Locking primitives:
- Mark devm_mutex_init() as __must_check and fix drivers
that didn't check the return code. (Thomas Weißschuh)
- Reorganize <linux/local_lock.h> to better expose the
internal APIs to local variables. (Sebastian Andrzej Siewior)
- Remove OWNER_SPINNABLE in rwsem (Jinliang Zheng)
- Remove redundant #ifdefs in the mutex code (Ran Xiaokai)
Lockdep:
- Avoid returning struct in lock_stats() (Arnd Bergmann)
- Change `static const` into enum for LOCKF_*_IRQ_*
(Arnd Bergmann)
- Temporarily use synchronize_rcu_expedited() in
lockdep_unregister_key() to speed things up.
(Breno Leitao)
Rust runtime:
- Add #[must_use] to Lock::try_lock() (Jason Devers)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"Locking primitives:
- Mark devm_mutex_init() as __must_check and fix drivers that didn't
check the return code (Thomas Weißschuh)
- Reorganize <linux/local_lock.h> to better expose the internal APIs
to local variables (Sebastian Andrzej Siewior)
- Remove OWNER_SPINNABLE in rwsem (Jinliang Zheng)
- Remove redundant #ifdefs in the mutex code (Ran Xiaokai)
Lockdep:
- Avoid returning struct in lock_stats() (Arnd Bergmann)
- Change `static const` into enum for LOCKF_*_IRQ_* (Arnd Bergmann)
- Temporarily use synchronize_rcu_expedited() in
lockdep_unregister_key() to speed things up. (Breno Leitao)
Rust runtime:
- Add #[must_use] to Lock::try_lock() (Jason Devers)"
* tag 'locking-core-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
lockdep: Speed up lockdep_unregister_key() with expedited RCU synchronization
locking/mutex: Remove redundant #ifdefs
locking/lockdep: Change 'static const' variables to enum values
locking/lockdep: Avoid struct return in lock_stats()
locking/rwsem: Use OWNER_NONSPINNABLE directly instead of OWNER_SPINNABLE
rust: sync: Add #[must_use] to Lock::try_lock()
locking/mutex: Mark devm_mutex_init() as __must_check
leds: lp8860: Check return value of devm_mutex_init()
spi: spi-nxp-fspi: Check return value of devm_mutex_init()
local_lock: Move this_cpu_ptr() notation from internal to main header
hung_task_{set,clear}_blocker() is already guarded by
CONFIG_DETECT_HUNG_TASK_BLOCKER in hung_task.h, So remove
the redudant check of #ifdef.
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250704015218.359754-1-ranxiaokai627@163.com
This lets us assert mutex::wait_lock is held whenever we access
p->blocked_on, as well as warn us for unexpected state changes.
[fix conflicts, call in more places]
[jstultz: tweaked commit subject, reworked a good bit]
Signed-off-by: Valentin Schneider <valentin.schneider@arm.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/20250712033407.2383110-4-jstultz@google.com
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
* Clean up locking of all vCPUs for a VM by using the *_nest_lock()
family of functions, and move duplicated code to virt/kvm/.
kernel/ patches acked by Peter Zijlstra.
* Add MGLRU support to the access tracking perf test.
ARM fixes:
* Make the irqbypass hooks resilient to changes in the GSI<->MSI
routing, avoiding behind stale vLPI mappings being left behind. The
fix is to resolve the VGIC IRQ using the host IRQ (which is stable)
and nuking the vLPI mapping upon a routing change.
* Close another VGIC race where vCPU creation races with VGIC
creation, leading to in-flight vCPUs entering the kernel w/o private
IRQs allocated.
* Fix a build issue triggered by the recently added workaround for
Ampere's AC04_CPU_23 erratum.
* Correctly sign-extend the VA when emulating a TLBI instruction
potentially targeting a VNCR mapping.
* Avoid dereferencing a NULL pointer in the VGIC debug code, which can
happen if the device doesn't have any mapping yet.
s390:
* Fix interaction between some filesystems and Secure Execution
* Some cleanups and refactorings, preparing for an upcoming big series
x86:
* Wait for target vCPU to acknowledge KVM_REQ_UPDATE_PROTECTED_GUEST_STATE to
fix a race between AP destroy and VMRUN.
