[moderation] [mm?] [fs?] KCSAN: data-race in write_cache_pages / write_cache_pages (12)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 135288b73cef Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1766460a180000
kernel config: https://syzkaller.appspot.com/x/.config?x=f10ff55d327ef698
dashboard link: https://syzkaller.appspot.com/bug?extid=dec8bb81077145a6fa94
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/232ed5f6c6ce/disk-135288b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/48e0b8da75f4/vmlinux-135288b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a1abbe53f091/bzImage-135288b7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dec8bb...@syzkaller.appspotmail.com

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

write to 0xffff8881004c0bb8 of 8 bytes by task 3086 on cpu 1:
write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
blkdev_writepages+0x59/0x90 block/fops.c:426
do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:388
__filemap_fdatawrite_range mm/filemap.c:421 [inline]
__filemap_fdatawrite mm/filemap.c:427 [inline]
filemap_flush+0x95/0xc0 mm/filemap.c:454
sync_blockdev_nowait+0x36/0x50 block/bdev.c:189
sync_filesystem+0xe0/0x180 fs/sync.c:60
generic_shutdown_super+0x42/0x210 fs/super.c:620
kill_block_super+0x2a/0x60 fs/super.c:1675
ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7319
deactivate_locked_super+0x7a/0x1c0 fs/super.c:472
deactivate_super+0x9b/0xb0 fs/super.c:505
cleanup_mnt+0x272/0x2e0 fs/namespace.c:1267
__cleanup_mnt+0x19/0x20 fs/namespace.c:1274
task_work_run+0x135/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:108 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
syscall_exit_to_user_mode+0xbd/0x120 kernel/entry/common.c:212
do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff8881004c0bb8 of 8 bytes by task 48 on cpu 0:
write_cache_pages+0x6f3/0x740 mm/page-writeback.c:2527
blkdev_writepages+0x59/0x90 block/fops.c:426
do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
__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:2633 [inline]
process_scheduled_works+0x5b8/0xa40 kernel/workqueue.c:2706
worker_thread+0x525/0x730 kernel/workqueue.c:2787
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:243

value changed: 0x0000000000000000 -> 0x0000000000000029

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 48 Comm: kworker/u4:3 Not tainted 6.8.0-rc7-syzkaller-00130-g135288b73cef #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Workqueue: writeback wb_workfn (flush-7:0)
==================================================================


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[syzbot]

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