[moderation] [mm?] [fs?] KCSAN: data-race in write_cache_pages / write_cache_pages (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 815fb87b7530 Merge tag 'pm-6.7-rc4' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1708c7c2e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=efc18f367a3f97fa
dashboard link: https://syzkaller.appspot.com/bug?extid=b6cf56329102bc7a5fc7
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.org wi...@infradead.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98392298dffb/disk-815fb87b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4acd42758037/vmlinux-815fb87b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c9706d8d14f0/bzImage-815fb87b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b6cf56...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in write_cache_pages / write_cache_pages

write to 0xffff8881006324b8 of 8 bytes by task 3100 on cpu 0:
write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
do_writepages+0x20f/0x340 mm/page-writeback.c:2558
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
__filemap_fdatawrite mm/filemap.c:426 [inline]
filemap_flush+0x95/0xc0 mm/filemap.c:453
sync_blockdev_nowait+0x36/0x50 block/bdev.c:186
sync_filesystem+0xe0/0x180 fs/sync.c:60
generic_shutdown_super+0x42/0x210 fs/super.c:669
kill_block_super+0x2a/0x60 fs/super.c:1667
ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7330
deactivate_locked_super+0x7a/0x1c0 fs/super.c:484
deactivate_super+0x9b/0xb0 fs/super.c:517
cleanup_mnt+0x272/0x2e0 fs/namespace.c:1256
__cleanup_mnt+0x19/0x20 fs/namespace.c:1263
task_work_run+0x135/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xd6/0xe0 kernel/entry/common.c:171
exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296
do_syscall_64+0x50/0x110 arch/x86/entry/common.c:88
entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff8881006324b8 of 8 bytes by task 11 on cpu 1:
write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
do_writepages+0x20f/0x340 mm/page-writeback.c:2558
__writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1625
writeback_sb_inodes+0x514/0xad0 fs/fs-writeback.c:1916
__writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:1987
wb_writeback+0x264/0x6e0 fs/fs-writeback.c:2094
wb_check_background_flush fs/fs-writeback.c:2164 [inline]
wb_do_writeback fs/fs-writeback.c:2252 [inline]
wb_workfn+0x67f/0x8d0 fs/fs-writeback.c:2279
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

value changed: 0x0000000000000000 -> 0x0000000000000029

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11 Comm: kworker/u4:0 Tainted: G W 6.7.0-rc3-syzkaller-00284-g815fb87b7530 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Workqueue: writeback wb_workfn (flush-7:5)
==================================================================


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[syzbot]

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