* Decrypt and dump the VMSA in dump_vmcb() if debugging enabled for the VM.
* Refine and harden handling of spurious faults.
* Add support for ALLOWED_SEV_FEATURES.
* Add #VMGEXIT to the set of handlers special cased for CONFIG_RETPOLINE=y.
* Treat DEBUGCTL[5:2] as reserved to pave the way for virtualizing features
that utilize those bits.
* Don't account temporary allocations in sev_send_update_data().
* Add support for KVM_CAP_X86_BUS_LOCK_EXIT on SVM, via Bus Lock Threshold.
* Unify virtualization of IBRS on nested VM-Exit, and cross-vCPU IBPB, between
SVM and VMX.
* Advertise support to userspace for WRMSRNS and PREFETCHI.
* Rescan I/O APIC routes after handling EOI that needed to be intercepted due
to the old/previous routing, but not the new/current routing.
* Add a module param to control and enumerate support for device posted
interrupts.
* Fix a potential overflow with nested virt on Intel systems running 32-bit kernels.
* Flush shadow VMCSes on emergency reboot.
* Add support for SNP to the various SEV selftests.
* Add a selftest to verify fastops instructions via forced emulation.
* Refine and optimize KVM's software processing of the posted interrupt bitmap, and share
the harvesting code between KVM and the kernel's Posted MSI handler
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull more kvm updates from Paolo Bonzini:
Generic:
- Clean up locking of all vCPUs for a VM by using the *_nest_lock()
family of functions, and move duplicated code to virt/kvm/. kernel/
patches acked by Peter Zijlstra
- Add MGLRU support to the access tracking perf test
ARM fixes:
- Make the irqbypass hooks resilient to changes in the GSI<->MSI
routing, avoiding behind stale vLPI mappings being left behind. The
fix is to resolve the VGIC IRQ using the host IRQ (which is stable)
and nuking the vLPI mapping upon a routing change
- Close another VGIC race where vCPU creation races with VGIC
creation, leading to in-flight vCPUs entering the kernel w/o
private IRQs allocated
- Fix a build issue triggered by the recently added workaround for
Ampere's AC04_CPU_23 erratum
- Correctly sign-extend the VA when emulating a TLBI instruction
potentially targeting a VNCR mapping
- Avoid dereferencing a NULL pointer in the VGIC debug code, which
can happen if the device doesn't have any mapping yet
s390:
- Fix interaction between some filesystems and Secure Execution
- Some cleanups and refactorings, preparing for an upcoming big
series
x86:
- Wait for target vCPU to ack KVM_REQ_UPDATE_PROTECTED_GUEST_STATE
to fix a race between AP destroy and VMRUN
- Decrypt and dump the VMSA in dump_vmcb() if debugging enabled for
the VM
- Refine and harden handling of spurious faults
- Add support for ALLOWED_SEV_FEATURES
- Add #VMGEXIT to the set of handlers special cased for
CONFIG_RETPOLINE=y
- Treat DEBUGCTL[5:2] as reserved to pave the way for virtualizing
features that utilize those bits
- Don't account temporary allocations in sev_send_update_data()
- Add support for KVM_CAP_X86_BUS_LOCK_EXIT on SVM, via Bus Lock
Threshold
- Unify virtualization of IBRS on nested VM-Exit, and cross-vCPU
IBPB, between SVM and VMX
- Advertise support to userspace for WRMSRNS and PREFETCHI
- Rescan I/O APIC routes after handling EOI that needed to be
intercepted due to the old/previous routing, but not the
new/current routing
- Add a module param to control and enumerate support for device
posted interrupts
- Fix a potential overflow with nested virt on Intel systems running
32-bit kernels
- Flush shadow VMCSes on emergency reboot
- Add support for SNP to the various SEV selftests
- Add a selftest to verify fastops instructions via forced emulation
- Refine and optimize KVM's software processing of the posted
interrupt bitmap, and share the harvesting code between KVM and the
kernel's Posted MSI handler"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (93 commits)
rtmutex_api: provide correct extern functions
KVM: arm64: vgic-debug: Avoid dereferencing NULL ITE pointer
KVM: arm64: vgic-init: Plug vCPU vs. VGIC creation race
KVM: arm64: Unmap vLPIs affected by changes to GSI routing information
KVM: arm64: Resolve vLPI by host IRQ in vgic_v4_unset_forwarding()
KVM: arm64: Protect vLPI translation with vgic_irq::irq_lock
KVM: arm64: Use lock guard in vgic_v4_set_forwarding()
KVM: arm64: Mask out non-VA bits from TLBI VA* on VNCR invalidation
arm64: sysreg: Drag linux/kconfig.h to work around vdso build issue
KVM: s390: Simplify and move pv code
KVM: s390: Refactor and split some gmap helpers
KVM: s390: Remove unneeded srcu lock
s390: Remove unneeded includes
s390/uv: Improve splitting of large folios that cannot be split while dirty
s390/uv: Always return 0 from s390_wiggle_split_folio() if successful
s390/uv: Don't return 0 from make_hva_secure() if the operation was not successful
rust: add helper for mutex_trylock
RISC-V: KVM: use kvm_trylock_all_vcpus when locking all vCPUs
KVM: arm64: use kvm_trylock_all_vcpus when locking all vCPUs
x86: KVM: SVM: use kvm_lock_all_vcpus instead of a custom implementation
...
