa: Skip VMA scanning on memory pinned to
   one NUMA node via cpuset.mems" from Libo Chen removes a lot of pointless
   VMA scanning when a task is pinned a single NUMA mode.  Dramatic
   performance benefits were seen in some real world cases.
 
 - The 2 patch series "JFS: Implement migrate_folio for
   jfs_metapage_aops" from Shivank Garg addresses a warning which occurs
   during memory compaction when using JFS.
 
 - The 4 patch series "move all VMA allocation, freeing and duplication
   logic to mm" from Lorenzo Stoakes moves some VMA code from kernel/fork.c
   into the more appropriate mm/vma.c.
 
 - The 6 patch series "mm, swap: clean up swap cache mapping helper" from
   Kairui Song provides code consolidation and cleanups related to the
   folio_index() function.
 
 - The 2 patch series "mm/gup: Cleanup memfd_pin_folios()" from Vishal
   Moola does that.
 
 - The 8 patch series "memcg: Fix test_memcg_min/low test failures" from
   Waiman Long addresses some bogus failures which are being reported by
   the test_memcontrol selftest.
 
 - The 3 patch series "eliminate mmap() retry merge, add .mmap_prepare
   hook" from Lorenzo Stoakes commences the deprecation of
   file_operations.mmap() in favor of the new
   file_operations.mmap_prepare().  The latter is more restrictive and
   prevents drivers from messing with things in ways which, amongst other
   problems, may defeat VMA merging.
 
 - The 4 patch series "memcg: decouple memcg and objcg stocks"" from
   Shakeel Butt decouples the per-cpu memcg charge cache from the objcg's
   one.  This is a step along the way to making memcg and objcg charging
   NMI-safe, which is a BPF requirement.
 
 - The 6 patch series "mm/damon: minor fixups and improvements for code,
   tests, and documents" from SeongJae Park is "yet another batch of
   miscellaneous DAMON changes.  Fix and improve minor problems in code,
   tests and documents."
 
 - The 7 patch series "memcg: make memcg stats irq safe" from Shakeel
   Butt converts memcg stats to be irq safe.  Another step along the way to
   making memcg charging and stats updates NMI-safe, a BPF requirement.
 
 - The 4 patch series "Let unmap_hugepage_range() and several related
   functions take folio instead of page" from Fan Ni provides folio
   conversions in the hugetlb code.
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Merge tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
   creating a pte which addresses the first page in a folio and reduces
   the amount of plumbing which architecture must implement to provide
   this.

 - "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
   largely unrelated folio infrastructure changes which clean things up
   and better prepare us for future work.

 - "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
   Price adds early-init code to prevent x86 from leaving physical
   memory unused when physical address regions are not aligned to memory
   block size.

 - "mm/compaction: allow more aggressive proactive compaction" from
   Michal Clapinski provides some tuning of the (sadly, hard-coded (more
   sadly, not auto-tuned)) thresholds for our invokation of proactive
   compaction. In a simple test case, the reduction of a guest VM's
   memory consumption was dramatic.

 - "Minor cleanups and improvements to swap freeing code" from Kemeng
   Shi provides some code cleaups and a small efficiency improvement to
   this part of our swap handling code.

 - "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
   adds the ability for a ptracer to modify syscalls arguments. At this
   time we can alter only "system call information that are used by
   strace system call tampering, namely, syscall number, syscall
   arguments, and syscall return value.

   This series should have been incorporated into mm.git's "non-MM"
   branch, but I goofed.

 - "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
   Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
   against /proc/pid/pagemap. This permits CRIU to more efficiently get
   at the info about guard regions.

 - "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
   implements that fix. No runtime effect is expected because
   validate_page_before_insert() happens to fix up this error.

 - "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
   Hildenbrand basically brings uprobe text poking into the current
   decade. Remove a bunch of hand-rolled implementation in favor of
   using more current facilities.

 - "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
   Khandual provides enhancements and generalizations to the pte dumping
   code. This might be needed when 128-bit Page Table Descriptors are
   enabled for ARM.

 - "Always call constructor for kernel page tables" from Kevin Brodsky
   ensures that the ctor/dtor is always called for kernel pgtables, as
   it already is for user pgtables.

   This permits the addition of more functionality such as "insert hooks
   to protect page tables". This change does result in various
   architectures performing unnecesary work, but this is fixed up where
   it is anticipated to occur.

 - "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
   Ryhl adds plumbing to permit Rust access to core MM structures.

 - "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
   Stoakes takes advantage of some VMA merging opportunities which we've
   been missing for 15 years.

 - "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
   SeongJae Park optimizes process_madvise()'s TLB flushing.

   Instead of flushing each address range in the provided iovec, we
   batch the flushing across all the iovec entries. The syscall's cost
   was approximately halved with a microbenchmark which was designed to
   load this particular operation.

 - "Track node vacancy to reduce worst case allocation counts" from
   Sidhartha Kumar makes the maple tree smarter about its node
   preallocation.

   stress-ng mmap performance increased by single-digit percentages and
   the amount of unnecessarily preallocated memory was dramaticelly
   reduced.

 - "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
   a few unnecessary things which Baoquan noted when reading the code.

 - ""Enhance sysfs handling for memory hotplug in weighted interleave"
   from Rakie Kim "enhances the weighted interleave policy in the memory
   management subsystem by improving sysfs handling, fixing memory
   leaks, and introducing dynamic sysfs updates for memory hotplug
   support". Fixes things on error paths which we are unlikely to hit.

 - "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
   from SeongJae Park introduces new DAMOS quota goal metrics which
   eliminate the manual tuning which is required when utilizing DAMON
   for memory tiering.

 - "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
   provides cleanups and small efficiency improvements which Baoquan
   found via code inspection.

 - "vmscan: enforce mems_effective during demotion" from Gregory Price
   changes reclaim to respect cpuset.mems_effective during demotion when
   possible. because presently, reclaim explicitly ignores
   cpuset.mems_effective when demoting, which may cause the cpuset
   settings to violated.

   This is useful for isolating workloads on a multi-tenant system from
   certain classes of memory more consistently.

 - "Clean up split_huge_pmd_locked() and remove unnecessary folio
   pointers" from Gavin Guo provides minor cleanups and efficiency gains
   in in the huge page splitting and migrating code.

 - "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
   for `struct mem_cgroup', yielding improved memory utilization.

 - "add max arg to swappiness in memory.reclaim and lru_gen" from
   Zhongkun He adds a new "max" argument to the "swappiness=" argument
   for memory.reclaim MGLRU's lru_gen.

   This directs proactive reclaim to reclaim from only anon folios
   rather than file-backed folios.

 - "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
   first step on the path to permitting the kernel to maintain existing
   VMs while replacing the host kernel via file-based kexec. At this
   time only memblock's reserve_mem is preserved.

 - "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
   and uses a smarter way of looping over a pfn range. By skipping
   ranges of invalid pfns.

 - "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
   cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
   when a task is pinned a single NUMA mode.

   Dramatic performance benefits were seen in some real world cases.

 - "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
   Garg addresses a warning which occurs during memory compaction when
   using JFS.

 - "move all VMA allocation, freeing and duplication logic to mm" from
   Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
   appropriate mm/vma.c.

 - "mm, swap: clean up swap cache mapping helper" from Kairui Song
   provides code consolidation and cleanups related to the folio_index()
   function.

 - "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.

 - "memcg: Fix test_memcg_min/low test failures" from Waiman Long
   addresses some bogus failures which are being reported by the
   test_memcontrol selftest.

 - "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
   Stoakes commences the deprecation of file_operations.mmap() in favor
   of the new file_operations.mmap_prepare().

   The latter is more restrictive and prevents drivers from messing with
   things in ways which, amongst other problems, may defeat VMA merging.

 - "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
   the per-cpu memcg charge cache from the objcg's one.

   This is a step along the way to making memcg and objcg charging
   NMI-safe, which is a BPF requirement.

 - "mm/damon: minor fixups and improvements for code, tests, and
   documents" from SeongJae Park is yet another batch of miscellaneous
   DAMON changes. Fix and improve minor problems in code, tests and
   documents.

 - "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
   stats to be irq safe. Another step along the way to making memcg
   charging and stats updates NMI-safe, a BPF requirement.

 - "Let unmap_hugepage_range() and several related functions take folio
   instead of page" from Fan Ni provides folio conversions in the
   hugetlb code.

* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
  mm: pcp: increase pcp->free_count threshold to trigger free_high
  mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
  mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
  mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
  mm/hugetlb: pass folio instead of page to unmap_ref_private()
  memcg: objcg stock trylock without irq disabling
  memcg: no stock lock for cpu hot-unplug
  memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
  memcg: make count_memcg_events re-entrant safe against irqs
  memcg: make mod_memcg_state re-entrant safe against irqs
  memcg: move preempt disable to callers of memcg_rstat_updated
  memcg: memcg_rstat_updated re-entrant safe against irqs
  mm: khugepaged: decouple SHMEM and file folios' collapse
  selftests/eventfd: correct test name and improve messages
  alloc_tag: check mem_profiling_support in alloc_tag_init
  Docs/damon: update titles and brief introductions to explain DAMOS
  selftests/damon/_damon_sysfs: read tried regions directories in order
  mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
  mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
  mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
  ...
2025-05-31 15:44:16 -07:00
Linus Torvalds
b3570b00dc Locking changes for v6.16:
Futexes:
 
    - Add support for task local hash maps (Sebastian Andrzej Siewior,
      Peter Zijlstra)
 
    - Implement the FUTEX2_NUMA ABI, which feature extends the futex
      interface to be NUMA-aware. On NUMA-aware futexes a second u32
      word containing the NUMA node is added to after the u32 futex value
      word. (Peter Zijlstra)
 
    - Implement the FUTEX2_MPOL ABI, which feature extends the futex
      interface to be mempolicy-aware as well, to further refine futex
      node mappings and lookups. (Peter Zijlstra)
 
   Locking primitives:
 
    - Misc cleanups (Andy Shevchenko, Borislav Petkov, Colin Ian King,
                     Ingo Molnar, Nam Cao, Peter Zijlstra)
 
   Lockdep:
 
    - Prevent abuse of lockdep subclasses (Waiman Long)
    - Add number of dynamic keys to /proc/lockdep_stats (Waiman Long)
 
 Plus misc cleanups and fixes.
 
