KCSAN: data-race in inode_owner_or_capable / ovl_write_iter

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 245a4300 Merge branch 'rcu/kcsan' into tip/locking/kcsan
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=13eef735e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4b9db179318d21f
dashboard link: https://syzkaller.appspot.com/bug?extid=14b4ad8e3072bf5b6a4e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk 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+14b4ad...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in inode_owner_or_capable / ovl_write_iter

read to 0xffff888128e7aac4 of 4 bytes by task 23474 on cpu 0:
inode_owner_or_capable+0x5c/0x100 fs/inode.c:2075
ovl_ioctl_set_flags+0x53/0x240 fs/overlayfs/file.c:416
ovl_ioctl_set_fsflags fs/overlayfs/file.c:472 [inline]
ovl_ioctl+0x121/0x2a0 fs/overlayfs/file.c:516
vfs_ioctl fs/ioctl.c:47 [inline]
file_ioctl fs/ioctl.c:545 [inline]
do_vfs_ioctl+0x84f/0xcf0 fs/ioctl.c:732
ksys_ioctl+0xbd/0xe0 fs/ioctl.c:749
__do_sys_ioctl fs/ioctl.c:756 [inline]
__se_sys_ioctl fs/ioctl.c:754 [inline]
__x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:754
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888128e7aac4 of 4 bytes by task 23456 on cpu 1:
ovl_copyattr fs/overlayfs/overlayfs.h:383 [inline]
ovl_write_iter+0x3d5/0x550 fs/overlayfs/file.c:284
call_write_iter include/linux/fs.h:1902 [inline]
new_sync_write+0x388/0x4a0 fs/read_write.c:483
__vfs_write+0xb1/0xc0 fs/read_write.c:496
__kernel_write+0xb8/0x240 fs/read_write.c:515
write_pipe_buf+0xb6/0xf0 fs/splice.c:809
splice_from_pipe_feed fs/splice.c:512 [inline]
__splice_from_pipe+0x295/0x4a0 fs/splice.c:636
splice_from_pipe+0xbb/0x100 fs/splice.c:671
default_file_splice_write+0x45/0x90 fs/splice.c:821
do_splice_from fs/splice.c:863 [inline]
direct_splice_actor+0xa0/0xc0 fs/splice.c:1037
splice_direct_to_actor+0x22b/0x540 fs/splice.c:992
do_splice_direct+0x161/0x1e0 fs/splice.c:1080
do_sendfile+0x384/0x7f0 fs/read_write.c:1464
__do_sys_sendfile64 fs/read_write.c:1519 [inline]
__se_sys_sendfile64 fs/read_write.c:1511 [inline]
__x64_sys_sendfile64+0xbe/0x140 fs/read_write.c:1511
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23456 Comm: syz-executor.2 Not tainted 5.5.0-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.