[moderation] [ext4?] KCSAN: data-race in inode_cgwb_move_to_attached / vfs_fsync_range

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bb066fe812d6 Merge tag 'pci-v6.14-fixes-2' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ee8ca4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e757e3762bd630b
dashboard link: https://syzkaller.appspot.com/bug?extid=999bb2ad2c1c78594c83
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/96c2fa324092/disk-bb066fe8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d0c48f9198dc/vmlinux-bb066fe8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9ae4ace7c1c/bzImage-bb066fe8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+999bb2...@syzkaller.appspotmail.com

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

write to 0xffff8881064ddcb8 of 4 bytes by task 18513 on cpu 1:
inode_cgwb_move_to_attached+0x9a/0x300 fs/fs-writeback.c:309
writeback_single_inode+0x2b5/0x3f0 fs/fs-writeback.c:1818
sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2871
generic_buffers_fsync_noflush+0xd8/0x120 fs/buffer.c:610
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:2958 [inline]
ext4_buffered_write_iter+0x358/0x3c0 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 0xffff8881064ddcb8 of 4 bytes by task 18526 on cpu 0:
vfs_fsync_range+0x9a/0x130 fs/sync.c:185
generic_write_sync include/linux/fs.h:2958 [inline]
ext4_buffered_write_iter+0x358/0x3c0 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: 0x00000022 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 18526 Comm: syz.0.4739 Not tainted 6.14.0-rc1-syzkaller-00081-gbb066fe812d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
==================================================================


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[syzbot]

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