KVM's SEV intra-host migration code needs to lock all vCPUs
of the source and the target VM, before it proceeds with the migration.
The number of vCPUs that belong to each VM is not bounded by anything
except a self-imposed KVM limit of CONFIG_KVM_MAX_NR_VCPUS vCPUs which is
significantly larger than the depth of lockdep's lock stack.
Luckily, the locks in both of the cases mentioned above, are held under
the 'kvm->lock' of each VM, which means that we can use the little
known lockdep feature called a "nest_lock" to support this use case in
a cleaner way, compared to the way it's currently done.
Implement and expose 'mutex_lock_killable_nest_lock' for this
purpose.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-ID: <20250512180407.659015-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Despite the fact that several lockdep-related checks are skipped when
calling trylock* versions of the locking primitives, for example
mutex_trylock, each time the mutex is acquired, a held_lock is still
placed onto the lockdep stack by __lock_acquire() which is called
regardless of whether the trylock* or regular locking API was used.
This means that if the caller successfully acquires more than
MAX_LOCK_DEPTH locks of the same class, even when using mutex_trylock,
lockdep will still complain that the maximum depth of the held lock stack
has been reached and disable itself.
For example, the following error currently occurs in the ARM version
of KVM, once the code tries to lock all vCPUs of a VM configured with more
than MAX_LOCK_DEPTH vCPUs, a situation that can easily happen on modern
systems, where having more than 48 CPUs is common, and it's also common to
run VMs that have vCPU counts approaching that number:
[ 328.171264] BUG: MAX_LOCK_DEPTH too low!
[ 328.175227] turning off the locking correctness validator.
[ 328.180726] Please attach the output of /proc/lock_stat to the bug report
[ 328.187531] depth: 48 max: 48!
[ 328.190678] 48 locks held by qemu-kvm/11664:
[ 328.194957] #0: ffff800086de5ba0 (&kvm->lock){+.+.}-{3:3}, at: kvm_ioctl_create_device+0x174/0x5b0
[ 328.204048] #1: ffff0800e78800b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[ 328.212521] #2: ffff07ffeee51e98 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[ 328.220991] #3: ffff0800dc7d80b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[ 328.229463] #4: ffff07ffe0c980b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[ 328.237934] #5: ffff0800a3883c78 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[ 328.246405] #6: ffff07fffbe480b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
Luckily, in all instances that require locking all vCPUs, the
'kvm->lock' is taken a priori, and that fact makes it possible to use
the little known feature of lockdep, called a 'nest_lock', to avoid this
warning and subsequent lockdep self-disablement.
The action of 'nested lock' being provided to lockdep's lock_acquire(),
causes the lockdep to detect that the top of the held lock stack contains
a lock of the same class and then increment its reference counter instead
of pushing a new held_lock item onto that stack.
See __lock_acquire for more information.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-ID: <20250512180407.659015-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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
...
Patch series "hung_task: Dump the blocking task stacktrace", v4.
