[moderation] [mm?] [fs?] KCSAN: data-race in file_write_and_wait_range / xas_set_mark (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 23acd177540d Merge tag 'vfs-6.13.ecryptfs' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16a81ac0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=44f4147e19698730
dashboard link: https://syzkaller.appspot.com/bug?extid=cb409795b9a50c807ea2
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/a063bc39960c/disk-23acd177.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/47727532d600/vmlinux-23acd177.xz
kernel image: https://storage.googleapis.com/syzbot-assets/99056cf62ce2/bzImage-23acd177.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cb4097...@syzkaller.appspotmail.com

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

write to 0xffff8881062cd024 of 4 bytes by task 6436 on cpu 1:
xa_mark_set lib/xarray.c:71 [inline]
xas_set_mark+0x131/0x150 lib/xarray.c:893
tag_pages_for_writeback+0xa5/0x2a0 mm/page-writeback.c:2420
ext4_do_writepages+0x694/0x2130 fs/ext4/inode.c:2660
ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2813
do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
filemap_fdatawrite_wbc mm/filemap.c:398 [inline]
__filemap_fdatawrite_range mm/filemap.c:431 [inline]
file_write_and_wait_range+0x168/0x2f0 mm/filemap.c:788
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:188
generic_write_sync include/linux/fs.h:2894 [inline]
ext4_buffered_write_iter+0x326/0x370 fs/ext4/file.c:305
ext4_file_write_iter+0x360/0xf20
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+0x39b/0x970 fs/read_write.c:1388
__do_sys_sendfile64 fs/read_write.c:1455 [inline]
__se_sys_sendfile64 fs/read_write.c:1441 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
x64_sys_call+0xed5/0x2d60 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 0xffff8881062cd024 of 4 bytes by task 6454 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:394 [inline]
__filemap_fdatawrite_range mm/filemap.c:431 [inline]
file_write_and_wait_range+0x116/0x2f0 mm/filemap.c:788
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:188
generic_write_sync include/linux/fs.h:2894 [inline]
ext4_buffered_write_iter+0x326/0x370 fs/ext4/file.c:305
ext4_file_write_iter+0x360/0xf20
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+0x39b/0x970 fs/read_write.c:1388
__do_sys_sendfile64 fs/read_write.c:1455 [inline]
__se_sys_sendfile64 fs/read_write.c:1441 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
x64_sys_call+0xed5/0x2d60 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: 0x02000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6454 Comm: syz.0.720 Not tainted 6.12.0-syzkaller-00171-g23acd177540d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
==================================================================


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