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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d74da846046a Merge tag 'platform-drivers-x86-v6.11-3' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15adecd5980000
kernel config: https://syzkaller.appspot.com/x/.config?x=31ece081c16313f0
dashboard link: https://syzkaller.appspot.com/bug?extid=d099d64b590847b7259f
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/ba00028307d7/disk-d74da846.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c20a2331814b/vmlinux-d74da846.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dee1fe598037/bzImage-d74da846.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d099d6...@syzkaller.appspotmail.com

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

write to 0xffff88810626c1b8 of 8 bytes by task 5088 on cpu 0:
inode_cgwb_move_to_attached+0x9b/0x300 fs/fs-writeback.c:310
writeback_single_inode+0x395/0x4a0 fs/fs-writeback.c:1789
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+0xed5/0x2d60 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 0xffff88810626c1b8 of 8 bytes by task 5093 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+0xed5/0x2d60 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: 0x0000000000000080 -> 0x0000000000000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5093 Comm: syz.1.597 Not tainted 6.11.0-rc3-syzkaller-00007-gd74da846046a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
==================================================================


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