The hung_task detector is very useful for detecting the lockup. However,
since it only dumps the blocked (uninterruptible sleep) processes, it is
not enough to identify the root cause of that lockup.
For example, if a process holds a mutex and sleep an event in
interruptible state long time, the other processes will wait on the mutex
in uninterruptible state. In this case, the waiter processes are dumped,
but the blocker process is not shown because it is sleep in interruptible
state.
This adds a feature to dump the blocker task which holds a mutex
when detecting a hung task. e.g.
INFO: task cat:115 blocked for more than 122 seconds.
Not tainted 6.14.0-rc3-00003-ga8946be3de00 #156
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:cat state:D stack:13432 pid:115 tgid:115 ppid:106 task_flags:0x400100 flags:0x00000002
Call Trace:
<TASK>
__schedule+0x731/0x960
? schedule_preempt_disabled+0x54/0xa0
schedule+0xb7/0x140
? __mutex_lock+0x51b/0xa60
? __mutex_lock+0x51b/0xa60
schedule_preempt_disabled+0x54/0xa0
__mutex_lock+0x51b/0xa60
read_dummy+0x23/0x70
full_proxy_read+0x6a/0xc0
vfs_read+0xc2/0x340
? __pfx_direct_file_splice_eof+0x10/0x10
? do_sendfile+0x1bd/0x2e0
ksys_read+0x76/0xe0
do_syscall_64+0xe3/0x1c0
? exc_page_fault+0xa9/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x4840cd
RSP: 002b:00007ffe99071828 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004840cd
RDX: 0000000000001000 RSI: 00007ffe99071870 RDI: 0000000000000003
RBP: 00007ffe99071870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000
R13: 00000000132fd3a0 R14: 0000000000000001 R15: ffffffffffffffff
</TASK>
INFO: task cat:115 is blocked on a mutex likely owned by task cat:114.
task:cat state:S stack:13432 pid:114 tgid:114 ppid:106 task_flags:0x400100 flags:0x00000002
Call Trace:
<TASK>
__schedule+0x731/0x960
? schedule_timeout+0xa8/0x120
schedule+0xb7/0x140
schedule_timeout+0xa8/0x120
? __pfx_process_timeout+0x10/0x10
msleep_interruptible+0x3e/0x60
read_dummy+0x2d/0x70
full_proxy_read+0x6a/0xc0
vfs_read+0xc2/0x340
? __pfx_direct_file_splice_eof+0x10/0x10
? do_sendfile+0x1bd/0x2e0
ksys_read+0x76/0xe0
do_syscall_64+0xe3/0x1c0
? exc_page_fault+0xa9/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x4840cd
RSP: 002b:00007ffe3e0147b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004840cd
RDX: 0000000000001000 RSI: 00007ffe3e014800 RDI: 0000000000000003
RBP: 00007ffe3e014800 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000
R13: 000000001a0a93a0 R14: 0000000000000001 R15: ffffffffffffffff
</TASK>
TBD: We can extend this feature to cover other locks like rwsem and
rt_mutex, but rwsem requires to dump all the tasks which acquire and wait
that rwsem. We can follow the waiter link but the output will be a bit
different compared with mutex case.
This patch (of 2):
The "hung_task" shows a long-time uninterruptible slept task, but most
often, it's blocked on a mutex acquired by another task. Without dumping
such a task, investigating the root cause of the hung task problem is very
difficult.
This introduce task_struct::blocker_mutex to point the mutex lock which
this task is waiting for. Since the mutex has "owner" information, we can
find the owner task and dump it with hung tasks.
Note: the owner can be changed while dumping the owner task, so
this is "likely" the owner of the mutex.
With this change, the hung task shows blocker task's info like below;
INFO: task cat:115 blocked for more than 122 seconds.
