syzbot


panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:

Status: fixed on 2025/09/17 13:21
Fix commit: 2c49d9fd3897 kernel: fix circular locking in FSContext.destroy
First crash: 7d12h, last: 2d15h

Sample crash report:
panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
	goroutine 40877 [running]:
	gvisor.dev/gvisor/pkg/sync/locking.(*ancestorsAtomicPtrMap).RangeRepeatable(0xc00048f3d0, 0xc0010314a8)
		bazel-out/k8-fastbuild/bin/pkg/sync/locking/atomicptrmap_ancestors_unsafe.go:440 +0x314
	gvisor.dev/gvisor/pkg/sync/locking.checkLock(0xc00027cd80, 0xc00048f3b0, {0xc0015160d8, 0x1, 0x1})
		pkg/sync/locking/lockdep.go:112 +0x4eb
	gvisor.dev/gvisor/pkg/sync/locking.checkLock.func1(0xc00048f3b0, 0xc001031638?)
		pkg/sync/locking/lockdep.go:115 +0x74
	gvisor.dev/gvisor/pkg/sync/locking.(*ancestorsAtomicPtrMap).RangeRepeatable(0xc00048f190, 0xc0010316e8)
		bazel-out/k8-fastbuild/bin/pkg/sync/locking/atomicptrmap_ancestors_unsafe.go:440 +0x314
	gvisor.dev/gvisor/pkg/sync/locking.checkLock(0xc00027cd80, 0xc00048f170, {0x0, 0x0, 0x0})
		pkg/sync/locking/lockdep.go:112 +0x4eb
	gvisor.dev/gvisor/pkg/sync/locking.AddGLock(0xc00027cd80, 0xffffffffffffffff)
		pkg/sync/locking/lockdep.go:144 +0x37b
	gvisor.dev/gvisor/pkg/sentry/vfs.(*inotifyEventMutex).Lock(0xc002a3e098)
		bazel-out/k8-fastbuild/bin/pkg/sentry/vfs/inotify_event_mutex.go:33 +0x4d
	gvisor.dev/gvisor/pkg/sentry/vfs.(*Inotify).queueEvent(0xc002a3e000, 0xc001780380)
		pkg/sentry/vfs/inotify.go:276 +0x4e
	gvisor.dev/gvisor/pkg/sentry/vfs.(*Watches).HandleDeletion(0xc0024447a0, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/vfs/inotify.go:537 +0x2fc
	gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*inode).decRef.func1()
		pkg/sentry/fsimpl/tmpfs/tmpfs.go:605 +0x65
	gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*inodeRefs).DecRef(0xc002444460, 0xc001031b10)
		bazel-out/k8-fastbuild/bin/pkg/sentry/fsimpl/tmpfs/inode_refs.go:133 +0xb4
	gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*inode).decRef(0xc002444458, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/fsimpl/tmpfs/tmpfs.go:604 +0xa5
	gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*dentry).DecRef(0xc002444408, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/fsimpl/tmpfs/tmpfs.go:464 +0x65
	gvisor.dev/gvisor/pkg/sentry/vfs.(*Dentry).DecRef(0xc002444408, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/vfs/dentry.go:156 +0x68
	gvisor.dev/gvisor/pkg/sentry/vfs.VirtualDentry.DecRef({0xc00071c840?, 0xc002444408?}, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/vfs/vfs.go:1114 +0x5b
	gvisor.dev/gvisor/pkg/sentry/kernel.(*FSContext).destroy(0xc0018af900, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/kernel/fs_context.go:73 +0x16d
	gvisor.dev/gvisor/pkg/sentry/kernel.(*FSContext).DecRef.func1()
		pkg/sentry/kernel/fs_context.go:87 +0x59
	gvisor.dev/gvisor/pkg/sentry/kernel.(*FSContextRefs).DecRef(0xc0018af900, 0xc001031d10)
		bazel-out/k8-fastbuild/bin/pkg/sentry/kernel/fs_context_refs.go:133 +0xb4
	gvisor.dev/gvisor/pkg/sentry/kernel.(*FSContext).DecRef(0xc0018af900, {0x21b8bb0, 0xc0014fcc88})
		pkg/sentry/kernel/fs_context.go:86 +0xa5
	gvisor.dev/gvisor/pkg/sentry/kernel.(*runExitMain).execute(0xc0014fcc88?, 0xc0014fcc88)
		pkg/sentry/kernel/task_exit.go:301 +0x7d3
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0014fcc88, 0x2888)
		pkg/sentry/kernel/task_run.go:97 +0x402
	created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 40941
		pkg/sentry/kernel/task_start.go:416 +0x17e
	
