KCSAN: data-race in __mark_inode_dirty / other_inode_match

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 7c3cd68e Merge remote-tracking branch 'linux-rcu/kcsan' in..
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=17e5ca17e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=312e39c74fd784a1
dashboard link: https://syzkaller.appspot.com/bug?extid=a1764e003e75d60d4dd3
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu el...@google.com]

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a1764e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __mark_inode_dirty / other_inode_match

write to 0xffff88811d123880 of 8 bytes by task 21411 on cpu 1:
other_inode_match fs/ext4/inode.c:4884 [inline]
other_inode_match+0x13f/0x570 fs/ext4/inode.c:4868
find_inode_nowait+0x12f/0x160 fs/inode.c:1446
ext4_update_other_inodes_time fs/ext4/inode.c:4923 [inline]
ext4_do_update_inode fs/ext4/inode.c:5049 [inline]
ext4_mark_iloc_dirty+0x12ad/0x1580 fs/ext4/inode.c:5603
ext4_mark_inode_dirty+0xe6/0x420 fs/ext4/inode.c:5796
ext4_da_write_end+0x600/0x690 fs/ext4/inode.c:3080
generic_perform_write+0x1d7/0x320 mm/filemap.c:3313
ext4_buffered_write_iter+0x14e/0x280 fs/ext4/file.c:270
ext4_file_write_iter+0xf4/0xd30 fs/ext4/file.c:642
call_write_iter include/linux/fs.h:1907 [inline]
do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:694
do_iter_write fs/read_write.c:999 [inline]
do_iter_write+0x137/0x3a0 fs/read_write.c:980
vfs_iter_write+0x56/0x80 fs/read_write.c:1040
iter_file_splice_write+0x530/0x830 fs/splice.c:760
do_splice_from fs/splice.c:863 [inline]
direct_splice_actor+0x97/0xb0 fs/splice.c:1037
splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
do_splice_direct+0x152/0x1d0 fs/splice.c:1080
do_sendfile+0x380/0x800 fs/read_write.c:1521
__do_sys_sendfile64 fs/read_write.c:1576 [inline]
__se_sys_sendfile64 fs/read_write.c:1568 [inline]
__x64_sys_sendfile64+0xb8/0x140 fs/read_write.c:1568
do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811d123880 of 8 bytes by task 21416 on cpu 0:
__mark_inode_dirty+0xb6/0x940 fs/fs-writeback.c:2272
generic_update_time+0x184/0x270 fs/inode.c:1682
update_time+0x7d/0x90 fs/inode.c:1695
file_update_time+0x205/0x2d0 fs/inode.c:1910
file_modified fs/inode.c:1933 [inline]
file_modified+0x60/0x80 fs/inode.c:1918
ext4_write_checks+0x4a/0x70 fs/ext4/file.c:249
ext4_buffered_write_iter+0x87/0x280 fs/ext4/file.c:265
ext4_file_write_iter+0xf4/0xd30 fs/ext4/file.c:642
call_write_iter include/linux/fs.h:1907 [inline]
do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:694
do_iter_write fs/read_write.c:999 [inline]
do_iter_write+0x137/0x3a0 fs/read_write.c:980
vfs_iter_write+0x56/0x80 fs/read_write.c:1040
iter_file_splice_write+0x530/0x830 fs/splice.c:760
do_splice_from fs/splice.c:863 [inline]
direct_splice_actor+0x97/0xb0 fs/splice.c:1037
splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
do_splice_direct+0x152/0x1d0 fs/splice.c:1080
do_sendfile+0x380/0x800 fs/read_write.c:1521
__do_sys_sendfile64 fs/read_write.c:1576 [inline]
__se_sys_sendfile64 fs/read_write.c:1568 [inline]
__x64_sys_sendfile64+0xb8/0x140 fs/read_write.c:1568
do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21416 Comm: syz-executor.1 Not tainted 5.7.0-rc1-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.