KCSAN: data-race in do_settimeofday64 / ktime_get_real_seconds (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4df91062 mm: memcg: relayout structure mem_cgroup to avoid..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1655088d500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=e5abc53c8a8988263acc
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [john....@linaro.org linux-...@vger.kernel.org sb...@kernel.org tg...@linutronix.de]

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+e5abc5...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_settimeofday64 / ktime_get_real_seconds

write to 0xffffffff882f98f8 of 8 bytes by task 11634 on cpu 1:
tk_set_xtime kernel/time/timekeeping.c:138 [inline]
do_settimeofday64+0x3cb/0x550 kernel/time/timekeeping.c:1323
do_sys_settimeofday64+0x17b/0x1a0 kernel/time/time.c:195
posix_clock_realtime_set+0x13/0x20 kernel/time/posix-timers.c:185
__do_sys_clock_settime kernel/time/posix-timers.c:1079 [inline]
__se_sys_clock_settime kernel/time/posix-timers.c:1067 [inline]
__x64_sys_clock_settime+0x136/0x160 kernel/time/posix-timers.c:1067
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff882f98f8 of 8 bytes by task 11629 on cpu 0:
ktime_get_real_seconds+0x11/0x20 kernel/time/timekeeping.c:1013
recently_deleted fs/ext4/ialloc.c:703 [inline]
find_inode_bit+0x231/0x3a0 fs/ext4/ialloc.c:728
__ext4_new_inode+0xd22/0x3060 fs/ext4/ialloc.c:1062
ext4_symlink+0x2bc/0x770 fs/ext4/namei.c:3336
vfs_symlink+0x216/0x2d0 fs/namei.c:3960
do_symlinkat+0xee/0x280 fs/namei.c:3987
__do_sys_symlink fs/namei.c:4006 [inline]
__se_sys_symlink fs/namei.c:4004 [inline]
__x64_sys_symlink+0x32/0x40 fs/namei.c:4004
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: 11629 Comm: syz-executor.3 Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This report 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 issue. 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.