[moderation] [fs?] [mm?] upstream test error: KCSAN: data-race in __xa_clear_mark / xas_find_marked (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ecc64d2dc9ff Merge tag 'sysctl-7.00-fixes-rc3' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=168c9b5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6b32b22d8934c136
dashboard link: https://syzkaller.appspot.com/bug?extid=4b18e0ba685915be998c
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.org wi...@infradead.org]

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/876efb5d0da9/disk-ecc64d2d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/02da6f07847d/vmlinux-ecc64d2d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/29b1856f7554/bzImage-ecc64d2d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4b18e0...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff888107a25228 of 8 bytes by task 40 on cpu 0:
instrument_read_write include/linux/instrumented.h:56 [inline]
__instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:84 [inline]
___test_and_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:114 [inline]
node_clear_mark lib/xarray.c:102 [inline]
xas_clear_mark lib/xarray.c:922 [inline]
__xa_clear_mark+0xf5/0x1e0 lib/xarray.c:2100
__folio_end_writeback+0xf4/0x360 mm/page-writeback.c:2948
folio_end_writeback_no_dropbehind+0x6d/0x1d0 mm/filemap.c:1661
folio_end_writeback+0x1c/0x70 mm/filemap.c:1687
ext4_finish_bio+0x459/0x8b0 fs/ext4/page-io.c:145
ext4_release_io_end+0x9f/0x1f0 fs/ext4/page-io.c:160
ext4_end_io_end+0x18d/0x240 fs/ext4/page-io.c:211
ext4_do_flush_completed_IO fs/ext4/page-io.c:291 [inline]
ext4_end_io_rsv_work+0x15b/0x1f0 fs/ext4/page-io.c:306
process_one_work kernel/workqueue.c:3275 [inline]
process_scheduled_works+0x4de/0x9e0 kernel/workqueue.c:3358
worker_thread+0x581/0x770 kernel/workqueue.c:3439
kthread+0x22a/0x280 kernel/kthread.c:467
ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888107a25228 of 8 bytes by task 3579 on cpu 1:
xas_find_chunk include/linux/xarray.h:1752 [inline]
xas_find_marked+0x213/0x620 lib/xarray.c:1510
find_get_entry mm/filemap.c:2064 [inline]
filemap_get_folios_tag+0xfa/0x510 mm/filemap.c:2332
__filemap_fdatawait_range mm/filemap.c:523 [inline]
filemap_fdatawait_keep_errors+0x6c/0x190 mm/filemap.c:626
wait_sb_inodes fs/fs-writeback.c:2805 [inline]
sync_inodes_sb+0x40e/0x4c0 fs/fs-writeback.c:2927
sync_inodes_one_sb+0x3d/0x50 fs/sync.c:77
__iterate_supers+0x110/0x220 fs/super.c:927
iterate_supers+0x1f/0x30 fs/super.c:942
ksys_sync fs/sync.c:102 [inline]
__ia32_sys_sync+0x5c/0xb0 fs/sync.c:111
x64_sys_call+0x2f3a/0x3020 arch/x86/include/generated/asm/syscalls_64.h:163
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffffffff0000 -> 0xffffffffffe00000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3579 Comm: syz.1.257 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


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