 Note that the tree includes the following dependent out-of-subsystem
 changes as well:
 
  - rcuref: Provide rcuref_is_dead()
  - mm: Add vmalloc_huge_node()
  - mm: Add the mmap_read_lock guard to <linux/mmap_lock.h>
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "Futexes:

   - Add support for task local hash maps (Sebastian Andrzej Siewior,
     Peter Zijlstra)

   - Implement the FUTEX2_NUMA ABI, which feature extends the futex
     interface to be NUMA-aware. On NUMA-aware futexes a second u32 word
     containing the NUMA node is added to after the u32 futex value word
     (Peter Zijlstra)

   - Implement the FUTEX2_MPOL ABI, which feature extends the futex
     interface to be mempolicy-aware as well, to further refine futex
     node mappings and lookups (Peter Zijlstra)

  Locking primitives:

   - Misc cleanups (Andy Shevchenko, Borislav Petkov, Colin Ian King,
     Ingo Molnar, Nam Cao, Peter Zijlstra)

  Lockdep:

   - Prevent abuse of lockdep subclasses (Waiman Long)

   - Add number of dynamic keys to /proc/lockdep_stats (Waiman Long)

  Plus misc cleanups and fixes"

* tag 'locking-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
  selftests/futex: Fix spelling mistake "unitiliazed" -> "uninitialized"
  futex: Correct the kernedoc return value for futex_wait_setup().
  tools headers: Synchronize prctl.h ABI header
  futex: Use RCU_INIT_POINTER() in futex_mm_init().
  selftests/futex: Use TAP output in futex_numa_mpol
  selftests/futex: Use TAP output in futex_priv_hash
  futex: Fix kernel-doc comments
  futex: Relax the rcu_assign_pointer() assignment of mm->futex_phash in futex_mm_init()
  futex: Fix outdated comment in struct restart_block
  locking/lockdep: Add number of dynamic keys to /proc/lockdep_stats
  locking/lockdep: Prevent abuse of lockdep subclass
  locking/lockdep: Move hlock_equal() to the respective #ifdeffery
  futex,selftests: Add another FUTEX2_NUMA selftest
  selftests/futex: Add futex_numa_mpol
  selftests/futex: Add futex_priv_hash
  selftests/futex: Build without headers nonsense
  tools/perf: Allow to select the number of hash buckets
  tools headers: Synchronize prctl.h ABI header
  futex: Implement FUTEX2_MPOL
  futex: Implement FUTEX2_NUMA
  ...
2025-05-26 14:42:07 -07:00
Linus Torvalds
7d7a103d29 vfs-6.16-rc1.pidfs
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Merge tag 'vfs-6.16-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull pidfs updates from Christian Brauner:
 "Features:

   - Allow handing out pidfds for reaped tasks for AF_UNIX SO_PEERPIDFD
     socket option

     SO_PEERPIDFD is a socket option that allows to retrieve a pidfd for
     the process that called connect() or listen(). This is heavily used
     to safely authenticate clients in userspace avoiding security bugs
     due to pid recycling races (dbus, polkit, systemd, etc.)

     SO_PEERPIDFD currently doesn't support handing out pidfds if the
     sk->sk_peer_pid thread-group leader has already been reaped. In
     this case it currently returns EINVAL. Userspace still wants to get
     a pidfd for a reaped process to have a stable handle it can pass
     on. This is especially useful now that it is possible to retrieve
     exit information through a pidfd via the PIDFD_GET_INFO ioctl()'s
     PIDFD_INFO_EXIT flag

     Another summary has been provided by David Rheinsberg:

      > A pidfd can outlive the task it refers to, and thus user-space
      > must already be prepared that the task underlying a pidfd is
      > gone at the time they get their hands on the pidfd. For
      > instance, resolving the pidfd to a PID via the fdinfo must be
      > prepared to read `-1`.
      >
      > Despite user-space knowing that a pidfd might be stale, several
      > kernel APIs currently add another layer that checks for this. In
      > particular, SO_PEERPIDFD returns `EINVAL` if the peer-task was
      > already reaped, but returns a stale pidfd if the task is reaped
      > immediately after the respective alive-check.
      >
      > This has the unfortunate effect that user-space now has two ways
      > to check for the exact same scenario: A syscall might return
      > EINVAL/ESRCH/... *or* the pidfd might be stale, even though
      > there is no particular reason to distinguish both cases. This
      > also propagates through user-space APIs, which pass on pidfds.
      > They must be prepared to pass on `-1` *or* the pidfd, because
      > there is no guaranteed way to get a stale pidfd from the kernel.
      >
      > Userspace must already deal with a pidfd referring to a reaped
      > task as the task may exit and get reaped at any time will there
      > are still many pidfds referring to it

     In order to allow handing out reaped pidfd SO_PEERPIDFD needs to
     ensure that PIDFD_INFO_EXIT information is available whenever a
     pidfd for a reaped task is created by PIDFD_INFO_EXIT. The uapi
     promises that reaped pidfds are only handed out if it is guaranteed
     that the caller sees the exit information:

     TEST_F(pidfd_info, success_reaped)
     {
             struct pidfd_info info = {
                     .mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT,
             };

             /*
              * Process has already been reaped and PIDFD_INFO_EXIT been set.
              * Verify that we can retrieve the exit status of the process.
              */
             ASSERT_EQ(ioctl(self->child_pidfd4, PIDFD_GET_INFO, &info), 0);
             ASSERT_FALSE(!!(info.mask & PIDFD_INFO_CREDS));
             ASSERT_TRUE(!!(info.mask & PIDFD_INFO_EXIT));
             ASSERT_TRUE(WIFEXITED(info.exit_code));
             ASSERT_EQ(WEXITSTATUS(info.exit_code), 0);
     }

     To hand out pidfds for reaped processes we thus allocate a pidfs
     entry for the relevant sk->sk_peer_pid at the time the
     sk->sk_peer_pid is stashed and drop it when the socket is
     destroyed. This guarantees that exit information will always be
     recorded for the sk->sk_peer_pid task and we can hand out pidfds
     for reaped processes

   - Hand a pidfd to the coredump usermode helper process

     Give userspace a way to instruct the kernel to install a pidfd for
     the crashing process into the process started as a usermode helper.
     There's still tricky race-windows that cannot be easily or
     sometimes not closed at all by userspace. There's various ways like
     looking at the start time of a process to make sure that the
     usermode helper process is started after the crashing process but
     it's all very very brittle and fraught with peril

     The crashed-but-not-reaped process can be killed by userspace
     before coredump processing programs like systemd-coredump have had
     time to manually open a PIDFD from the PID the kernel provides
     them, which means they can be tricked into reading from an
     arbitrary process, and they run with full privileges as they are
     usermode helper processes

     Even if that specific race-window wouldn't exist it's still the
     safest and cleanest way to let the kernel provide the pidfd
     directly instead of requiring userspace to do it manually. In
     parallel with this commit we already have systemd adding support
     for this in [1]

     When the usermode helper process is forked we install a pidfd file
     descriptor three into the usermode helper's file descriptor table
     so it's available to the exec'd program

     Since usermode helpers are either children of the system_unbound_wq
     workqueue or kthreadd we know that the file descriptor table is
     empty and can thus always use three as the file descriptor number

     Note, that we'll install a pidfd for the thread-group leader even
     if a subthread is calling do_coredump(). We know that task linkage
     hasn't been removed yet and even if this @current isn't the actual
     thread-group leader we know that the thread-group leader cannot be
     reaped until
     @current has exited

   - Allow telling when a task has not been found from finding the wrong
     task when creating a pidfd

     We currently report EINVAL whenever a struct pid has no tasked
     attached anymore thereby conflating two concepts:

      (1) The task has already been reaped

      (2) The caller requested a pidfd for a thread-group leader but the
          pid actually references a struct pid that isn't used as a
          thread-group leader

     This is causing issues for non-threaded workloads as in where they
     expect ESRCH to be reported, not EINVAL

     So allow userspace to reliably distinguish between (1) and (2)

   - Make it possible to detect when a pidfs entry would outlive the
     struct pid it pinned

   - Add a range of new selftests

  Cleanups:

   - Remove unneeded NULL check from pidfd_prepare() for passed struct
     pid

   - Avoid pointless reference count bump during release_task()

  Fixes:

   - Various fixes to the pidfd and coredump selftests

   - Fix error handling for replace_fd() when spawning coredump usermode
     helper"

* tag 'vfs-6.16-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  pidfs: detect refcount bugs
  coredump: hand a pidfd to the usermode coredump helper
  coredump: fix error handling for replace_fd()
  pidfs: move O_RDWR into pidfs_alloc_file()
  selftests: coredump: Raise timeout to 2 minutes
  selftests: coredump: Fix test failure for slow machines
  selftests: coredump: Properly initialize pointer
  net, pidfs: enable handing out pidfds for reaped sk->sk_peer_pid
  pidfs: get rid of __pidfd_prepare()
  net, pidfs: prepare for handing out pidfds for reaped sk->sk_peer_pid
  pidfs: register pid in pidfs
  net, pidfd: report EINVAL for ESRCH
  release_task: kill the no longer needed get/put_pid(thread_pid)
  pidfs: ensure consistent ENOENT/ESRCH reporting
  exit: move wake_up_all() pidfd waiters into __unhash_process()
  selftest/pidfd: add test for thread-group leader pidfd open for thread
  pidfd: improve uapi when task isn't found
  pidfd: remove unneeded NULL check from pidfd_prepare()
  selftests/pidfd: adapt to recent changes
2025-05-26 10:30:02 -07:00
Lorenzo Stoakes
3e43e260f1 mm: perform VMA allocation, freeing, duplication in mm
Right now these are performed in kernel/fork.c which is odd and a
violation of separation of concerns, as well as preventing us from
integrating this and related logic into userland VMA testing going
forward.

