[moderation] [ext4?] KCSAN: data-race in __writeback_single_inode / vfs_fsync_range (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 186f3edfdd41 Merge tag 'pinctrl-v6.17-1' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1570bcf0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b1727c1bf978fe
dashboard link: https://syzkaller.appspot.com/bug?extid=fbea47ac63f2a4eca1cc
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/cf950747c6b3/disk-186f3edf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ffbb35b7f500/vmlinux-186f3edf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/70a177ddb575/bzImage-186f3edf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fbea47...@syzkaller.appspotmail.com

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

read-write to 0xffff888106ed01a0 of 4 bytes by task 13548 on cpu 0:
__writeback_single_inode+0x1e3/0x7c0 fs/fs-writeback.c:1716
writeback_single_inode+0x167/0x3e0 fs/fs-writeback.c:1801
sync_inode_metadata+0x5b/0x90 fs/fs-writeback.c:2883
generic_buffers_fsync_noflush+0xd9/0x120 fs/buffer.c:619
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x1ab/0x690 fs/ext4/fsync.c:147
vfs_fsync_range+0x10d/0x130 fs/sync.c:187
generic_write_sync include/linux/fs.h:3042 [inline]
ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
ext4_file_write_iter+0x383/0xf00 fs/ext4/file.c:-1
iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
splice_direct_to_actor+0x30f/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+0x380/0x650 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64 fs/read_write.c:1417 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106ed01a0 of 4 bytes by task 13545 on cpu 1:
vfs_fsync_range+0x9b/0x130 fs/sync.c:185
generic_write_sync include/linux/fs.h:3042 [inline]
ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
ext4_file_write_iter+0x383/0xf00 fs/ext4/file.c:-1
iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
splice_direct_to_actor+0x30f/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+0x380/0x650 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64 fs/read_write.c:1417 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000003a -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13545 Comm: syz.2.3637 Not tainted 6.16.0-syzkaller-11241-g186f3edfdd41 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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[syzbot]

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