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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7af08b57bcb9 Merge tag 'trace-v6.13-2' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=103509e8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=77174711582263a3
dashboard link: https://syzkaller.appspot.com/bug?extid=19e0b8c172d4557d7acf
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/13ed5c4111d5/disk-7af08b57.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b14531c093bd/vmlinux-7af08b57.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0ddfac565b6b/bzImage-7af08b57.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+19e0b8...@syzkaller.appspotmail.com

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

read-write to 0xffff88810668ea38 of 4 bytes by task 13291 on cpu 0:
redirty_tail_locked+0x54/0x270 fs/fs-writeback.c:1373
writeback_single_inode+0x221/0x3f0 fs/fs-writeback.c:1821
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:2904 [inline]
ext4_buffered_write_iter+0x326/0x370 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 0xffff88810668ea38 of 4 bytes by task 13300 on cpu 1:
vfs_fsync_range+0x9a/0x130 fs/sync.c:185
generic_write_sync include/linux/fs.h:2904 [inline]
ext4_buffered_write_iter+0x326/0x370 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: 0x0000003a -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13300 Comm: syz.3.2647 Tainted: G W 6.12.0-syzkaller-10689-g7af08b57bcb9 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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