[moderation] [fs?] [mm?] KCSAN: data-race in file_write_and_wait_range / xas_clear_mark

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fc033cf25e61 Linux 6.13-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b0aac4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5e179f449c1ff36
dashboard link: https://syzkaller.appspot.com/bug?extid=4c346ec095996f236a27
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/3bd50a060c12/disk-fc033cf2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eafcbf349907/vmlinux-fc033cf2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/10046e750749/bzImage-fc033cf2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4c346e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in file_write_and_wait_range / xas_clear_mark

write to 0xffff888104bb7424 of 4 bytes by task 3543 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
ext4_bio_write_folio+0x591/0x9d0 fs/ext4/page-io.c:556
mpage_submit_folio fs/ext4/inode.c:1932 [inline]
mpage_process_page_bufs+0x486/0x5d0 fs/ext4/inode.c:2045
mpage_prepare_extent_to_map+0x788/0xb80 fs/ext4/inode.c:2546
ext4_do_writepages+0xa20/0x2130 fs/ext4/inode.c:2733
ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2824
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_buffers_fsync_noflush+0x46/0x120 fs/buffer.c:600
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x1ff/0x6c0 fs/ext4/fsync.c:151
vfs_fsync_range+0x116/0x130 fs/sync.c:187
generic_write_sync include/linux/fs.h:2904 [inline]
ext4_buffered_write_iter+0x326/0x370 fs/ext4/file.c:305
ext4_file_write_iter+0x383/0xf20
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 0xffff888104bb7424 of 4 bytes by task 3525 on cpu 1:
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]
file_write_and_wait_range+0x116/0x2f0 mm/filemap.c:787
generic_buffers_fsync_noflush+0x46/0x120 fs/buffer.c:600
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x1ff/0x6c0 fs/ext4/fsync.c:151
vfs_fsync_range+0x116/0x130 fs/sync.c:187
generic_write_sync include/linux/fs.h:2904 [inline]
ext4_buffered_write_iter+0x326/0x370 fs/ext4/file.c:305
ext4_file_write_iter+0x383/0xf20
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 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3525 Comm: syz.2.35 Not tainted 6.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================
EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.


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[syzbot]

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