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KCSAN: data-race in fsnotify / fsnotify_detach_mark (10)

Status: moderation: reported on 2026/03/07 07:53
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+4d3a08edcc44ff216ac1@syzkaller.appspotmail.com
First crash: 6d17h, last: 6d17h
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
18770b9b-075e-420f-8c42-b57db830e15d assessment-kcsan Benign: ✅  Confident: ✅  ❓ KCSAN: data-race in fsnotify / fsnotify_detach_mark (10) 2026/03/07 08:00 2026/03/07 08:00 2026/03/07 08:03 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (5) fs 6 2 1936d 1922d 0/29 auto-closed as invalid on 2020/12/28 12:08
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (4) fs 6 1 1992d 1992d 0/29 auto-closed as invalid on 2020/11/02 17:43
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (8) fs 6 1 1540d 1540d 0/29 auto-closed as invalid on 2022/01/29 00:14
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark fs 6 6 2149d 2295d 0/29 auto-closed as invalid on 2020/06/18 13:43
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (7) fs 6 1 1620d 1620d 0/29 auto-closed as invalid on 2021/11/09 20:25
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (6) fs 6 1 1894d 1894d 0/29 auto-closed as invalid on 2021/02/08 06:39
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (2) fs 6 1 2086d 2086d 0/29 auto-closed as invalid on 2020/07/31 05:33
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (9) fs 6 31 1145d 1385d 0/29 auto-obsoleted due to no activity on 2023/04/10 23:59
upstream KCSAN: data-race in fsnotify / fsnotify_detach_mark (3) fs 6 1 2036d 2036d 0/29 auto-closed as invalid on 2020/09/19 20:21

Sample crash report:
==================================================================
BUG: KCSAN: data-race in fsnotify / fsnotify_detach_mark

write to 0xffff888105359684 of 4 bytes by task 454 on cpu 0:
 fsnotify_detach_mark+0xb9/0x160 fs/notify/mark.c:558
 fsnotify_clear_marks_by_group+0x301/0x4b0 fs/notify/mark.c:1031
 fsnotify_destroy_group+0x53/0x180 fs/notify/group.c:61
 inotify_release+0x1f/0x30 fs/notify/inotify/inotify_user.c:308
 __fput+0x29b/0x650 fs/file_table.c:469
 ____fput+0x1c/0x30 fs/file_table.c:497
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x4ae/0x1600 kernel/exit.c:976
 do_group_exit+0xfe/0x140 kernel/exit.c:1118
 get_signal+0xe54/0xf60 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105359684 of 4 bytes by task 441 on cpu 1:
 send_to_group fs/notify/fsnotify.c:349 [inline]
 fsnotify+0xd77/0x1730 fs/notify/fsnotify.c:592
 __fsnotify_parent+0x358/0x3a0 fs/notify/fsnotify.c:238
 fsnotify_parent include/linux/fsnotify.h:96 [inline]
 fsnotify_path include/linux/fsnotify.h:113 [inline]
 fsnotify_file include/linux/fsnotify.h:127 [inline]
 fsnotify_modify include/linux/fsnotify.h:433 [inline]
 __kernel_write_iter+0x4c9/0x590 fs/read_write.c:625
 dump_emit_page fs/coredump.c:1299 [inline]
 dump_user_range+0xa7d/0xdb0 fs/coredump.c:1373
 elf_core_dump+0x21a2/0x2330 fs/binfmt_elf.c:2110
 coredump_write+0xacc/0xdd0 fs/coredump.c:1050
 do_coredump fs/coredump.c:1127 [inline]
 vfs_coredump+0x26c7/0x3130 fs/coredump.c:1201
 get_signal+0xd80/0xf60 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000013 -> 0x00000010

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 441 Comm: syz.7.13551 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/07 07:52 upstream 651690480a96 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fsnotify / fsnotify_detach_mark
* Struck through repros no longer work on HEAD.