syzbot


KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (9)

Status: moderation: reported on 2026/02/12 02:29
Subsystems: ext4 exfat
[Documentation on labels]
Reported-by: syzbot+f675e69be7135b609a50@syzkaller.appspotmail.com
First crash: 38d, last: 11d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
7be8049a-9771-4ab7-8c14-7f4a4f129e1f assessment-kcsan Benign: ✅  Confident: ✅  KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (9) 2026/02/12 16:25 2026/02/13 13:11 2026/02/13 13:13 54290dbc8f9e8d4533df2bb39cf823e93897fb2c
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (4) ext4 6 80 691d 836d 0/29 auto-obsoleted due to no activity on 2024/06/03 21:44
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (8) ext4 6 9 108d 280d 0/29 auto-obsoleted due to no activity on 2026/01/28 21:28
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (3) fs 6 1 1128d 1128d 0/29 auto-obsoleted due to no activity on 2023/04/01 03:15
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (5) ext4 6 13 518d 634d 0/29 auto-obsoleted due to no activity on 2024/11/24 11:50
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru fs 6 14 2236d 2303d 0/29 auto-closed as invalid on 2020/04/15 20:03
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (2) ext4 exfat 6 213 1172d 1632d 0/29 auto-obsoleted due to no activity on 2023/02/08 20:39
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (6) ext4 6 1 479d 479d 0/29 auto-obsoleted due to no activity on 2025/01/22 20:51
upstream KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru (7) ext4 6 6 341d 414d 0/29 auto-obsoleted due to no activity on 2025/06/09 21:46

Sample crash report:
EXT4-fs (loop6): unmounting filesystem 00000000-0000-0000-0000-000000000000.
==================================================================
BUG: KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru

write to 0xffff888237c27760 of 8 bytes by task 13519 on cpu 0:
 __invalidate_bh_lrus fs/buffer.c:1526 [inline]
 invalidate_bh_lru+0x89/0xe0 fs/buffer.c:1538
 csd_do_func kernel/smp.c:136 [inline]
 smp_call_function_many_cond+0x743/0xc30 kernel/smp.c:868
 on_each_cpu_cond_mask+0x3c/0x80 kernel/smp.c:1043
 on_each_cpu_cond include/linux/smp.h:106 [inline]
 invalidate_bh_lrus+0x2a/0x30 fs/buffer.c:1557
 invalidate_bdev+0x42/0x70 block/bdev.c:100
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1353
 generic_shutdown_super+0xee/0x220 fs/super.c:646
 kill_block_super+0x2a/0x70 fs/super.c:1725
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7459
 deactivate_locked_super+0x75/0x1c0 fs/super.c:476
 deactivate_super+0x97/0xa0 fs/super.c:509
 cleanup_mnt+0x2bb/0x330 fs/namespace.c:1312
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1319
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x1f4/0x6f0 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 0xffff888237c27760 of 8 bytes by task 13304 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1548
 smp_call_function_many_cond+0x2c1/0xc30 kernel/smp.c:821
 on_each_cpu_cond_mask+0x3c/0x80 kernel/smp.c:1043
 on_each_cpu_cond include/linux/smp.h:106 [inline]
 invalidate_bh_lrus+0x2a/0x30 fs/buffer.c:1557
 invalidate_bdev+0x42/0x70 block/bdev.c:100
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1353
 generic_shutdown_super+0xee/0x220 fs/super.c:646
 kill_block_super+0x2a/0x70 fs/super.c:1725
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7459
 deactivate_locked_super+0x75/0x1c0 fs/super.c:476
 deactivate_super+0x97/0xa0 fs/super.c:509
 cleanup_mnt+0x2bb/0x330 fs/namespace.c:1312
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1319
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x1f4/0x6f0 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: 0xffff8881064485b0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13304 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
EXT4-fs (loop6): unmounting filesystem 00000000-0000-0000-0000-000000000000.

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/10 15:13 upstream 1f318b96cc84 4683d576 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru
2026/02/12 02:28 upstream c22e26bd0906 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru
* Struck through repros no longer work on HEAD.