[moderation] [fs?] KCSAN: data-race in has_bh_in_lru / invalidate_bh_lrus_cpu (15)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cd2e103d57e5 Merge tag 'hardening-v6.16-rc1-fix1-take2' of..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=108e580c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a8f90f190239c35c
dashboard link: https://syzkaller.appspot.com/bug?extid=c81b6ee731e9ce8df649
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2dea1049fe27/disk-cd2e103d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9bbcc26e5a40/vmlinux-cd2e103d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fa17e0b8c8c0/bzImage-cd2e103d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c81b6e...@syzkaller.appspotmail.com

EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.
==================================================================
BUG: KCSAN: data-race in has_bh_in_lru / invalidate_bh_lrus_cpu

write to 0xffff888237d26f10 of 8 bytes by task 3392 on cpu 1:
__invalidate_bh_lrus fs/buffer.c:1535 [inline]
invalidate_bh_lrus_cpu+0x89/0xc0 fs/buffer.c:1580
lru_add_and_bh_lrus_drain mm/swap.c:746 [inline]
lru_add_drain_per_cpu+0x55/0x70 mm/swap.c:765
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
worker_thread+0x582/0x770 kernel/workqueue.c:3402
kthread+0x486/0x510 kernel/kthread.c:464
ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888237d26f10 of 8 bytes by task 5687 on cpu 0:
has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1557
smp_call_function_many_cond+0x38c/0xbf0 kernel/smp.c:838
on_each_cpu_cond_mask+0x3c/0x80 kernel/smp.c:1052
on_each_cpu_cond include/linux/smp.h:105 [inline]
invalidate_bh_lrus+0x2a/0x30 fs/buffer.c:1566
kill_bdev block/bdev.c:90 [inline]
blkdev_flush_mapping+0x9a/0x1a0 block/bdev.c:712
blkdev_put_whole block/bdev.c:719 [inline]
bdev_release+0x2bf/0x3d0 block/bdev.c:1144
blkdev_release+0x15/0x20 block/fops.c:684
__fput+0x29b/0x650 fs/file_table.c:465
____fput+0x1c/0x30 fs/file_table.c:493
task_work_run+0x12e/0x1a0 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888106a2ebc8 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5687 Comm: syz-executor Not tainted 6.15.0-syzkaller-10820-gcd2e103d57e5 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.