There is a fly in the ointment - nommu - mmap.c is not compiled if
CONFIG_MMU not set, and neither is vma.c.

To square the circle, let's add a new file - vma_init.c.  This will be
compiled for both CONFIG_MMU and nommu builds, and will also form part of
the VMA userland testing.

This allows us to de-duplicate code, while maintaining separation of
concerns and the ability for us to userland test this logic.

Update the VMA userland tests accordingly, additionally adding a
detach_free_vma() helper function to correctly detach VMAs before freeing
them in test code, as this change was triggering the assert for this.

[akpm@linux-foundation.org: remove stray newline, per Liam]
Link: https://lkml.kernel.org/r/f97b3a85a6da0196b28070df331b99e22b263be8.1745853549.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-12 23:50:48 -07:00
Lorenzo Stoakes
26a8f57760 mm: move dup_mmap() to mm
This is a key step in our being able to abstract and isolate VMA
allocation and destruction logic.

This function is the last one where vm_area_free() and vm_area_dup() are
directly referenced outside of mmap, so having this in mm allows us to
isolate these.

We do the same for the nommu version which is substantially simpler.

We place the declaration for dup_mmap() in mm/internal.h and have
kernel/fork.c import this in order to prevent improper use of this
functionality elsewhere in the kernel.

While we're here, we remove the useless #ifdef CONFIG_MMU check around
mmap_read_lock_maybe_expand() in mmap.c, mmap.c is compiled only if
CONFIG_MMU is set.

Link: https://lkml.kernel.org/r/e49aad3d00212f5539d9fa5769bfda4ce451db3e.1745853549.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Suggested-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-12 23:50:48 -07:00
David Hildenbrand
e9f180d7cf kernel/fork: only call untrack_pfn_clear() on VMAs duplicated for fork()
Not intuitive, but vm_area_dup() located in kernel/fork.c is not only used
for duplicating VMAs during fork(), but also for duplicating VMAs when
splitting VMAs or when mremap()'ing them.

VM_PFNMAP mappings can at least get ordinarily mremap()'ed (no change in
size) and apparently also shrunk during mremap(), which implies
duplicating the VMA in __split_vma() first.

In case of ordinary mremap() (no change in size), we first duplicate the
VMA in copy_vma_and_data()->copy_vma() to then call untrack_pfn_clear() on
the old VMA: we effectively move the VM_PAT reservation.  So the
untrack_pfn_clear() call on the new VMA duplicating is wrong in that
context.

Splitting of VMAs seems problematic, because we don't duplicate/adjust the
reservation when splitting the VMA.  Instead, in memtype_erase() -- called
during zapping/munmap -- we shrink a reservation in case only the end
address matches: Assume we split a VMA into A and B, both would share a
reservation until B is unmapped.

So when unmapping B, the reservation would be updated to cover only A. 
When unmapping A, we would properly remove the now-shrunk reservation. 
That scenario describes the mremap() shrinking (old_size > new_size),
where we split + unmap B, and the untrack_pfn_clear() on the new VMA when
is wrong.

What if we manage to split a VM_PFNMAP VMA into A and B and unmap A first?
It would be broken because we would never free the reservation.  Likely,
there are ways to trigger such a VMA split outside of mremap().

Affecting other VMA duplication was not intended, vm_area_dup() being used
outside of kernel/fork.c was an oversight.  So let's fix that for; how to
handle VMA splits better should be investigated separately.


With a simple reproducer that uses mprotect() to split such a VMA I can
trigger

x86/PAT: pat_mremap:26448 freeing invalid memtype [mem 0x00000000-0x00000fff]

Link: https://lkml.kernel.org/r/20250422144942.2871395-1-david@redhat.com
Fixes: dc84bc2aba ("x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-11 17:26:06 -07:00
Sebastian Andrzej Siewior
7c4f75a21f futex: Allow automatic allocation of process wide futex hash
Allocate a private futex hash with 16 slots if a task forks its first
thread.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-14-bigeasy@linutronix.de
2025-05-03 12:02:08 +02:00
Sebastian Andrzej Siewior
80367ad01d futex: Add basic infrastructure for local task local hash
The futex hash is system wide and shared by all tasks. Each slot
is hashed based on futex address and the VMA of the thread. Due to
randomized VMAs (and memory allocations) the same logical lock (pointer)
can end up in a different hash bucket on each invocation of the
application. This in turn means that different applications may share a
hash bucket on the first invocation but not on the second and it is not
always clear which applications will be involved. This can result in
high latency's to acquire the futex_hash_bucket::lock especially if the
lock owner is limited to a CPU and can not be effectively PI boosted.

Introduce basic infrastructure for process local hash which is shared by
all threads of process. This hash will only be used for a
PROCESS_PRIVATE FUTEX operation.

The hashmap can be allocated via:

        prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, num);

A `num' of 0 means that the global hash is used instead of a private
hash.
Other values for `num' specify the number of slots for the hash and the
number must be power of two, starting with two.
The prctl() returns zero on success. This function can only be used
before a thread is created.

The current status for the private hash can be queried via:

        num = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS);

which return the current number of slots. The value 0 means that the
global hash is used. Values greater than 0 indicate the number of slots
that are used. A negative number indicates an error.

For optimisation, for the private hash jhash2() uses only two arguments
the address and the offset. This omits the VMA which is always the same.

[peterz: Use 0 for global hash. A bit shuffling and renaming. ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-13-bigeasy@linutronix.de
2025-05-03 12:02:07 +02:00
Christian Brauner
a71f402acd
pidfs: get rid of __pidfd_prepare()
Fold it into pidfd_prepare() and rename PIDFD_CLONE to PIDFD_STALE to
indicate that the passed pid might not have task linkage and no explicit
check for that should be performed.

Link: https://lore.kernel.org/20250425-work-pidfs-net-v2-3-450a19461e75@kernel.org
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: David Rheinsberg <david@readahead.eu>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-04-26 08:28:03 +02:00
Christian Brauner
17f1b08acf
pidfs: ensure consistent ENOENT/ESRCH reporting
In a prior patch series we tried to cleanly differentiate between:

(1) The task has already been reaped.
(2) The caller requested a pidfd for a thread-group leader but the pid
    actually references a struct pid that isn't used as a thread-group
    leader.

as this was causing issues for non-threaded workloads.

But there's cases where the current simple logic is wrong. Specifically,
if the pid was a leader pid and the check races with __unhash_process().
Stabilize this by using the pidfd waitqueue lock.

Link: https://lore.kernel.org/20250411-work-pidfs-enoent-v2-2-60b2d3bb545f@kernel.org
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-04-12 14:04:53 +02:00
Christian Brauner
8cf4b738f6
pidfd: improve uapi when task isn't found
We currently report EINVAL whenever a struct pid has no tasked attached
anymore thereby conflating two concepts:

(1) The task has already been reaped.
(2) The caller requested a pidfd for a thread-group leader but the pid
    actually references a struct pid that isn't used as a thread-group
    leader.

This is causing issues for non-threaded workloads as in [1].

This patch tries to allow userspace to distinguish between (1) and (2).
This is racy of course but that shouldn't matter.

Link: https://github.com/systemd/systemd/pull/36982 [1]
Link: https://lore.kernel.org/r/20250403-work-pidfd-fixes-v1-3-a123b6ed6716@kernel.org
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-04-07 09:38:24 +02:00
Christian Brauner
1b090949c9
pidfd: remove unneeded NULL check from pidfd_prepare()
None of the caller actually pass a NULL pid in there.

Link: https://lore.kernel.org/r/20250403-work-pidfd-fixes-v1-2-a123b6ed6716@kernel.org
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-04-07 09:38:24 +02:00
Linus Torvalds
d6b02199cd - The 7 patch series "powerpc/crash: use generic crashkernel
reservation" from Sourabh Jain changes powerpc's kexec code to use more
   of the generic layers.
 
 - The 2 patch series "get_maintainer: report subsystem status
   separately" from Vlastimil Babka makes some long-requested improvements
   to the get_maintainer output.
 
 - The 4 patch series "ucount: Simplify refcounting with rcuref_t" from
   Sebastian Siewior cleans up and optimizing the refcounting in the ucount
   code.
 
