KCSAN: data-race in generic_fillattr / shmem_rename2 (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 40959e34 kcsan: Avoid blocking producers in prepare_report()
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=176630afe00000
kernel config: https://syzkaller.appspot.com/x/.config?x=1ab2c758651b11f6
dashboard link: https://syzkaller.appspot.com/bug?extid=74c377be87ce8ee28edd
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+74c377...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in generic_fillattr / shmem_rename2

read to 0xffff888126af89f0 of 16 bytes by task 7767 on cpu 1:
generic_fillattr+0x145/0x1e0 fs/stat.c:46
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:3271 [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+0xc7/0x390 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888126af89f0 of 16 bytes by task 7956 on cpu 0:
shmem_rename2+0x1df/0x4a0 mm/shmem.c:3092
vfs_rename+0x87d/0x10b0 fs/namei.c:4551
do_renameat2+0x9e8/0xa50 fs/namei.c:4701
__do_sys_rename fs/namei.c:4747 [inline]
__se_sys_rename fs/namei.c:4745 [inline]
__x64_sys_rename+0x44/0x60 fs/namei.c:4745
do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7956 Comm: udevd Not tainted 5.6.0-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.