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8047212: runtime/ParallelClassLoading/bootstrap/random/inner-complex assert(ObjectSynchronizer::verify_objmon_isinpool(inf)) failed: monitor is invalid

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Fix race between ObjectMonitor alloc and verification code; teach SA about "static pointer volatile" fields.

Reviewed-by: cvarming, dholmes, sspitsyn, coleenp
This commit is contained in:
Daniel D. Daugherty 2015-10-24 15:44:08 -07:00
parent ed82cd0ee8
commit cb0500e51d
3 changed files with 70 additions and 50 deletions
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99
hotspot/src/share/vm/runtime/synchronizer.cpp
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@ -116,7 +116,7 @@ static volatile intptr_t gInflationLocks[NINFLATIONLOCKS];
// global list of blocks of monitors
// gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't
// want to expose the PaddedEnd template more than necessary.
ObjectMonitor * ObjectSynchronizer::gBlockList = NULL;
ObjectMonitor * volatile ObjectSynchronizer::gBlockList = NULL;
// global monitor free list
ObjectMonitor * volatile ObjectSynchronizer::gFreeList = NULL;
// global monitor in-use list, for moribund threads,
@ -890,21 +890,22 @@ JavaThread* ObjectSynchronizer::get_lock_owner(Handle h_obj, bool doLock) {
return NULL;
}
// Visitors ...
void ObjectSynchronizer::monitors_iterate(MonitorClosure* closure) {
PaddedEnd<ObjectMonitor> * block = (PaddedEnd<ObjectMonitor> *)gBlockList;
ObjectMonitor* mid;
while (block) {
PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)OrderAccess::load_ptr_acquire(&gBlockList);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
for (int i = _BLOCKSIZE - 1; i > 0; i--) {
mid = (ObjectMonitor *)(block + i);
oop object = (oop) mid->object();
ObjectMonitor* mid = (ObjectMonitor *)(block + i);
oop object = (oop)mid->object();
if (object != NULL) {
closure->do_monitor(mid);
}
}
block = (PaddedEnd<ObjectMonitor> *) block->FreeNext;
block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
}
}
@ -919,9 +920,9 @@ static inline ObjectMonitor* next(ObjectMonitor* block) {
void ObjectSynchronizer::oops_do(OopClosure* f) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
for (PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)gBlockList; block != NULL;
block = (PaddedEnd<ObjectMonitor> *)next(block)) {
PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)OrderAccess::load_ptr_acquire(&gBlockList);
for (; block != NULL; block = (PaddedEnd<ObjectMonitor> *)next(block)) {
assert(block->object() == CHAINMARKER, "must be a block header");
for (int i = 1; i < _BLOCKSIZE; i++) {
ObjectMonitor* mid = (ObjectMonitor *)&block[i];
@ -1139,7 +1140,9 @@ ObjectMonitor * NOINLINE ObjectSynchronizer::omAlloc(Thread * Self) {
// The very first objectMonitor in a block is reserved and dedicated.
// It serves as blocklist "next" linkage.
temp[0].FreeNext = gBlockList;
gBlockList = temp;
// There are lock-free uses of gBlockList so make sure that
// the previous stores happen before we update gBlockList.
OrderAccess::release_store_ptr(&gBlockList, temp);
// Add the new string of objectMonitors to the global free list
temp[_BLOCKSIZE - 1].FreeNext = gFreeList;
@ -1621,31 +1624,33 @@ void ObjectSynchronizer::deflate_idle_monitors() {
nInuse += gOmInUseCount;
}
} else for (PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)gBlockList; block != NULL;
block = (PaddedEnd<ObjectMonitor> *)next(block)) {
// Iterate over all extant monitors - Scavenge all idle monitors.
assert(block->object() == CHAINMARKER, "must be a block header");
nInCirculation += _BLOCKSIZE;
for (int i = 1; i < _BLOCKSIZE; i++) {
ObjectMonitor* mid = (ObjectMonitor*)&block[i];
oop obj = (oop) mid->object();
} else {
PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)OrderAccess::load_ptr_acquire(&gBlockList);
for (; block != NULL; block = (PaddedEnd<ObjectMonitor> *)next(block)) {
// Iterate over all extant monitors - Scavenge all idle monitors.
assert(block->object() == CHAINMARKER, "must be a block header");
nInCirculation += _BLOCKSIZE;
for (int i = 1; i < _BLOCKSIZE; i++) {
ObjectMonitor* mid = (ObjectMonitor*)&block[i];
oop obj = (oop)mid->object();
if (obj == NULL) {
// The monitor is not associated with an object.
// The monitor should either be a thread-specific private
// free list or the global free list.
// obj == NULL IMPLIES mid->is_busy() == 0
guarantee(!mid->is_busy(), "invariant");
continue;
}
deflated = deflate_monitor(mid, obj, &freeHeadp, &freeTailp);
if (obj == NULL) {
// The monitor is not associated with an object.
// The monitor should either be a thread-specific private
// free list or the global free list.
// obj == NULL IMPLIES mid->is_busy() == 0
guarantee(!mid->is_busy(), "invariant");
continue;
}
deflated = deflate_monitor(mid, obj, &freeHeadp, &freeTailp);
if (deflated) {
mid->FreeNext = NULL;
nScavenged++;
} else {
nInuse++;
if (deflated) {
mid->FreeNext = NULL;
nScavenged++;
} else {
nInuse++;
}
}
}
}
@ -1789,18 +1794,18 @@ void ObjectSynchronizer::sanity_checks(const bool verbose,
// Verify all monitors in the monitor cache, the verification is weak.
void ObjectSynchronizer::verify() {
PaddedEnd<ObjectMonitor> * block = (PaddedEnd<ObjectMonitor> *)gBlockList;
ObjectMonitor* mid;
while (block) {
PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)OrderAccess::load_ptr_acquire(&gBlockList);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
for (int i = 1; i < _BLOCKSIZE; i++) {
mid = (ObjectMonitor *)(block + i);
oop object = (oop) mid->object();
ObjectMonitor* mid = (ObjectMonitor *)(block + i);
oop object = (oop)mid->object();
if (object != NULL) {
mid->verify();
}
}
block = (PaddedEnd<ObjectMonitor> *) block->FreeNext;
block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
}
}
@ -1809,19 +1814,19 @@ void ObjectSynchronizer::verify() {
// the list of extant blocks without taking a lock.
int ObjectSynchronizer::verify_objmon_isinpool(ObjectMonitor *monitor) {
PaddedEnd<ObjectMonitor> * block = (PaddedEnd<ObjectMonitor> *)gBlockList;
while (block) {
PaddedEnd<ObjectMonitor> * block =
(PaddedEnd<ObjectMonitor> *)OrderAccess::load_ptr_acquire(&gBlockList);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
if (monitor > (ObjectMonitor *)&block[0] &&
monitor < (ObjectMonitor *)&block[_BLOCKSIZE]) {
address mon = (address) monitor;
address blk = (address) block;
address mon = (address)monitor;
address blk = (address)block;
size_t diff = mon - blk;
assert((diff % sizeof(PaddedEnd<ObjectMonitor>)) == 0, "check");
assert((diff % sizeof(PaddedEnd<ObjectMonitor>)) == 0, "must be aligned");
return 1;
}
block = (PaddedEnd<ObjectMonitor> *) block->FreeNext;
block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
}
return 0;
}