 - The 12 patch series "reboot: support runtime configuration of
   emergency hw_protection action" from Ahmad Fatoum improves the ability
   for a driver to perform an emergency system shutdown or reboot.
 
 - The 16 patch series "Converge on using secs_to_jiffies() part two"
   from Easwar Hariharan performs further migrations from
   msecs_to_jiffies() to secs_to_jiffies().
 
 - The 7 patch series "lib/interval_tree: add some test cases and
   cleanup" from Wei Yang permits more userspace testing of kernel library
   code, adds some more tests and performs some cleanups.
 
 - The 2 patch series "hung_task: Dump the blocking task stacktrace" from
   Masami Hiramatsu arranges for the hung_task detector to dump the stack
   of the blocking task and not just that of the blocked task.
 
 - The 4 patch series "resource: Split and use DEFINE_RES*() macros" from
   Andy Shevchenko provides some cleanups to the resource definition
   macros.
 
 - Plus the usual shower of singleton patches - please see the individual
   changelogs for details.
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Merge tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - The series "powerpc/crash: use generic crashkernel reservation" from
   Sourabh Jain changes powerpc's kexec code to use more of the generic
   layers.

 - The series "get_maintainer: report subsystem status separately" from
   Vlastimil Babka makes some long-requested improvements to the
   get_maintainer output.

 - The series "ucount: Simplify refcounting with rcuref_t" from
   Sebastian Siewior cleans up and optimizing the refcounting in the
   ucount code.

 - The series "reboot: support runtime configuration of emergency
   hw_protection action" from Ahmad Fatoum improves the ability for a
   driver to perform an emergency system shutdown or reboot.

 - The series "Converge on using secs_to_jiffies() part two" from Easwar
   Hariharan performs further migrations from msecs_to_jiffies() to
   secs_to_jiffies().

 - The series "lib/interval_tree: add some test cases and cleanup" from
   Wei Yang permits more userspace testing of kernel library code, adds
   some more tests and performs some cleanups.

 - The series "hung_task: Dump the blocking task stacktrace" from Masami
   Hiramatsu arranges for the hung_task detector to dump the stack of
   the blocking task and not just that of the blocked task.

 - The series "resource: Split and use DEFINE_RES*() macros" from Andy
   Shevchenko provides some cleanups to the resource definition macros.

 - Plus the usual shower of singleton patches - please see the
   individual changelogs for details.

* tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits)
  mailmap: consolidate email addresses of Alexander Sverdlin
  fs/procfs: fix the comment above proc_pid_wchan()
  relay: use kasprintf() instead of fixed buffer formatting
  resource: replace open coded variant of DEFINE_RES()
  resource: replace open coded variants of DEFINE_RES_*_NAMED()
  resource: replace open coded variant of DEFINE_RES_NAMED_DESC()
  resource: split DEFINE_RES_NAMED_DESC() out of DEFINE_RES_NAMED()
  samples: add hung_task detector mutex blocking sample
  hung_task: show the blocker task if the task is hung on mutex
  kexec_core: accept unaccepted kexec segments' destination addresses
  watchdog/perf: optimize bytes copied and remove manual NUL-termination
  lib/interval_tree: fix the comment of interval_tree_span_iter_next_gap()
  lib/interval_tree: skip the check before go to the right subtree
  lib/interval_tree: add test case for span iteration
  lib/interval_tree: add test case for interval_tree_iter_xxx() helpers
  lib/rbtree: add random seed
  lib/rbtree: split tests
  lib/rbtree: enable userland test suite for rbtree related data structure
  checkpatch: describe --min-conf-desc-length
  scripts/gdb/symbols: determine KASLR offset on s390
  ...
2025-04-01 10:06:52 -07:00
Linus Torvalds
eb0ece1602 - The 6 patch series "Enable strict percpu address space checks" from
Uros Bizjak uses x86 named address space qualifiers to provide
   compile-time checking of percpu area accesses.
 
   This has caused a small amount of fallout - two or three issues were
   reported.  In all cases the calling code was founf to be incorrect.
 
 - The 4 patch series "Some cleanup for memcg" from Chen Ridong
   implements some relatively monir cleanups for the memcontrol code.
 
 - The 17 patch series "mm: fixes for device-exclusive entries (hmm)"
   from David Hildenbrand fixes a boatload of issues which David found then
   using device-exclusive PTE entries when THP is enabled.  More work is
   needed, but this makes thins better - our own HMM selftests now succeed.
 
 - The 2 patch series "mm: zswap: remove z3fold and zbud" from Yosry
   Ahmed remove the z3fold and zbud implementations.  They have been
   deprecated for half a year and nobody has complained.
 
 - The 5 patch series "mm: further simplify VMA merge operation" from
   Lorenzo Stoakes implements numerous simplifications in this area.  No
   runtime effects are anticipated.
 
 - The 4 patch series "mm/madvise: remove redundant mmap_lock operations
   from process_madvise()" from SeongJae Park rationalizes the locking in
   the madvise() implementation.  Performance gains of 20-25% were observed
   in one MADV_DONTNEED microbenchmark.
 
 - The 12 patch series "Tiny cleanup and improvements about SWAP code"
   from Baoquan He contains a number of touchups to issues which Baoquan
   noticed when working on the swap code.
 
 - The 2 patch series "mm: kmemleak: Usability improvements" from Catalin
   Marinas implements a couple of improvements to the kmemleak user-visible
   output.
 
 - The 2 patch series "mm/damon/paddr: fix large folios access and
   schemes handling" from Usama Arif provides a couple of fixes for DAMON's
   handling of large folios.
 
 - The 3 patch series "mm/damon/core: fix wrong and/or useless
   damos_walk() behaviors" from SeongJae Park fixes a few issues with the
   accuracy of kdamond's walking of DAMON regions.
 
 - The 3 patch series "expose mapping wrprotect, fix fb_defio use" from
   Lorenzo Stoakes changes the interaction between framebuffer deferred-io
   and core MM.  No functional changes are anticipated - this is
   preparatory work for the future removal of page structure fields.
 
 - The 4 patch series "mm/damon: add support for hugepage_size DAMOS
   filter" from Usama Arif adds a DAMOS filter which permits the filtering
   by huge page sizes.
 
 - The 4 patch series "mm: permit guard regions for file-backed/shmem
   mappings" from Lorenzo Stoakes extends the guard region feature from its
   present "anon mappings only" state.  The feature now covers shmem and
   file-backed mappings.
 
 - The 4 patch series "mm: batched unmap lazyfree large folios during
   reclamation" from Barry Song cleans up and speeds up the unmapping for
   pte-mapped large folios.
 
 - The 18 patch series "reimplement per-vma lock as a refcount" from
   Suren Baghdasaryan puts the vm_lock back into the vma.  Our reasons for
   pulling it out were largely bogus and that change made the code more
   messy.  This patchset provides small (0-10%) improvements on one
   microbenchmark.
 
 - The 5 patch series "Docs/mm/damon: misc DAMOS filters documentation
   fixes and improves" from SeongJae Park does some maintenance work on the
   DAMON docs.
 
 - The 27 patch series "hugetlb/CMA improvements for large systems" from
   Frank van der Linden addresses a pile of issues which have been observed
   when using CMA on large machines.
 
 - The 2 patch series "mm/damon: introduce DAMOS filter type for unmapped
   pages" from SeongJae Park enables users of DMAON/DAMOS to filter my the
   page's mapped/unmapped status.
 
 - The 19 patch series "zsmalloc/zram: there be preemption" from Sergey
   Senozhatsky teaches zram to run its compression and decompression
   operations preemptibly.
 
 - The 12 patch series "selftests/mm: Some cleanups from trying to run
   them" from Brendan Jackman fixes a pile of unrelated issues which
   Brendan encountered while runnimg our selftests.
 
 - The 2 patch series "fs/proc/task_mmu: add guard region bit to pagemap"
   from Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
   determine whether a particular page is a guard page.
 
 - The 7 patch series "mm, swap: remove swap slot cache" from Kairui Song
   removes the swap slot cache from the allocation path - it simply wasn't
   being effective.
 
 - The 5 patch series "mm: cleanups for device-exclusive entries (hmm)"
   from David Hildenbrand implements a number of unrelated cleanups in this
   code.
 
 - The 5 patch series "mm: Rework generic PTDUMP configs" from Anshuman
   Khandual implements a number of preparatoty cleanups to the
   GENERIC_PTDUMP Kconfig logic.
 
 - The 8 patch series "mm/damon: auto-tune aggregation interval" from
   SeongJae Park implements a feedback-driven automatic tuning feature for
   DAMON's aggregation interval tuning.
 
 - The 5 patch series "Fix lazy mmu mode" from Ryan Roberts fixes some
   issues in powerpc, sparc and x86 lazy MMU implementations.  Ryan did
   this in preparation for implementing lazy mmu mode for arm64 to optimize
   vmalloc.
 
 - The 2 patch series "mm/page_alloc: Some clarifications for migratetype
   fallback" from Brendan Jackman reworks some commentary to make the code
   easier to follow.
 
 - The 3 patch series "page_counter cleanup and size reduction" from
   Shakeel Butt cleans up the page_counter code and fixes a size increase
   which we accidentally added late last year.
 
 - The 3 patch series "Add a command line option that enables control of
   how many threads should be used to allocate huge pages" from Thomas
   Prescher does that.  It allows the careful operator to significantly
   reduce boot time by tuning the parallalization of huge page
   initialization.
 
