[moderation] [ext4?] KCSAN: data-race in __writeback_single_inode / generic_buffers_fsync_noflush (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5437f30d3458 Merge tag '6.11-rc-smb-client-fixes-part2' of..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14bd2fad980000
kernel config: https://syzkaller.appspot.com/x/.config?x=7398409c79c30d03
dashboard link: https://syzkaller.appspot.com/bug?extid=00d3e3caaad4a50203c2
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/24365c0ec819/disk-5437f30d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/04124536addf/vmlinux-5437f30d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/66b3640c1a90/bzImage-5437f30d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00d3e3...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 1024
==================================================================
BUG: KCSAN: data-race in __writeback_single_inode / generic_buffers_fsync_noflush

read-write to 0xffff888106a66a80 of 8 bytes by task 11160 on cpu 0:
__writeback_single_inode+0x201/0x870 fs/fs-writeback.c:1687
writeback_single_inode+0x12f/0x4a0 fs/fs-writeback.c:1772
sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2842
generic_buffers_fsync_noflush+0xe4/0x130 fs/buffer.c:610
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:2816 [inline]
ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
ext4_file_write_iter+0x29f/0xe30
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+0x3ab/0x950 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+0xfc3/0x2e00 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 0xffff888106a66a80 of 8 bytes by task 11144 on cpu 1:
generic_buffers_fsync_noflush+0x89/0x130 fs/buffer.c:605
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:2816 [inline]
ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
ext4_file_write_iter+0x29f/0xe30
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+0x3ab/0x950 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+0xfc3/0x2e00 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: 0x0000000000000084 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11144 Comm: syz.0.2295 Not tainted 6.10.0-syzkaller-12888-g5437f30d3458 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
==================================================================


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