[moderation] [fs?] [mm?] KCSAN: data-race in __writeback_single_inode / xas_clear_mark (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ceb8bf2ceaa7 module: Convert default symbol namespace to s..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1543efc0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5337d87dae437af8
dashboard link: https://syzkaller.appspot.com/bug?extid=59105790ff8c4cde3b5f
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/911a699867ea/disk-ceb8bf2c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/db2d49fa1c14/vmlinux-ceb8bf2c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e721fa3d829a/bzImage-ceb8bf2c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+591057...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 128
==================================================================
BUG: KCSAN: data-race in __writeback_single_inode / xas_clear_mark

write to 0xffff888106b2e314 of 4 bytes by task 4381 on cpu 0:
xa_mark_clear lib/xarray.c:77 [inline]
xas_clear_mark+0x169/0x180 lib/xarray.c:925
__folio_start_writeback+0x2d9/0x430 mm/page-writeback.c:3158
__mpage_writepage+0xbed/0xe10 fs/mpage.c:619
write_cache_pages+0x62/0x100 mm/page-writeback.c:2659
mpage_writepages+0x72/0xf0 fs/mpage.c:666
fat_writepages+0x24/0x30 fs/fat/inode.c:199
do_writepages+0x1d8/0x480 mm/page-writeback.c:2702
filemap_fdatawrite_wbc mm/filemap.c:397 [inline]
__filemap_fdatawrite_range mm/filemap.c:430 [inline]
file_write_and_wait_range+0x168/0x2f0 mm/filemap.c:787
__generic_file_fsync+0x46/0x140 fs/libfs.c:1532
fat_file_fsync+0x46/0x100 fs/fat/file.c:191
vfs_fsync_range+0x116/0x130 fs/sync.c:187
generic_write_sync include/linux/fs.h:2904 [inline]
generic_file_write_iter+0x185/0x1c0 mm/filemap.c:4186
iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x398/0x660 fs/read_write.c:1363
__do_sys_sendfile64 fs/read_write.c:1424 [inline]
__se_sys_sendfile64 fs/read_write.c:1410 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106b2e314 of 4 bytes by task 4372 on cpu 1:
xa_marked include/linux/xarray.h:424 [inline]
mapping_tagged include/linux/fs.h:504 [inline]
__writeback_single_inode+0x210/0x850 fs/fs-writeback.c:1731
writeback_single_inode+0x16c/0x3f0 fs/fs-writeback.c:1801
sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2871
__generic_file_fsync+0xed/0x140 fs/libfs.c:1543
fat_file_fsync+0x46/0x100 fs/fat/file.c:191
vfs_fsync_range+0x116/0x130 fs/sync.c:187
generic_write_sync include/linux/fs.h:2904 [inline]
generic_file_write_iter+0x185/0x1c0 mm/filemap.c:4186
iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x398/0x660 fs/read_write.c:1363
__do_sys_sendfile64 fs/read_write.c:1424 [inline]
__se_sys_sendfile64 fs/read_write.c:1410 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0e000021 -> 0x00000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4372 Comm: syz.2.283 Not tainted 6.13.0-rc1-syzkaller-00005-gceb8bf2ceaa7 #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.