 - The 3 patch series "Fix calculations in trace_balance_dirty_pages()
   for cgwb" from Tang Yizhou fixes the tracing output from the dirty page
   balancing code.
 
 - The 9 patch series "mm/damon: make allow filters after reject filters
   useful and intuitive" from SeongJae Park improves the handling of allow
   and reject filters.  Behaviour is made more consistent and the
   documention is updated accordingly.
 
 - The 5 patch series "Switch zswap to object read/write APIs" from Yosry
   Ahmed updates zswap to the new object read/write APIs and thus permits
   the removal of some legacy code from zpool and zsmalloc.
 
 - The 6 patch series "Some trivial cleanups for shmem" from Baolin Wang
   does as it claims.
 
 - The 20 patch series "fs/dax: Fix ZONE_DEVICE page reference counts"
   from Alistair Popple regularizes the weird ZONE_DEVICE page refcount
   handling in DAX, permittig the removal of a number of special-case
   checks.
 
 - The 4 patch series "refactor mremap and fix bug" from Lorenzo Stoakes
   is a preparatoty refactoring and cleanup of the mremap() code.
 
 - The 20 patch series "mm: MM owner tracking for large folios (!hugetlb)
   + CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
   which we determine whether a large folio is known to be mapped
   exclusively into a single MM.
 
 - The 8 patch series "mm/damon: add sysfs dirs for managing DAMOS
   filters based on handling layers" from SeongJae Park adds a couple of
   new sysfs directories to ease the management of DAMON/DAMOS filters.
 
 - The 13 patch series "arch, mm: reduce code duplication in mem_init()"
   from Mike Rapoport consolidates many per-arch implementations of
   mem_init() into code generic code, where that is practical.
 
 - The 13 patch series "mm/damon/sysfs: commit parameters online via
   damon_call()" from SeongJae Park continues the cleaning up of sysfs
   access to DAMON internal data.
 
 - The 3 patch series "mm: page_ext: Introduce new iteration API" from
   Luiz Capitulino reworks the page_ext initialization to fix a boot-time
   crash which was observed with an unusual combination of compile and
   cmdline options.
 
 - The 8 patch series "Buddy allocator like (or non-uniform) folio split"
   from Zi Yan reworks the code to split a folio into smaller folios.  The
   main benefit is lessened memory consumption: fewer post-split folios are
   generated.
 
 - The 2 patch series "Minimize xa_node allocation during xarry split"
   from Zi Yan reduces the number of xarray xa_nodes which are generated
   during an xarray split.
 
 - The 2 patch series "drivers/base/memory: Two cleanups" from Gavin Shan
   performs some maintenance work on the drivers/base/memory code.
 
 - The 3 patch series "Add tracepoints for lowmem reserves, watermarks
   and totalreserve_pages" from Martin Liu adds some more tracepoints to
   the page allocator code.
 
 - The 4 patch series "mm/madvise: cleanup requests validations and
   classifications" from SeongJae Park cleans up some warts which SeongJae
   observed during his earlier madvise work.
 
 - The 3 patch series "mm/hwpoison: Fix regressions in memory failure
   handling" from Shuai Xue addresses two quite serious regressions which
   Shuai has observed in the memory-failure implementation.
 
 - The 5 patch series "mm: reliable huge page allocator" from Johannes
   Weiner makes huge page allocations cheaper and more reliable by reducing
   fragmentation.
 
 - The 5 patch series "Minor memcg cleanups & prep for memdescs" from
   Matthew Wilcox is preparatory work for the future implementation of
   memdescs.
 
 - The 4 patch series "track memory used by balloon drivers" from Nico
   Pache introduces a way to track memory used by our various balloon
   drivers.
 
 - The 2 patch series "mm/damon: introduce DAMOS filter type for active
   pages" from Nhat Pham permits users to filter for active/inactive pages,
   separately for file and anon pages.
 
 - The 2 patch series "Adding Proactive Memory Reclaim Statistics" from
   Hao Jia separates the proactive reclaim statistics from the direct
   reclaim statistics.
 
 - The 2 patch series "mm/vmscan: don't try to reclaim hwpoison folio"
   from Jinjiang Tu fixes our handling of hwpoisoned pages within the
   reclaim code.
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Merge tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - The series "Enable strict percpu address space checks" from Uros
   Bizjak uses x86 named address space qualifiers to provide
   compile-time checking of percpu area accesses.

   This has caused a small amount of fallout - two or three issues were
   reported. In all cases the calling code was found to be incorrect.

 - The series "Some cleanup for memcg" from Chen Ridong implements some
   relatively monir cleanups for the memcontrol code.

 - The series "mm: fixes for device-exclusive entries (hmm)" from David
   Hildenbrand fixes a boatload of issues which David found then using
   device-exclusive PTE entries when THP is enabled. More work is
   needed, but this makes thins better - our own HMM selftests now
   succeed.

 - The series "mm: zswap: remove z3fold and zbud" from Yosry Ahmed
   remove the z3fold and zbud implementations. They have been deprecated
   for half a year and nobody has complained.

 - The series "mm: further simplify VMA merge operation" from Lorenzo
   Stoakes implements numerous simplifications in this area. No runtime
   effects are anticipated.

 - The series "mm/madvise: remove redundant mmap_lock operations from
   process_madvise()" from SeongJae Park rationalizes the locking in the
   madvise() implementation. Performance gains of 20-25% were observed
   in one MADV_DONTNEED microbenchmark.

 - The series "Tiny cleanup and improvements about SWAP code" from
   Baoquan He contains a number of touchups to issues which Baoquan
   noticed when working on the swap code.

 - The series "mm: kmemleak: Usability improvements" from Catalin
   Marinas implements a couple of improvements to the kmemleak
   user-visible output.

 - The series "mm/damon/paddr: fix large folios access and schemes
   handling" from Usama Arif provides a couple of fixes for DAMON's
   handling of large folios.

 - The series "mm/damon/core: fix wrong and/or useless damos_walk()
   behaviors" from SeongJae Park fixes a few issues with the accuracy of
   kdamond's walking of DAMON regions.

 - The series "expose mapping wrprotect, fix fb_defio use" from Lorenzo
   Stoakes changes the interaction between framebuffer deferred-io and
   core MM. No functional changes are anticipated - this is preparatory
   work for the future removal of page structure fields.

 - The series "mm/damon: add support for hugepage_size DAMOS filter"
   from Usama Arif adds a DAMOS filter which permits the filtering by
   huge page sizes.

 - The series "mm: permit guard regions for file-backed/shmem mappings"
   from Lorenzo Stoakes extends the guard region feature from its
   present "anon mappings only" state. The feature now covers shmem and
   file-backed mappings.

 - The series "mm: batched unmap lazyfree large folios during
   reclamation" from Barry Song cleans up and speeds up the unmapping
   for pte-mapped large folios.

 - The series "reimplement per-vma lock as a refcount" from Suren
   Baghdasaryan puts the vm_lock back into the vma. Our reasons for
   pulling it out were largely bogus and that change made the code more
   messy. This patchset provides small (0-10%) improvements on one
   microbenchmark.

 - The series "Docs/mm/damon: misc DAMOS filters documentation fixes and
   improves" from SeongJae Park does some maintenance work on the DAMON
   docs.

 - The series "hugetlb/CMA improvements for large systems" from Frank
   van der Linden addresses a pile of issues which have been observed
   when using CMA on large machines.

 - The series "mm/damon: introduce DAMOS filter type for unmapped pages"
   from SeongJae Park enables users of DMAON/DAMOS to filter my the
   page's mapped/unmapped status.

 - The series "zsmalloc/zram: there be preemption" from Sergey
   Senozhatsky teaches zram to run its compression and decompression
   operations preemptibly.

 - The series "selftests/mm: Some cleanups from trying to run them" from
   Brendan Jackman fixes a pile of unrelated issues which Brendan
   encountered while runnimg our selftests.

 - The series "fs/proc/task_mmu: add guard region bit to pagemap" from
   Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
   determine whether a particular page is a guard page.

 - The series "mm, swap: remove swap slot cache" from Kairui Song
   removes the swap slot cache from the allocation path - it simply
   wasn't being effective.

 - The series "mm: cleanups for device-exclusive entries (hmm)" from
   David Hildenbrand implements a number of unrelated cleanups in this
   code.

 - The series "mm: Rework generic PTDUMP configs" from Anshuman Khandual
   implements a number of preparatoty cleanups to the GENERIC_PTDUMP
   Kconfig logic.

 - The series "mm/damon: auto-tune aggregation interval" from SeongJae
   Park implements a feedback-driven automatic tuning feature for
   DAMON's aggregation interval tuning.

 - The series "Fix lazy mmu mode" from Ryan Roberts fixes some issues in
   powerpc, sparc and x86 lazy MMU implementations. Ryan did this in
   preparation for implementing lazy mmu mode for arm64 to optimize
   vmalloc.

 - The series "mm/page_alloc: Some clarifications for migratetype
   fallback" from Brendan Jackman reworks some commentary to make the
   code easier to follow.

 - The series "page_counter cleanup and size reduction" from Shakeel
   Butt cleans up the page_counter code and fixes a size increase which
   we accidentally added late last year.

 - The series "Add a command line option that enables control of how
   many threads should be used to allocate huge pages" from Thomas
   Prescher does that. It allows the careful operator to significantly
   reduce boot time by tuning the parallalization of huge page
   initialization.