Not tainted 6.14.0-rc3-00003-ga8946be3de00 #156
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:cat state:D stack:13432 pid:115 tgid:115 ppid:106 task_flags:0x400100 flags:0x00000002
Call Trace:
<TASK>
__schedule+0x731/0x960
? schedule_preempt_disabled+0x54/0xa0
schedule+0xb7/0x140
? __mutex_lock+0x51b/0xa60
? __mutex_lock+0x51b/0xa60
schedule_preempt_disabled+0x54/0xa0
__mutex_lock+0x51b/0xa60
read_dummy+0x23/0x70
full_proxy_read+0x6a/0xc0
vfs_read+0xc2/0x340
? __pfx_direct_file_splice_eof+0x10/0x10
? do_sendfile+0x1bd/0x2e0
ksys_read+0x76/0xe0
do_syscall_64+0xe3/0x1c0
? exc_page_fault+0xa9/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x4840cd
RSP: 002b:00007ffe99071828 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004840cd
RDX: 0000000000001000 RSI: 00007ffe99071870 RDI: 0000000000000003
RBP: 00007ffe99071870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000
R13: 00000000132fd3a0 R14: 0000000000000001 R15: ffffffffffffffff
</TASK>
INFO: task cat:115 is blocked on a mutex likely owned by task cat:114.
task:cat state:S stack:13432 pid:114 tgid:114 ppid:106 task_flags:0x400100 flags:0x00000002
Call Trace:
<TASK>
__schedule+0x731/0x960
? schedule_timeout+0xa8/0x120
schedule+0xb7/0x140
schedule_timeout+0xa8/0x120
? __pfx_process_timeout+0x10/0x10
msleep_interruptible+0x3e/0x60
read_dummy+0x2d/0x70
full_proxy_read+0x6a/0xc0
vfs_read+0xc2/0x340
? __pfx_direct_file_splice_eof+0x10/0x10
? do_sendfile+0x1bd/0x2e0
ksys_read+0x76/0xe0
do_syscall_64+0xe3/0x1c0
? exc_page_fault+0xa9/0x1d0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x4840cd
RSP: 002b:00007ffe3e0147b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004840cd
RDX: 0000000000001000 RSI: 00007ffe3e014800 RDI: 0000000000000003
RBP: 00007ffe3e014800 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000
R13: 000000001a0a93a0 R14: 0000000000000001 R15: ffffffffffffffff
</TASK>
[akpm@linux-foundation.org: implement debug_show_blocker() in C rather than in CPP]
Link: https://lkml.kernel.org/r/174046694331.2194069.15472952050240807469.stgit@mhiramat.tok.corp.google.com
Link: https://lkml.kernel.org/r/174046695384.2194069.16796289525958195643.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Will Deacon <will@kernel.org>
Cc: Yongliang Gao <leonylgao@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Scenario: In platform_device_register, the driver misuses struct
device as platform_data, making kmemdup duplicate a device. Accessing
the duplicate may cause list corruption due to its mutex magic or list
holding old content.
It recurs randomly as the first mutex - getting process skips the slow
path and mutex check. Adding MUTEX_WARN_ON(lock->magic!= lock) in
__mutex_trylock_fast() makes it always happen.
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250126033243.53069-1-cuiyunhui@bytedance.com
A common pattern seen when wake_qs are used to defer a wakeup
until after a lock is released is something like:
preempt_disable();
raw_spin_unlock(lock);
wake_up_q(wake_q);
preempt_enable();
So create some raw_spin_unlock*_wake() helper functions to clean
this up.
Applies on top of the fix I submitted here:
https://lore.kernel.org/lkml/20241212222138.2400498-1-jstultz@google.com/
NOTE: I recognise the unlock()/unlock_irq()/unlock_irqrestore()
variants creates its own duplication, which we could use a macro
to generate the similar functions, but I often dislike how those
generation macros making finding the actual implementation
harder, so I left the three functions as is. If folks would
prefer otherwise, let me know and I'll switch it.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241217040803.243420-1-jstultz@google.com
Implementing proxy execution requires that scheduler code be able to
identify the current owner of a mutex. Expose __mutex_owner() for
this purpose (alone!). Includes a null mutex check, so that users
of the function can be simplified.
[Removed the EXPORT_SYMBOL]
[jstultz: Reworked per Peter's suggestions]
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.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>
Reviewed-by: Metin Kaya <metin.kaya@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Metin Kaya <metin.kaya@arm.com>
Link: https://lore.kernel.org/r/20241009235352.1614323-4-jstultz@google.com
With the proxy-execution series, we traverse the task->mutex->task
blocked_on/owner chain in the scheduler core. We do this while holding
the rq::lock to keep the structures in place while taking and
releasing the alternating lock types.
