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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dccb07f2914c Merge tag 'for-6.9-rc7-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15507ab8980000
kernel config: https://syzkaller.appspot.com/x/.config?x=168fab99759dff68
dashboard link: https://syzkaller.appspot.com/bug?extid=40d7ce09fc0205cdd588
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/3c2d87fc08e4/disk-dccb07f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2722c4f79b5b/vmlinux-dccb07f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b652f5cb7bf8/bzImage-dccb07f2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+40d7ce...@syzkaller.appspotmail.com

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

write to 0xffff88810827304c of 4 bytes by task 11752 on cpu 0:
xa_mark_set lib/xarray.c:71 [inline]
xas_set_mark+0x131/0x150 lib/xarray.c:892
__folio_start_writeback+0x1f1/0x450 mm/page-writeback.c:3061
ext4_bio_write_folio+0x592/0x9a0 fs/ext4/page-io.c:557
mpage_submit_folio fs/ext4/inode.c:1869 [inline]
mpage_process_page_bufs+0x488/0x5d0 fs/ext4/inode.c:1982
mpage_prepare_extent_to_map+0x788/0xb80 fs/ext4/inode.c:2490
ext4_do_writepages+0xa20/0x2110 fs/ext4/inode.c:2677
ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2768
do_writepages+0x1d8/0x480 mm/page-writeback.c:2612
filemap_fdatawrite_wbc+0xdb/0x100 mm/filemap.c:397
__filemap_fdatawrite_range mm/filemap.c:430 [inline]
file_write_and_wait_range+0xc8/0x170 mm/filemap.c:788
generic_buffers_fsync_noflush+0x4c/0x130 fs/buffer.c:602
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x20b/0x6c0 fs/ext4/fsync.c:151
vfs_fsync_range+0x122/0x140 fs/sync.c:188
generic_write_sync include/linux/fs.h:2795 [inline]
ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
ext4_file_write_iter+0x29f/0xe30
call_write_iter include/linux/fs.h:2110 [inline]
iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x3b9/0x970 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
x64_sys_call+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810827304c of 4 bytes by task 11763 on cpu 1:
xa_marked include/linux/xarray.h:420 [inline]
mapping_tagged include/linux/fs.h:500 [inline]
__writeback_single_inode+0x21d/0x870 fs/fs-writeback.c:1701
writeback_single_inode+0x12f/0x4a0 fs/fs-writeback.c:1771
sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2833
generic_buffers_fsync_noflush+0xe4/0x130 fs/buffer.c:612
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x20b/0x6c0 fs/ext4/fsync.c:151
vfs_fsync_range+0x122/0x140 fs/sync.c:188
generic_write_sync include/linux/fs.h:2795 [inline]
ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
ext4_file_write_iter+0x29f/0xe30
call_write_iter include/linux/fs.h:2110 [inline]
iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x3b9/0x970 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
x64_sys_call+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x05000021 -> 0x00000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11763 Comm: syz-executor.1 Tainted: G W 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup