KCSAN: data-race in __ext4_update_other_inode_time / writeback_single_inode

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b3298500 Merge tag 'for-5.10/dm-fixes' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14b4e3f7500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c949fed53798f819
dashboard link: https://syzkaller.appspot.com/bug?extid=52fef5d0e9caf3a8bcf6
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+52fef5...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __ext4_update_other_inode_time / writeback_single_inode

write to 0xffff88810c2876b8 of 8 bytes by task 20239 on cpu 1:
writeback_single_inode+0x109/0x580 fs/fs-writeback.c:1567
sync_inode fs/fs-writeback.c:2606 [inline]
sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2626
ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
ext4_sync_file+0x359/0x6c0 fs/ext4/fsync.c:170
vfs_fsync_range+0x107/0x120 fs/sync.c:200
generic_write_sync include/linux/fs.h:2739 [inline]
ext4_buffered_write_iter+0x384/0x3d0 fs/ext4/file.c:278
ext4_file_write_iter+0x45e/0x1090 fs/ext4/file.c:503
call_write_iter include/linux/fs.h:1903 [inline]
new_sync_write fs/read_write.c:518 [inline]
vfs_write+0x6d4/0x7c0 fs/read_write.c:605
ksys_write+0xce/0x180 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:667
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810c2876b8 of 8 bytes by task 20237 on cpu 0:
__ext4_update_other_inode_time+0x45/0x550 fs/ext4/inode.c:4955
ext4_update_other_inodes_time fs/ext4/inode.c:5002 [inline]
ext4_do_update_inode fs/ext4/inode.c:5131 [inline]
ext4_mark_iloc_dirty+0x1286/0x1650 fs/ext4/inode.c:5712
__ext4_mark_inode_dirty+0x450/0x610 fs/ext4/inode.c:5906
__ext4_ext_dirty fs/ext4/extents.c:169 [inline]
ext4_split_extent_at+0x4f2/0xb40 fs/ext4/extents.c:3197
ext4_force_split_extent_at fs/ext4/extents.c:305 [inline]
ext4_swap_extents+0xd76/0x13a0 fs/ext4/extents.c:5664
move_extent_per_page+0xbea/0x1590 fs/ext4/move_extent.c:360
ext4_move_extents+0xab2/0xc00 fs/ext4/move_extent.c:673
__ext4_ioctl fs/ext4/ioctl.c:988 [inline]
ext4_ioctl+0x2120/0x3540 fs/ext4/ioctl.c:1319
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
__x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20237 Comm: syz-executor.0 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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