 - The series "Fix calculations in trace_balance_dirty_pages() for cgwb"
   from Tang Yizhou fixes the tracing output from the dirty page
   balancing code.

 - The series "mm/damon: make allow filters after reject filters useful
   and intuitive" from SeongJae Park improves the handling of allow and
   reject filters. Behaviour is made more consistent and the documention
   is updated accordingly.

 - The series "Switch zswap to object read/write APIs" from Yosry Ahmed
   updates zswap to the new object read/write APIs and thus permits the
   removal of some legacy code from zpool and zsmalloc.

 - The series "Some trivial cleanups for shmem" from Baolin Wang does as
   it claims.

 - The series "fs/dax: Fix ZONE_DEVICE page reference counts" from
   Alistair Popple regularizes the weird ZONE_DEVICE page refcount
   handling in DAX, permittig the removal of a number of special-case
   checks.

 - The series "refactor mremap and fix bug" from Lorenzo Stoakes is a
   preparatoty refactoring and cleanup of the mremap() code.

 - The series "mm: MM owner tracking for large folios (!hugetlb) +
   CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
   which we determine whether a large folio is known to be mapped
   exclusively into a single MM.

 - The series "mm/damon: add sysfs dirs for managing DAMOS filters based
   on handling layers" from SeongJae Park adds a couple of new sysfs
   directories to ease the management of DAMON/DAMOS filters.

 - The series "arch, mm: reduce code duplication in mem_init()" from
   Mike Rapoport consolidates many per-arch implementations of
   mem_init() into code generic code, where that is practical.

 - The series "mm/damon/sysfs: commit parameters online via
   damon_call()" from SeongJae Park continues the cleaning up of sysfs
   access to DAMON internal data.

 - The series "mm: page_ext: Introduce new iteration API" from Luiz
   Capitulino reworks the page_ext initialization to fix a boot-time
   crash which was observed with an unusual combination of compile and
   cmdline options.

 - The series "Buddy allocator like (or non-uniform) folio split" from
   Zi Yan reworks the code to split a folio into smaller folios. The
   main benefit is lessened memory consumption: fewer post-split folios
   are generated.

 - The series "Minimize xa_node allocation during xarry split" from Zi
   Yan reduces the number of xarray xa_nodes which are generated during
   an xarray split.

 - The series "drivers/base/memory: Two cleanups" from Gavin Shan
   performs some maintenance work on the drivers/base/memory code.

 - The series "Add tracepoints for lowmem reserves, watermarks and
   totalreserve_pages" from Martin Liu adds some more tracepoints to the
   page allocator code.

 - The series "mm/madvise: cleanup requests validations and
   classifications" from SeongJae Park cleans up some warts which
   SeongJae observed during his earlier madvise work.

 - The series "mm/hwpoison: Fix regressions in memory failure handling"
   from Shuai Xue addresses two quite serious regressions which Shuai
   has observed in the memory-failure implementation.

 - The series "mm: reliable huge page allocator" from Johannes Weiner
   makes huge page allocations cheaper and more reliable by reducing
   fragmentation.

 - The series "Minor memcg cleanups & prep for memdescs" from Matthew
   Wilcox is preparatory work for the future implementation of memdescs.

 - The series "track memory used by balloon drivers" from Nico Pache
   introduces a way to track memory used by our various balloon drivers.

 - The series "mm/damon: introduce DAMOS filter type for active pages"
   from Nhat Pham permits users to filter for active/inactive pages,
   separately for file and anon pages.

 - The series "Adding Proactive Memory Reclaim Statistics" from Hao Jia
   separates the proactive reclaim statistics from the direct reclaim
   statistics.

 - The series "mm/vmscan: don't try to reclaim hwpoison folio" from
   Jinjiang Tu fixes our handling of hwpoisoned pages within the reclaim
   code.

* tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (431 commits)
  mm/page_alloc: remove unnecessary __maybe_unused in order_to_pindex()
  x86/mm: restore early initialization of high_memory for 32-bits
  mm/vmscan: don't try to reclaim hwpoison folio
  mm/hwpoison: introduce folio_contain_hwpoisoned_page() helper
  cgroup: docs: add pswpin and pswpout items in cgroup v2 doc
  mm: vmscan: split proactive reclaim statistics from direct reclaim statistics
  selftests/mm: speed up split_huge_page_test
  selftests/mm: uffd-unit-tests support for hugepages > 2M
  docs/mm/damon/design: document active DAMOS filter type
  mm/damon: implement a new DAMOS filter type for active pages
  fs/dax: don't disassociate zero page entries
  MM documentation: add "Unaccepted" meminfo entry
  selftests/mm: add commentary about 9pfs bugs
  fork: use __vmalloc_node() for stack allocation
  docs/mm: Physical Memory: Populate the "Zones" section
  xen: balloon: update the NR_BALLOON_PAGES state
  hv_balloon: update the NR_BALLOON_PAGES state
  balloon_compaction: update the NR_BALLOON_PAGES state
  meminfo: add a per node counter for balloon drivers
  mm: remove references to folio in __memcg_kmem_uncharge_page()
  ...
2025-04-01 09:29:18 -07:00
Linus Torvalds
7405c0f01a Miscellaneous x86 fixes and updates:
- Fix a large number of x86 Kconfig dependency and help text accuracy
    bugs/problems, by Mateusz Jończyk and David Heideberg.
 
  - Fix a VM_PAT interaction with fork() crash. This also touches
    core kernel code.
 
  - Fix an ORC unwinder bug for interrupt entries
 
  - Fixes and cleanups.
 
  - Fix an AMD microcode loader bug that can promote verification failures
    into success.
 
  - Add early-printk support for MMIO based UARTs on an x86 board that
    had no other serial debugging facility and also experienced early
    boot crashes.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-urgent-2025-03-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc x86 fixes and updates from Ingo Molnar:

 - Fix a large number of x86 Kconfig dependency and help text accuracy
   bugs/problems, by Mateusz Jończyk and David Heideberg

 - Fix a VM_PAT interaction with fork() crash. This also touches core
   kernel code

 - Fix an ORC unwinder bug for interrupt entries

 - Fixes and cleanups

 - Fix an AMD microcode loader bug that can promote verification
   failures into success

 - Add early-printk support for MMIO based UARTs on an x86 board that
   had no other serial debugging facility and also experienced early
   boot crashes

* tag 'x86-urgent-2025-03-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode/AMD: Fix __apply_microcode_amd()'s return value
  x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()
  x86/fpu: Update the outdated comment above fpstate_init_user()
  x86/early_printk: Add support for MMIO-based UARTs
  x86/dumpstack: Fix inaccurate unwinding from exception stacks due to misplaced assignment
  x86/entry: Fix ORC unwinder for PUSH_REGS with save_ret=1
  x86/Kconfig: Fix lists in X86_EXTENDED_PLATFORM help text
  x86/Kconfig: Correct X86_X2APIC help text
  x86/speculation: Remove the extra #ifdef around CALL_NOSPEC
  x86/Kconfig: Document release year of glibc 2.3.3
  x86/Kconfig: Make CONFIG_PCI_CNB20LE_QUIRK depend on X86_32
  x86/Kconfig: Document CONFIG_PCI_MMCONFIG
  x86/Kconfig: Update lists in X86_EXTENDED_PLATFORM
  x86/Kconfig: Move all X86_EXTENDED_PLATFORM options together
  x86/Kconfig: Always enable ARCH_SPARSEMEM_ENABLE
  x86/Kconfig: Enable X86_X2APIC by default and improve help text
2025-03-30 15:25:15 -07:00
David Hildenbrand
dc84bc2aba x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()
If track_pfn_copy() fails, we already added the dst VMA to the maple
tree. As fork() fails, we'll cleanup the maple tree, and stumble over
the dst VMA for which we neither performed any reservation nor copied
any page tables.

Consequently untrack_pfn() will see VM_PAT and try obtaining the
PAT information from the page table -- which fails because the page
table was not copied.

The easiest fix would be to simply clear the VM_PAT flag of the dst VMA
if track_pfn_copy() fails. However, the whole thing is about "simply"
clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy()
and performed a reservation, but copying the page tables fails, we'll
simply clear the VM_PAT flag, not properly undoing the reservation ...
which is also wrong.

So let's fix it properly: set the VM_PAT flag only if the reservation
succeeded (leaving it clear initially), and undo the reservation if
anything goes wrong while copying the page tables: clearing the VM_PAT
flag after undoing the reservation.

Note that any copied page table entries will get zapped when the VMA will
get removed later, after copy_page_range() succeeded; as VM_PAT is not set
then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be
happy. Note that leaving these page tables in place without a reservation
is not a problem, as we are aborting fork(); this process will never run.

A reproducer can trigger this usually at the first try:

  https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c

  WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110
  Modules linked in: ...
  CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
  RIP: 0010:get_pat_info+0xf6/0x110
  ...
  Call Trace:
   <TASK>
   ...
   untrack_pfn+0x52/0x110
   unmap_single_vma+0xa6/0xe0
   unmap_vmas+0x105/0x1f0
   exit_mmap+0xf6/0x460
   __mmput+0x4b/0x120
   copy_process+0x1bf6/0x2aa0
   kernel_clone+0xab/0x440
   __do_sys_clone+0x66/0x90
   do_syscall_64+0x95/0x180

Likely this case was missed in:

  d155df53f3 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed")

... and instead of undoing the reservation we simply cleared the VM_PAT flag.

