KCSAN: data-race in ktime_get_real_seconds / timekeeping_advance (3)

[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=1466cd71e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4b9db179318d21f
dashboard link: https://syzkaller.appspot.com/bug?extid=bb0ddd145ff92d58046c
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [john....@linaro.org linux-...@vger.kernel.org
sb...@kernel.org tg...@linutronix.de 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+bb0ddd...@syzkaller.appspotmail.com

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

write to 0xffffffff8624b2c8 of 280 bytes by interrupt on cpu 0:
timekeeping_advance+0x88e/0xd80 include/linux/string.h:380
update_wall_time+0x19/0x20 kernel/time/timekeeping.c:2137
tick_do_update_jiffies64+0x1a4/0x250 kernel/time/tick-sched.c:94
tick_sched_do_timer+0xd4/0xe0 kernel/time/tick-sched.c:138
tick_sched_timer+0x43/0xe0 kernel/time/tick-sched.c:1303
__run_hrtimer kernel/time/hrtimer.c:1517 [inline]
__hrtimer_run_queues+0x274/0x5f0 kernel/time/hrtimer.c:1579
hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1641
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
__sanitizer_cov_trace_switch+0x49/0x80 kernel/kcov.c:310
__read_once_size+0x25/0xe0 include/linux/compiler.h:232
PageTail include/linux/page-flags.h:183 [inline]
PageCompound include/linux/page-flags.h:188 [inline]
page_mapcount include/linux/mm.h:706 [inline]
zap_pte_range mm/memory.c:1081 [inline]
zap_pmd_range mm/memory.c:1184 [inline]
zap_pud_range mm/memory.c:1213 [inline]
zap_p4d_range mm/memory.c:1234 [inline]
unmap_page_range+0x1353/0x1940 mm/memory.c:1255
unmap_single_vma+0x144/0x200 mm/memory.c:1300
unmap_vmas+0xda/0x1a0 mm/memory.c:1332
exit_mmap+0x13e/0x300 mm/mmap.c:3140
__mmput kernel/fork.c:1082 [inline]
mmput+0xea/0x280 kernel/fork.c:1103
exit_mm kernel/exit.c:485 [inline]
do_exit+0x4ac/0x18c0 kernel/exit.c:784
do_group_exit+0xb4/0x1c0 kernel/exit.c:895
__do_sys_exit_group kernel/exit.c:906 [inline]
__se_sys_exit_group kernel/exit.c:904 [inline]
__x64_sys_exit_group+0x2e/0x30 kernel/exit.c:904
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff8624b338 of 8 bytes by task 15246 on cpu 1:
ktime_get_real_seconds+0x20/0x40 kernel/time/timekeeping.c:127
recently_deleted fs/ext4/ialloc.c:694 [inline]
find_inode_bit.isra.0+0x1e2/0x300 fs/ext4/ialloc.c:717
__ext4_new_inode+0xd45/0x2f10 fs/ext4/ialloc.c:909
ext4_symlink+0x31c/0x9b0 fs/ext4/namei.c:3275
vfs_symlink fs/namei.c:4131 [inline]
vfs_symlink+0x218/0x310 fs/namei.c:4117
do_symlinkat+0x1a5/0x1e0 fs/namei.c:4158
__do_sys_symlink fs/namei.c:4177 [inline]
__se_sys_symlink fs/namei.c:4175 [inline]
__x64_sys_symlink+0x3f/0x50 fs/namei.c:4175
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: 15246 Comm: syz-executor.0 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.