Since the mutex::wait_lock is one of the locks we will take in this
way under the rq::lock in the scheduler core, we need to make sure
that its usage elsewhere is irq safe.
[rebase & fix {un,}lock_wait_lock helpers in ww_mutex.h]
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>
Reviewed-by: Metin Kaya <metin.kaya@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Metin Kaya <metin.kaya@arm.com>
Link: https://lore.kernel.org/r/20241009235352.1614323-3-jstultz@google.com
In preparation to nest mutex::wait_lock under rq::lock we need
to remove wakeups from under it.
Do this by utilizing wake_qs to defer the wakeup until after the
lock is dropped.
[Heavily changed after 55f036ca7e ("locking: WW mutex cleanup") and
08295b3b5b ("locking: Implement an algorithm choice for Wound-Wait
mutexes")]
[jstultz: rebased to mainline, added extra wake_up_q & init
to avoid hangs, similar to Connor's rework of this patch]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Metin Kaya <metin.kaya@arm.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Metin Kaya <metin.kaya@arm.com>
Link: https://lore.kernel.org/r/20241009235352.1614323-2-jstultz@google.com
I have seen several cases of attempts to use mutex_unlock() to release an
object such that the object can then be freed by another task.
This is not safe because mutex_unlock(), in the
MUTEX_FLAG_WAITERS && !MUTEX_FLAG_HANDOFF case, accesses the mutex
structure after having marked it as unlocked; so mutex_unlock() requires
its caller to ensure that the mutex stays alive until mutex_unlock()
returns.
If MUTEX_FLAG_WAITERS is set and there are real waiters, those waiters
have to keep the mutex alive, but we could have a spurious
MUTEX_FLAG_WAITERS left if an interruptible/killable waiter bailed
between the points where __mutex_unlock_slowpath() did the cmpxchg
reading the flags and where it acquired the wait_lock.
( With spinlocks, that kind of code pattern is allowed and, from what I
remember, used in several places in the kernel. )
Document this, such a semantic difference between mutexes and spinlocks
is fairly unintuitive.
[ mingo: Made the changelog a bit more assertive, refined the comments. ]
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231130204817.2031407-1-jannh@google.com
The bcachefs implementation of six locks is intended to land in
generic locking code in the long term, but has been pulled into the
bcachefs subsystem for internal use for the time being. This code
lift breaks the bcachefs module build as six locks depend a couple
of the generic locking tracepoints. Export these tracepoint symbols
for bcachefs.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Have the trace_contention_*() tracepoints consistently include
adaptive spinning. In order to differentiate between the spinning and
non-spinning states add LCB_F_MUTEX and combine with LCB_F_SPIN.
The consequence is that a mutex contention can now triggler multiple
_begin() tracepoints before triggering an _end().
Additionally, this fixes one path where mutex would trigger _end()
without ever seeing a _begin().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Adding the lock contention tracepoints in various lock function slow
paths. Note that each arch can define spinlock differently, I only
added it only to the generic qspinlock for now.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Link: https://lkml.kernel.org/r/20220322185709.141236-3-namhyung@kernel.org
This adds two new lock contention tracepoints like below:
* lock:contention_begin
* lock:contention_end
The lock:contention_begin takes a flags argument to classify locks. I
found it useful to identify what kind of locks it's tracing like if
it's spinning or sleeping, reader-writer lock, real-time, and per-cpu.
Move tracepoint definitions into mutex.c so that we can use them
without lockdep.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Link: https://lkml.kernel.org/r/20220322185709.141236-2-namhyung@kernel.org
Move the owner_on_cpu() from kernel/locking/rwsem.c into
include/linux/sched.h with under CONFIG_SMP, then use it
in the mutex/rwsem/rtmutex to simplify the code.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211203075935.136808-2-wangkefeng.wang@huawei.com
preempt_disable/enable() is equal to RCU read-side crital section, and
the spinning codes in mutex and rwsem could ensure that the preemption
is disabled. So let's remove the unnecessary rcu_read_lock/unlock for
saving some cycles in hot codes.
Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20211013134154.1085649-2-yanfei.xu@windriver.com
i915 will soon gain an eviction path that trylock a whole lot of locks
for eviction, getting dmesg failures like below:
BUG: MAX_LOCK_DEPTH too low!
turning off the locking correctness validator.
depth: 48 max: 48!
