KCSAN: data-race in generic_fillattr / shmem_unlink (2)

[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=12312d9e100000
kernel config: https://syzkaller.appspot.com/x/.config?x=ff291dc25f22cdda
dashboard link: https://syzkaller.appspot.com/bug?extid=c7b308c1b99381b097f1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [ak...@linux-foundation.org hu...@google.com linux-...@vger.kernel.org linu...@kvack.org]

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+c7b308...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in generic_fillattr / shmem_unlink

write to 0xffff888124c34970 of 8 bytes by task 14231 on cpu 0:
shmem_unlink+0xa2/0x150 mm/shmem.c:2981
shmem_rename2+0x10f/0x4a0 mm/shmem.c:3075
vfs_rename+0x8f8/0x1130 fs/namei.c:4287
do_renameat2+0x9e8/0xa50 fs/namei.c:4437
__do_sys_rename fs/namei.c:4483 [inline]
__se_sys_rename fs/namei.c:4481 [inline]
__x64_sys_rename+0x44/0x60 fs/namei.c:4481
do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888124c34970 of 8 bytes by task 14090 on cpu 1:
generic_fillattr+0xf5/0x1e0 fs/stat.c:44
vfs_getattr_nosec+0x155/0x160 fs/stat.c:86
vfs_getattr+0x53/0x70 fs/stat.c:120
vfs_statx+0x104/0x190 fs/stat.c:201
vfs_stat include/linux/fs.h:3279 [inline]
__do_sys_newstat+0x50/0xb0 fs/stat.c:351
__se_sys_newstat fs/stat.c:347 [inline]
__x64_sys_newstat+0x37/0x50 fs/stat.c:347
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: 1 PID: 14090 Comm: systemd-udevd Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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