[moderation] [mm?] [fs?] KCSAN: data-race in filemap_flush / xas_set_mark (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 62b5a46999c7 Merge tag '6.13-rc1-smb3-client-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124cc8f8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ff022027cd3a0001
dashboard link: https://syzkaller.appspot.com/bug?extid=7764a17262a8bb14bd80
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/d886c5d5e278/disk-62b5a469.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0303aa72049c/vmlinux-62b5a469.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5706a95aa0b0/bzImage-62b5a469.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7764a1...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in filemap_flush / xas_set_mark

write to 0xffff8881004c1e24 of 4 bytes by task 3412 on cpu 1:
xa_mark_set lib/xarray.c:71 [inline]
xas_set_mark+0x131/0x150 lib/xarray.c:893
__folio_start_writeback+0x1e8/0x430 mm/page-writeback.c:3141
__block_write_full_folio+0x506/0x8c0 fs/buffer.c:1899
block_write_full_folio+0x293/0x2b0
write_cache_pages+0x62/0x100 mm/page-writeback.c:2659
blkdev_writepages+0x59/0x90 block/fops.c:433
do_writepages+0x1d8/0x480 mm/page-writeback.c:2702
__writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1976
__writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2047
wb_writeback+0x274/0x640 fs/fs-writeback.c:2158
wb_check_background_flush fs/fs-writeback.c:2228 [inline]
wb_do_writeback fs/fs-writeback.c:2316 [inline]
wb_workfn+0x67f/0x940 fs/fs-writeback.c:2343
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881004c1e24 of 4 bytes by task 3300 on cpu 0:
xa_marked include/linux/xarray.h:424 [inline]
mapping_tagged include/linux/fs.h:504 [inline]
filemap_fdatawrite_wbc mm/filemap.c:393 [inline]
__filemap_fdatawrite_range mm/filemap.c:430 [inline]
__filemap_fdatawrite mm/filemap.c:436 [inline]
filemap_flush+0x9a/0x120 mm/filemap.c:463
sync_blockdev_nowait+0x29/0x40 block/bdev.c:207
sync_filesystem+0xe3/0x190 fs/sync.c:60
generic_shutdown_super+0x46/0x220 fs/super.c:621
kill_block_super+0x2a/0x70 fs/super.c:1710
deactivate_locked_super+0x7d/0x1c0 fs/super.c:473
deactivate_super+0x9f/0xb0 fs/super.c:506
cleanup_mnt+0x268/0x2e0 fs/namespace.c:1373
__cleanup_mnt+0x19/0x20 fs/namespace.c:1380
task_work_run+0x13a/0x1a0 kernel/task_work.c:239
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xa8/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x02000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3300 Comm: syz-executor Not tainted 6.13.0-rc1-syzkaller-00378-g62b5a46999c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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