	known lock chain: vfs.inotifyEventMutex -> mm.mappingRWMutex -> kernel.taskMutex -> kernel.fsContextMutex
	
	====== vfs.inotifyEventMutex -> mm.mappingRWMutex =====
	goroutine 40941 [running]:
	gvisor.dev/gvisor/pkg/sentry/mm.(*mappingRWMutex).RLock(0xc000b6305c)
		bazel-out/k8-fastbuild/bin/pkg/sentry/mm/mapping_mutex.go:59 +0x4d
	gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).withInternalMappings(0xc000b63008, {0x21b8bb0, 0xc002560008}, {0xc00075aef0?, 0x41465d?}, {0x6c?, 0x86?, 0x48?}, 0x0, 0xc00075af38)
		pkg/sentry/mm/io.go:545 +0x145
	gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).CopyOut(0xc000b63008, {0x21b8bb0, 0xc002560008}, 0x200000001fc0, {0xc002508340, 0x10, 0x10}, {0x1?, 0x0?})
		pkg/sentry/mm/io.go:130 +0x2e7
	gvisor.dev/gvisor/pkg/usermem.CopyOutVec({0x21b8bb0, 0xc002560008}, {0x21ae538, 0xc000b63008}, {0x0?, 0xa00a15?, 0x48866c?, 0x48a355?}, {0xc002508340, 0x10, ...}, ...)
		pkg/usermem/usermem.go:264 +0x26b
	gvisor.dev/gvisor/pkg/usermem.IOSequence.CopyOut({{0x21ae538, 0xc000b63008}, {0x0, 0x1, 0x200000001fc0, 0x30}, {0x0, 0x1}}, {0x21b8bb0, 0xc002560008}, ...)
		pkg/usermem/usermem.go:482 +0xe8
	gvisor.dev/gvisor/pkg/sentry/vfs.(*Event).CopyTo(0xc0018aee40, {0x21b8bb0, 0xc002560008}, {0xc002508340, 0x10, 0x10}, {{0x21ae538, 0xc000b63008}, {0x0, 0x1, ...}, ...})
		pkg/sentry/vfs/inotify.go:693 +0x5a5
	gvisor.dev/gvisor/pkg/sentry/vfs.(*Inotify).Read(0xc002a3e000, {0x21b8bb0, 0xc002560008}, {{0x21ae538, 0xc000b63008}, {0x0, 0x1, 0x200000001fc0, 0x30}, {0x0, ...}}, ...)
		pkg/sentry/vfs/inotify.go:244 +0x632
	gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Read(0xc002a3e000, {0x21b8bb0, 0xc002560008}, {{0x21ae538, 0xc000b63008}, {0x0, 0x1, 0x200000001fc0, 0x30}, {0x0, ...}}, ...)
		pkg/sentry/vfs/file_description.go:653 +0x154
	gvisor.dev/gvisor/pkg/sentry/syscalls/linux.read(0xc002560008, 0xc002a3e000, {{0x21ae538, 0xc000b63008}, {0x0, 0x1, 0x200000001fc0, 0x30}, {0x0, 0x1}}, ...)
		pkg/sentry/syscalls/linux/sys_read_write.go:93 +0xa5
	gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Read(0xc002560008, 0x457b27?, {{0x3}, {0x200000001fc0}, {0x30}, {0x0}, {0x0}, {0x0}})
		pkg/sentry/syscalls/linux/sys_read_write.go:62 +0x38f
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc002560008, 0x0, {{0x3}, {0x200000001fc0}, {0x30}, {0x0}, {0x0}, {0x0}})
		pkg/sentry/kernel/task_syscall.go:143 +0xb90
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc002560008, 0x0, {{0x3}, {0x200000001fc0}, {0x30}, {0x0}, {0x0}, {0x0}})
		pkg/sentry/kernel/task_syscall.go:323 +0x85
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc002560008, 0x0, {{0x3}, {0x200000001fc0}, {0x30}, {0x0}, {0x0}, {0x0}})
		pkg/sentry/kernel/task_syscall.go:283 +0xc7
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc002560008)
		pkg/sentry/kernel/task_syscall.go:258 +0x53e
	gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc002560008?, 0xc002560008)
		pkg/sentry/kernel/task_run.go:269 +0x220c
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc002560008, 0x2884)
		pkg/sentry/kernel/task_run.go:97 +0x402
	created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 40965
		pkg/sentry/kernel/task_start.go:416 +0x17e
	