48 locks held by i915_selftest/5776:
#0: ffff888101a79240 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x88/0x160
#1: ffffc900009778c0 (reservation_ww_class_acquire){+.+.}-{0:0}, at: i915_vma_pin.constprop.63+0x39/0x1b0 [i915]
#2: ffff88800cf74de8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_vma_pin.constprop.63+0x5f/0x1b0 [i915]
#3: ffff88810c7f9e38 (&vm->mutex/1){+.+.}-{3:3}, at: i915_vma_pin_ww+0x1c4/0x9d0 [i915]
#4: ffff88810bad5768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
#5: ffff88810bad60e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
...
#46: ffff88811964d768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
#47: ffff88811964e0e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915]
INFO: lockdep is turned off.
Fixing eviction to nest into ww_class_acquire is a high priority, but
it requires a rework of the entire driver, which can only be done one
step at a time.
As an intermediate solution, add an acquire context to
ww_mutex_trylock, which allows us to do proper nesting annotations on
the trylocks, making the above lockdep splat disappear.
This is also useful in regulator_lock_nested, which may avoid dropping
regulator_nesting_mutex in the uncontended path, so use it there.
TTM may be another user for this, where we could lock a buffer in a
fastpath with list locks held, without dropping all locks we hold.
[peterz: rework actual ww_mutex_trylock() implementations]
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YUBGPdDDjKlxAuXJ@hirez.programming.kicks-ass.net
The consolidation of the debug code for mutex waiter intialization sets
waiter::ww_ctx to a poison value unconditionally. For regular mutexes this
is intended to catch the case where waiter_ww_ctx is dereferenced
accidentally.
For ww_mutex the poison value has to be overwritten either with a context
pointer or NULL for ww_mutexes without context.
The rework broke this as it made the store conditional on the context
pointer instead of the argument which signals whether ww_mutex code should
be compiled in or optiized out. As a result waiter::ww_ctx ends up with the
poison pointer for contextless ww_mutexes which causes a later dereference of
the poison pointer because it is != NULL.
Use the build argument instead so for ww_mutex the poison value is always
overwritten.
Fixes: c0afb0ffc0 ("locking/ww_mutex: Gather mutex_waiter initialization")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210819193030.zpwrpvvrmy7xxxiy@linutronix.de
Add the necessary defines, helpers and API functions for replacing struct mutex on
a PREEMPT_RT enabled kernel with an rtmutex based variant.
No functional change when CONFIG_PREEMPT_RT=n
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.081517417@linutronix.de
Split the W/W mutex helper functions out into a separate header file, so
they can be shared with a rtmutex based variant later.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211304.396893399@linutronix.de
Split the ww related part out into a helper function so it can be reused
for a rtmutex based ww_mutex implementation.
[ mingo: Fixed bisection failure. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211304.340166556@linutronix.de
The wait_lock of mutex is really a low level lock. Convert it to a
raw_spinlock like the wait_lock of rtmutex.
[ mingo: backmerged the test_lockup.c build fix by bigeasy. ]
Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211304.166863404@linutronix.de
Having two header files which contain just the non-debug and debug variants
is mostly waste of disc space and has no real value. Stick the debug
variants into the common mutex.h file as counterpart to the stubs for the
non-debug case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211303.995350521@linutronix.de
Yanfei reported that it is possible to loose HANDOFF when we race with
mutex_unlock() and end up setting HANDOFF on an unlocked mutex. At
that point anybody can steal it, losing HANDOFF in the process.
If this happens often enough, we can in fact starve the top waiter.
Solve this by folding the 'set HANDOFF' operation into the trylock
operation, such that either we acquire the lock, or it gets HANDOFF
set. This avoids having HANDOFF set on an unlocked mutex.
Reported-by: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Yanfei Xu <yanfei.xu@windriver.com>
Link: https://lore.kernel.org/r/20210630154114.958507900@infradead.org
Yanfei reported that setting HANDOFF should not depend on recomputing
@first, only on @first state. Which would then give:
if (ww_ctx || !first)
first = __mutex_waiter_is_first(lock, &waiter);
if (first)
__mutex_set_flag(lock, MUTEX_FLAG_HANDOFF);
But because 'ww_ctx || !first' is basically 'always' and the test for
first is relatively cheap, omit that first branch entirely.
