[moderation] [ext4?] KCSAN: data-race in move_expired_inodes / vfs_fsync_range (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3c21441eeffc Merge tag 'acpi-6.15-rc7' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1632ef68580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7bf27d52ff5e6b29
dashboard link: https://syzkaller.appspot.com/bug?extid=1b2ee3e003fddf78864b
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e2c5d926a53a/disk-3c21441e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/52058ebba6c7/vmlinux-3c21441e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90cf2d1c9e3b/bzImage-3c21441e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1b2ee3...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in move_expired_inodes / vfs_fsync_range

read-write to 0xffff888117b24a98 of 4 bytes by task 31 on cpu 1:
move_expired_inodes+0x17a/0x400 fs/fs-writeback.c:1457
queue_io+0xd9/0x2c0 fs/fs-writeback.c:1509
wb_writeback+0x226/0x5c0 fs/fs-writeback.c:2152
wb_check_start_all fs/fs-writeback.c:2284 [inline]
wb_do_writeback fs/fs-writeback.c:2310 [inline]
wb_workfn+0x4c9/0x910 fs/fs-writeback.c:2343
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x489/0x510 kernel/kthread.c:464
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888117b24a98 of 4 bytes by task 31547 on cpu 0:
vfs_fsync_range+0x9b/0x130 fs/sync.c:185
generic_write_sync include/linux/fs.h:2976 [inline]
ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
ext4_dio_write_iter fs/ext4/file.c:608 [inline]
ext4_file_write_iter+0xdbf/0xf00 fs/ext4/file.c:716
iter_file_splice_write+0x5ef/0x970 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x156/0x2a0 fs/splice.c:1158
splice_direct_to_actor+0x312/0x680 fs/splice.c:1102
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0xda/0x150 fs/splice.c:1227
do_sendfile+0x380/0x640 fs/read_write.c:1368
__do_sys_sendfile64 fs/read_write.c:1429 [inline]
__se_sys_sendfile64 fs/read_write.c:1415 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1415
x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000020 -> 0x00010022

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 31547 Comm: syz.2.3883 Not tainted 6.15.0-rc6-syzkaller-00208-g3c21441eeffc #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================


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[syzbot]

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