	====== mm.mappingRWMutex -> kernel.taskMutex =====
	goroutine 3869 [running]:
	gvisor.dev/gvisor/pkg/sentry/kernel.(*taskMutex).Lock(0xc001261620)
		bazel-out/k8-fastbuild/bin/pkg/sentry/kernel/task_mutex.go:35 +0x4d
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).contextValue(0xc001260c88, {0x1cdae00, 0x2187720}, 0x0)
		pkg/sentry/kernel/task_context.go:96 +0x1236
	gvisor.dev/gvisor/pkg/sentry/kernel.(*taskAsyncContext).Value(0xc00154fe90, {0x1cdae00, 0x2187720})
		pkg/sentry/kernel/task_context.go:159 +0x65
	gvisor.dev/gvisor/pkg/sentry/vfs.RootFromContext({0x7f421531e148, 0xc00154fe90})
		pkg/sentry/vfs/context.go:88 +0x58
	gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).MappedName(0xc000918c00, {0x21b8c48, 0xc00154fe90})
		pkg/sentry/vfs/file_description.go:818 +0x78
	gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).appendVMAMapsEntryLocked(0xc000c66990?, {0x21b8c48, 0xc00154fe90}, {0xc001a76008?, 0xc00174f330?}, 0xc00171b780)
		pkg/sentry/mm/procfs.go:129 +0x32c
	gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).vmaSmapsEntryIntoLocked(0xc001372008, {0x21b8c48, 0xc00154fe90}, {0xc001a76008?, 0x48866c?}, 0xc0010042c0)
		pkg/sentry/mm/procfs.go:160 +0xb5
	gvisor.dev/gvisor/pkg/sentry/mm.(*MemoryManager).ReadSmapsDataInto(0xc001372008, {0x21b8c48, 0xc00154fe90}, 0xc0010042c0)
		pkg/sentry/mm/procfs.go:141 +0x12e
	gvisor.dev/gvisor/pkg/sentry/fsimpl/proc.(*smapsData).Generate(0xc00127a008, {0x21b8c48, 0xc00154fe90}, 0xc0010042c0)
		pkg/sentry/fsimpl/proc/task_files.go:670 +0x9e
	gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).preadLocked(0xc0010042a0, {0x21b8c48, 0xc00154fe90}, {{0x21ae538, 0xc001372008}, {0x0, 0x0, 0x0, 0x0}, {0x0, ...}}, ...)
		pkg/sentry/vfs/file_description_impl_util.go:310 +0x1d9
	gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).PRead(0xc0010042a0, {0x21b8c48, 0xc00154fe90}, {{0x21ae538, 0xc001372008}, {0x0, 0x0, 0x0, 0x0}, {0x0, ...}}, ...)
		pkg/sentry/vfs/file_description_impl_util.go:329 +0xd5
	gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*DynamicBytesFD).PRead(0xc0010042a0, {0x21b8c48, 0xc00154fe90}, {{0x21ae538, 0xc001372008}, {0x0, 0x0, 0x0, 0x0}, {0x0, ...}}, ...)
		pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go:133 +0xb7
	gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).PRead(0xc001004300, {0x21b8c48, 0xc00154fe90}, {{0x21ae538, 0xc001372008}, {0x0, 0x0, 0x0, 0x0}, {0x0, ...}}, ...)
		pkg/sentry/vfs/file_description.go:638 +0x19b
	gvisor.dev/gvisor/pkg/sentry/syscalls/linux.getAIOCallback.func1({0x21b8c48, 0xc00154fe90})
		pkg/sentry/syscalls/linux/sys_aio.go:361 +0x3f4
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).QueueAIO.func1()
		pkg/sentry/kernel/aio.go:30 +0x62
	created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).QueueAIO in goroutine 3882
		pkg/sentry/kernel/aio.go:29 +0x225
	