Reported-by: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Yanfei Xu <yanfei.xu@windriver.com>
Link: https://lore.kernel.org/r/20210630154114.896786297@infradead.org
Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
When a interruptible mutex locker is interrupted by a signal
without acquiring this lock and removed from the wait queue.
if the mutex isn't contended enough to have a waiter
put into the wait queue again, the setting of the WAITER
bit will force mutex locker to go into the slowpath to
acquire the lock every time, so if the wait queue is empty,
the WAITER bit need to be clear.
Fixes: 040a0a3710 ("mutex: Add support for wound/wait style locks")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210517034005.30828-1-qiang.zhang@windriver.com
The use_ww_ctx flag is passed to mutex_optimistic_spin(), but the
function doesn't use it. The frequent use of the (use_ww_ctx && ww_ctx)
combination is repetitive.
In fact, ww_ctx should not be used at all if !use_ww_ctx. Simplify
ww_mutex code by dropping use_ww_ctx from mutex_optimistic_spin() an
clear ww_ctx if !use_ww_ctx. In this way, we can replace (use_ww_ctx &&
ww_ctx) by just (ww_ctx).
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Link: https://lore.kernel.org/r/20210316153119.13802-2-longman@redhat.com
There are not users of mutex_trylock_recursive() in tree as of
v5.11-rc7.
Remove it.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210210085248.219210-2-bigeasy@linutronix.de
This ended up causing some noise in places such as rxrpc running in softirq.
The warning is misleading in this case as the mutex trylock and unlock
operations are done within the same context; and therefore we need not
worry about the PI-boosting issues that comes along with no single-owner
lock guarantees.
While we don't want to support this in mutexes, there is no way out of
this yet; so lets get rid of the WARNs for now, as it is only fair to
code that has historically relied on non-preemptible softirq guarantees.
In addition, changing the lock type is also unviable: exclusive rwsems
have the same issue (just not the WARN_ON) and counting semaphores
would introduce a performance hit as mutexes are a lot more optimized.
This reverts:
a0855d24fc: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
Fixes: a0855d24fc: ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Tested-by: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-afs@lists.infradead.org
Cc: linux-fsdevel@vger.kernel.org
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/20191210220523.28540-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add warning checks if mutex_trylock() or mutex_unlock() are used in
IRQ contexts, under CONFIG_DEBUG_MUTEXES=y.
While the mutex rules and semantics are explicitly documented, this allows
to expose any abusers and robustifies the whole thing.
While trylock and unlock are non-blocking, calling from IRQ context
is still forbidden (lock must be within the same context as unlock).
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Link: https://lkml.kernel.org/r/20191025033634.3330-1-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The patch moving bits into mutex.c was a little too much; by also
moving struct mutex_waiter a few less common CONFIGs would no longer
build.
Fixes: 5f35d5a66b ("locking/mutex: Make __mutex_owner static to mutex.c")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
__mutex_owner() should only be used by the mutex api's.
So, to put this restiction let's move the __mutex_owner()
function definition from linux/mutex.h to mutex.c file.
There exist functions that uses __mutex_owner() like
mutex_is_locked() and mutex_trylock_recursive(), So
to keep legacy thing intact move them as well and
export them.
Move mutex_waiter structure also to keep it private to the
file.
Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mingo@redhat.com
Cc: will@kernel.org
Link: https://lkml.kernel.org/r/1564585504-3543-1-git-send-email-mojha@codeaurora.org
An uninitialized/ zeroed mutex will go unnoticed because there is no
check for it. There is a magic check in the unlock's slowpath path which
might go unnoticed if the unlock happens in the fastpath.
Add a ->magic check early in the mutex_lock() and mutex_trylock() path.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190703092125.lsdf4gpsh2plhavb@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Convert the locking documents to ReST and add them to the
kernel development book where it belongs.
Most of the stuff here is just to make Sphinx to properly
parse the text file, as they're already in good shape,
not requiring massive changes in order to be parsed.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Federico Vaga <federico.vaga@vaga.pv.it>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