Keep the documentation of these functions in include/linux/pgtable.h,
one place is more than sufficient -- we should clean that up for the other
functions like track_pfn_remap/untrack_pfn separately.

Fixes: d155df53f3 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed")
Fixes: 2ab640379a ("x86: PAT: hooks in generic vm code to help archs to track pfnmap regions - v3")
Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yuxin wang <wang1315768607@163.com>
Reported-by: Marius Fleischer <fleischermarius@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20250321112323.153741-1-david@redhat.com
Closes: https://lore.kernel.org/lkml/CABOYnLx_dnqzpCW99G81DmOr+2UzdmZMk=T3uxwNxwz+R1RAwg@mail.gmail.com/
Closes: https://lore.kernel.org/lkml/CAJg=8jwijTP5fre8woS4JVJQ8iUA6v+iNcsOgtj9Zfpc3obDOQ@mail.gmail.com/
2025-03-25 22:35:14 +01:00
Linus Torvalds
a50b4fe095 A treewide hrtimer timer cleanup
hrtimers are initialized with hrtimer_init() and a subsequent store to
   the callback pointer. This turned out to be suboptimal for the upcoming
   Rust integration and is obviously a silly implementation to begin with.
 
   This cleanup replaces the hrtimer_init(T); T->function = cb; sequence
   with hrtimer_setup(T, cb);
 
   The conversion was done with Coccinelle and a few manual fixups.
 
   Once the conversion has completely landed in mainline, hrtimer_init()
   will be removed and the hrtimer::function becomes a private member.
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Merge tag 'timers-cleanups-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer cleanups from Thomas Gleixner:
 "A treewide hrtimer timer cleanup

  hrtimers are initialized with hrtimer_init() and a subsequent store to
  the callback pointer. This turned out to be suboptimal for the
  upcoming Rust integration and is obviously a silly implementation to
  begin with.

  This cleanup replaces the hrtimer_init(T); T->function = cb; sequence
  with hrtimer_setup(T, cb);

  The conversion was done with Coccinelle and a few manual fixups.

  Once the conversion has completely landed in mainline, hrtimer_init()
  will be removed and the hrtimer::function becomes a private member"

* tag 'timers-cleanups-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (100 commits)
  wifi: rt2x00: Switch to use hrtimer_update_function()
  io_uring: Use helper function hrtimer_update_function()
  serial: xilinx_uartps: Use helper function hrtimer_update_function()
  ASoC: fsl: imx-pcm-fiq: Switch to use hrtimer_setup()
  RDMA: Switch to use hrtimer_setup()
  virtio: mem: Switch to use hrtimer_setup()
  drm/vmwgfx: Switch to use hrtimer_setup()
  drm/xe/oa: Switch to use hrtimer_setup()
  drm/vkms: Switch to use hrtimer_setup()
  drm/msm: Switch to use hrtimer_setup()
  drm/i915/request: Switch to use hrtimer_setup()
  drm/i915/uncore: Switch to use hrtimer_setup()
  drm/i915/pmu: Switch to use hrtimer_setup()
  drm/i915/perf: Switch to use hrtimer_setup()
  drm/i915/gvt: Switch to use hrtimer_setup()
  drm/i915/huc: Switch to use hrtimer_setup()
  drm/amdgpu: Switch to use hrtimer_setup()
  stm class: heartbeat: Switch to use hrtimer_setup()
  i2c: Switch to use hrtimer_setup()
  iio: Switch to use hrtimer_setup()
  ...
2025-03-25 10:54:15 -07:00
Uladzislau Rezki (Sony)
b25bcabb6c fork: use __vmalloc_node() for stack allocation
Replace __vmalloc_node_range() by __vmalloc_node().  The last variant
requires less parameters and it uses exactly the same arguments which are
partly now hidden inside __vmalloc_node().

This change does not change any functionality.  It makes the code a bit
simpler.

Link: https://lkml.kernel.org/r/20250317163614.166502-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-21 22:03:14 -07:00
Christian Brauner
68db272741
pidfs: ensure that PIDFS_INFO_EXIT is available
When we currently create a pidfd we check that the task hasn't been
reaped right before we create the pidfd. But it is of course possible
that by the time we return the pidfd to userspace the task has already
been reaped since we don't check again after having created a dentry for
it.

This was fine until now because that race was meaningless. But now that
we provide PIDFD_INFO_EXIT it is a problem because it is possible that
the kernel returns a reaped pidfd and it depends on the race whether
PIDFD_INFO_EXIT information is available. This depends on if the task
gets reaped before or after a dentry has been attached to struct pid.

Make this consistent and only returned pidfds for reaped tasks if
PIDFD_INFO_EXIT information is available. This is done by performing
another check whether the task has been reaped right after we attached a
dentry to struct pid.

Since pidfs_exit() is called before struct pid's task linkage is removed
the case where the task got reaped but a dentry was already attached to
struct pid and exit information was recorded and published can be
handled correctly. In that case we do return a pidfd for a reaped task
like we would've before.

Link: https://lore.kernel.org/r/20250316-kabel-fehden-66bdb6a83436@brauner
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-03-19 14:40:18 +01:00
David Hildenbrand
6af8cb80d3 mm/rmap: basic MM owner tracking for large folios (!hugetlb)
For small folios, we traditionally use the mapcount to decide whether it
was "certainly mapped exclusively" by a single MM (mapcount == 1) or
whether it "maybe mapped shared" by multiple MMs (mapcount > 1).  For
PMD-sized folios that were PMD-mapped, we were able to use a similar
mechanism (single PMD mapping), but for PTE-mapped folios and in the
future folios that span multiple PMDs, this does not work.

So we need a different mechanism to handle large folios.  Let's add a new
mechanism to detect whether a large folio is "certainly mapped
exclusively", or whether it is "maybe mapped shared".

We'll use this information next to optimize CoW reuse for PTE-mapped
anonymous THP, and to convert folio_likely_mapped_shared() to
folio_maybe_mapped_shared(), independent of per-page mapcounts.

For each large folio, we'll have two slots, whereby a slot stores:
 (1) an MM id: unique id assigned to each MM
 (2) a per-MM mapcount

If a slot is unoccupied, it can be taken by the next MM that maps folio
page.

In addition, we'll remember the current state -- "mapped exclusively" vs. 
"maybe mapped shared" -- and use a bit spinlock to sync on updates and to
reduce the total number of atomic accesses on updates.  In the future, it
might be possible to squeeze a proper spinlock into "struct folio".  For
now, keep it simple, as we require the whole thing with THP only, that is
incompatible with RT.

As we have to squeeze this information into the "struct folio" of even
folios of order-1 (2 pages), and we generally want to reduce the required
metadata, we'll assign each MM a unique ID that can fit into an int.  In
total, we can squeeze everything into 4x int (2x long) on 64bit.

32bit support is a bit challenging, because we only have 2x long == 2x int
in order-1 folios.  But we can make it work for now, because we neither
expect many MMs nor very large folios on 32bit.

We will reliably detect folios as "mapped exclusively" vs.  "mapped
shared" as long as only two MMs map pages of a folio at one point in time
-- for example with fork() and short-lived child processes, or with apps
that hand over state from one instance to another.

As soon as three MMs are involved at the same time, we might detect "maybe
mapped shared" although the folio is "mapped exclusively".

Example 1:

(1) App1 faults in a (shmem/file-backed) folio page -> Tracked as MM0
(2) App2 faults in a folio page -> Tracked as MM1
(4) App1 unmaps all folio pages

 -> We will detect "mapped exclusively".

Example 2:

(1) App1 faults in a (shmem/file-backed) folio page -> Tracked as MM0
(2) App2 faults in a folio page -> Tracked as MM1
(3) App3 faults in a folio page -> No slot available, tracked as "unknown"
(4) App1 and App2 unmap all folio pages

 -> We will detect "maybe mapped shared".

Make use of __always_inline to keep possible performance degradation when
(un)mapping large folios to a minimum.

Note: by squeezing the two flags into the "unsigned long" that stores the
MM ids, we can use non-atomic __bit_spin_unlock() and non-atomic
setting/clearing of the "maybe mapped shared" bit, effectively not adding
any new atomics on the hot path when updating the large mapcount + new
metadata, which further helps reduce the runtime overhead in
micro-benchmarks.

Link: https://lkml.kernel.org/r/20250303163014.1128035-13-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andy Lutomirks^H^Hski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Michal Koutn <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: tejun heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17 22:06:46 -07:00
Andrii Nakryiko
0c555a3c1b mm,procfs: allow read-only remote mm access under CAP_PERFMON
It's very common for various tracing and profiling toolis to need to
access /proc/PID/maps contents for stack symbolization needs to learn
which shared libraries are mapped in memory, at which file offset, etc. 
Currently, access to /proc/PID/maps requires CAP_SYS_PTRACE (unless we are
looking at data for our own process, which is a trivial case not too
relevant for profilers use cases).

Unfortunately, CAP_SYS_PTRACE implies way more than just ability to
discover memory layout of another process: it allows to fully control
arbitrary other processes.  This is problematic from security POV for
applications that only need read-only /proc/PID/maps (and other similar
read-only data) access, and in large production settings CAP_SYS_PTRACE is
frowned upon even for the system-wide profilers.

On the other hand, it's already possible to access similar kind of
information (and more) with just CAP_PERFMON capability.  E.g., setting up
PERF_RECORD_MMAP collection through perf_event_open() would give one
similar information to what /proc/PID/maps provides.

CAP_PERFMON, together with CAP_BPF, is already a very common combination
for system-wide profiling and observability application.  As such, it's
reasonable and convenient to be able to access /proc/PID/maps with
CAP_PERFMON capabilities instead of CAP_SYS_PTRACE.

For procfs, these permissions are checked through common mm_access()
helper, and so we augment that with cap_perfmon() check *only* if
requested mode is PTRACE_MODE_READ.  I.e., PTRACE_MODE_ATTACH wouldn't be
permitted by CAP_PERFMON.  So /proc/PID/mem, which uses
PTRACE_MODE_ATTACH, won't be permitted by CAP_PERFMON, but /proc/PID/maps,
/proc/PID/environ, and a bunch of other read-only contents will be
allowable under CAP_PERFMON.

Besides procfs itself, mm_access() is used by process_madvise() and
process_vm_{readv,writev}() syscalls.  The former one uses
PTRACE_MODE_READ to avoid leaking ASLR metadata, and as such CAP_PERFMON
seems like a meaningful allowable capability as well.

process_vm_{readv,writev} currently assume PTRACE_MODE_ATTACH level of
permissions (though for readv PTRACE_MODE_READ seems more reasonable, but
that's outside the scope of this change), and as such won't be affected by
this patch.

Link: https://lkml.kernel.org/r/20250127222114.1132392-1-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:46 -07:00
Suren Baghdasaryan
3104138517 mm: make vma cache SLAB_TYPESAFE_BY_RCU
To enable SLAB_TYPESAFE_BY_RCU for vma cache we need to ensure that
object reuse before RCU grace period is over will be detected by
lock_vma_under_rcu().

Current checks are sufficient as long as vma is detached before it is
freed.  The only place this is not currently happening is in exit_mmap(). 
Add the missing vma_mark_detached() in exit_mmap().

Another issue which might trick lock_vma_under_rcu() during vma reuse is
vm_area_dup(), which copies the entire content of the vma into a new one,
overriding new vma's vm_refcnt and temporarily making it appear as
attached.  This might trick a racing lock_vma_under_rcu() to operate on a
reused vma if it found the vma before it got reused.  To prevent this
situation, we should ensure that vm_refcnt stays at detached state (0)
when it is copied and advances to attached state only after it is added
into the vma tree.  Introduce vm_area_init_from() which preserves new
vma's vm_refcnt and use it in vm_area_dup().  Since all vmas are in
detached state with no current readers when they are freed,

lock_vma_under_rcu() will not be able to take vm_refcnt after vma got
detached even if vma is reused. vma_mark_attached() in modified to
include a release fence to ensure all stores to the vma happen before
vm_refcnt gets initialized.

Finally, make vm_area_cachep SLAB_TYPESAFE_BY_RCU. This will facilitate
vm_area_struct reuse and will minimize the number of call_rcu() calls.

[surenb@google.com: remove atomic_set_release() usage in tools/]
  Link: https://lkml.kernel.org/r/20250217054351.2973666-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250213224655.1680278-18-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:06:21 -07:00
Suren Baghdasaryan
f35ab95ca0 mm: replace vm_lock and detached flag with a reference count
rw_semaphore is a sizable structure of 40 bytes and consumes considerable
space for each vm_area_struct.  However vma_lock has two important
specifics which can be used to replace rw_semaphore with a simpler
structure:

1. Readers never wait.  They try to take the vma_lock and fall back to
   mmap_lock if that fails.

2. Only one writer at a time will ever try to write-lock a vma_lock
   because writers first take mmap_lock in write mode.  Because of these
   requirements, full rw_semaphore functionality is not needed and we can
   replace rw_semaphore and the vma->detached flag with a refcount
   (vm_refcnt).

When vma is in detached state, vm_refcnt is 0 and only a call to
vma_mark_attached() can take it out of this state.  Note that unlike
before, now we enforce both vma_mark_attached() and vma_mark_detached() to
be done only after vma has been write-locked.  vma_mark_attached() changes
vm_refcnt to 1 to indicate that it has been attached to the vma tree. 
When a reader takes read lock, it increments vm_refcnt, unless the top
usable bit of vm_refcnt (0x40000000) is set, indicating presence of a
writer.  When writer takes write lock, it sets the top usable bit to
indicate its presence.  If there are readers, writer will wait using newly
introduced mm->vma_writer_wait.  Since all writers take mmap_lock in write
mode first, there can be only one writer at a time.  The last reader to
release the lock will signal the writer to wake up.  refcount might
overflow if there are many competing readers, in which case read-locking
will fail.  Readers are expected to handle such failures.

In summary:
1. all readers increment the vm_refcnt;
2. writer sets top usable (writer) bit of vm_refcnt;
3. readers cannot increment the vm_refcnt if the writer bit is set;
4. in the presence of readers, writer must wait for the vm_refcnt to drop
to 1 (plus the VMA_LOCK_OFFSET writer bit), indicating an attached vma
with no readers;
5. vm_refcnt overflow is handled by the readers.

While this vm_lock replacement does not yet result in a smaller
vm_area_struct (it stays at 256 bytes due to cacheline alignment), it
allows for further size optimization by structure member regrouping to
bring the size of vm_area_struct below 192 bytes.

[surenb@google.com: fix a crash due to vma_end_read() that should have been removed]
  Link: https://lkml.kernel.org/r/20250220200208.323769-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250213224655.1680278-13-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:06:20 -07:00
Suren Baghdasaryan
ce08539660 mm: move mmap_init_lock() out of the header file
mmap_init_lock() is used only from mm_init() in fork.c, therefore it does
not have to reside in the header file.  This move lets us avoid including
additional headers in mmap_lock.h later, when mmap_init_lock() needs to
initialize rcuwait object.

Link: https://lkml.kernel.org/r/20250213224655.1680278-9-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:06:19 -07:00
Suren Baghdasaryan
8ef95d8f15 mm: mark vma as detached until it's added into vma tree
Current implementation does not set detached flag when a VMA is first
allocated.  This does not represent the real state of the VMA, which is
detached until it is added into mm's VMA tree.  Fix this by marking new
VMAs as detached and resetting detached flag only after VMA is added into
a tree.

Introduce vma_mark_attached() to make the API more readable and to
simplify possible future cleanup when vma->vm_mm might be used to indicate
detached vma and vma_mark_attached() will need an additional mm parameter.

Link: https://lkml.kernel.org/r/20250213224655.1680278-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:06:17 -07:00
Suren Baghdasaryan
7b6218ae12 mm: move per-vma lock into vm_area_struct
Back when per-vma locks were introduces, vm_lock was moved out of
vm_area_struct in [1] because of the performance regression caused by
false cacheline sharing.  Recent investigation [2] revealed that the
regressions is limited to a rather old Broadwell microarchitecture and
even there it can be mitigated by disabling adjacent cacheline
prefetching, see [3].

Splitting single logical structure into multiple ones leads to more
complicated management, extra pointer dereferences and overall less
maintainable code.  When that split-away part is a lock, it complicates
things even further.  With no performance benefits, there are no reasons
for this split.  Merging the vm_lock back into vm_area_struct also allows
vm_area_struct to use SLAB_TYPESAFE_BY_RCU later in this patchset.  Move
vm_lock back into vm_area_struct, aligning it at the cacheline boundary
and changing the cache to be cacheline-aligned as well.  With kernel
compiled using defconfig, this causes VMA memory consumption to grow from
160 (vm_area_struct) + 40 (vm_lock) bytes to 256 bytes:

    slabinfo before:
     <name>           ... <objsize> <objperslab> <pagesperslab> : ...
     vma_lock         ...     40  102    1 : ...
     vm_area_struct   ...    160   51    2 : ...

    slabinfo after moving vm_lock:
     <name>           ... <objsize> <objperslab> <pagesperslab> : ...
     vm_area_struct   ...    256   32    2 : ...

Aggregate VMA memory consumption per 1000 VMAs grows from 50 to 64 pages,
which is 5.5MB per 100000 VMAs.  Note that the size of this structure is
dependent on the kernel configuration and typically the original size is
higher than 160 bytes.  Therefore these calculations are close to the
worst case scenario.  A more realistic vm_area_struct usage before this
change is:

     <name>           ... <objsize> <objperslab> <pagesperslab> : ...
     vma_lock         ...     40  102    1 : ...
     vm_area_struct   ...    176   46    2 : ...

Aggregate VMA memory consumption per 1000 VMAs grows from 54 to 64 pages,
which is 3.9MB per 100000 VMAs.  This memory consumption growth can be
addressed later by optimizing the vm_lock.

[1] https://lore.kernel.org/all/20230227173632.3292573-34-surenb@google.com/
[2] https://lore.kernel.org/all/ZsQyI%2F087V34JoIt@xsang-OptiPlex-9020/
[3] https://lore.kernel.org/all/CAJuCfpEisU8Lfe96AYJDZ+OM4NoPmnw9bP53cT_kbfP_pR+-2g@mail.gmail.com/

Link: https://lkml.kernel.org/r/20250213224655.1680278-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:06:17 -07:00
Christian Brauner
3155a19407
pidfs: move setting flags into pidfs_alloc_file()
Instead od adding it into __pidfd_prepare() place it where the actual
file allocation happens and update the outdated comment.

Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-3-c8c3d8361705@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-03-05 13:26:05 +01:00