	====== kernel.taskMutex -> kernel.fsContextMutex =====
	goroutine 252 [running]:
	gvisor.dev/gvisor/pkg/sentry/kernel.(*fsContextMutex).Lock(0xc000711dc8)
		bazel-out/k8-fastbuild/bin/pkg/sentry/kernel/fs_context_mutex.go:33 +0x4d
	gvisor.dev/gvisor/pkg/sentry/kernel.(*FSContext).Fork(0xc000711dc0)
		pkg/sentry/kernel/fs_context.go:95 +0x65
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Unshare(0xc000d4e588, 0x20000)
		pkg/sentry/kernel/task_clone.go:706 +0x1207
	gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Unshare(0xc000d4e588, 0x457b27?, {{0x20000}, {0x7}, {0x7f1ef864caf0}, {0x0}, {0x0}, {0x558ad77756c0}})
		pkg/sentry/syscalls/linux/sys_thread.go:453 +0xd5
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc000d4e588, 0x110, {{0x20000}, {0x7}, {0x7f1ef864caf0}, {0x0}, {0x0}, {0x558ad77756c0}})
		pkg/sentry/kernel/task_syscall.go:143 +0xb90
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc000d4e588, 0x110, {{0x20000}, {0x7}, {0x7f1ef864caf0}, {0x0}, {0x0}, {0x558ad77756c0}})
		pkg/sentry/kernel/task_syscall.go:323 +0x85
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc000d4e588, 0x110, {{0x20000}, {0x7}, {0x7f1ef864caf0}, {0x0}, {0x0}, {0x558ad77756c0}})
		pkg/sentry/kernel/task_syscall.go:283 +0xc7
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc000d4e588)
		pkg/sentry/kernel/task_syscall.go:258 +0x53e
	gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc000d4e588?, 0xc000d4e588)
		pkg/sentry/kernel/task_run.go:269 +0x220c
	gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc000d4e588, 0xd)
		pkg/sentry/kernel/task_run.go:97 +0x402
	created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 76
		pkg/sentry/kernel/task_start.go:416 +0x17e
	

Crashes (16):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/16 19:43 gvisor 0bb00ae3d273 e2beed91 .config console log report info ci-gvisor-ptrace-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/16 18:55 gvisor 0bb00ae3d273 e2beed91 .config console log report info ci-gvisor-ptrace-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/16 16:23 gvisor 0bb00ae3d273 e2beed91 .config console log report info ci-gvisor-ptrace-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/16 02:17 gvisor 9041e2310cf4 e2beed91 .config console log report info ci-gvisor-ptrace-3-race panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/15 16:21 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-2-race panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/14 08:41 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/14 01:41 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-2-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/14 01:09 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-systrap-1-race panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/13 22:16 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-systrap-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/13 13:51 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-2-race panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/13 09:32 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-2-race panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/12 13:37 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-systrap-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/12 05:43 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-2-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/12 03:50 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-2-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/11 22:58 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-ptrace-1-race-cover panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
2025/09/12 06:33 gvisor 57697a8f6350 e2beed91 .config console log report info ci-gvisor-arm64-ptrace-1-race panic: WARNING: circular locking detected: kernel.fsContextMutex -> vfs.inotifyEventMutex:
* Struck through repros no longer work on HEAD.