KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_idle_stop_tick (3)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 766d004d mm, kcsan: Instrument SLAB free with ASSERT_EXCLU..
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=135bd529e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b313b4492ea15bae
dashboard link: https://syzkaller.appspot.com/bug?extid=2ccfc33f51d6a1928594
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [fwei...@gmail.com linux-...@vger.kernel.org mi...@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+2ccfc3...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_idle_stop_tick

write to 0xffffffff85d05610 of 4 bytes by task 0 on cpu 1:
tick_nohz_stop_tick kernel/time/tick-sched.c:775 [inline]
__tick_nohz_idle_stop_tick kernel/time/tick-sched.c:967 [inline]
tick_nohz_idle_stop_tick+0x52c/0x680 kernel/time/tick-sched.c:988
cpuidle_idle_call kernel/sched/idle.c:151 [inline]
do_idle+0x1ad/0x290 kernel/sched/idle.c:269
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
start_secondary+0x164/0x1b0 arch/x86/kernel/smpboot.c:264
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

read to 0xffffffff85d05610 of 4 bytes by task 0 on cpu 0:
tick_nohz_stop_tick kernel/time/tick-sched.c:774 [inline]
__tick_nohz_idle_stop_tick kernel/time/tick-sched.c:967 [inline]
tick_nohz_idle_stop_tick+0x191/0x680 kernel/time/tick-sched.c:988
cpuidle_idle_call kernel/sched/idle.c:151 [inline]
do_idle+0x1ad/0x290 kernel/sched/idle.c:269
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
rest_init+0xe4/0xeb init/main.c:632
arch_call_rest_init+0x13/0x2b
start_kernel+0xcc2/0xceb init/main.c:971
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 0 Comm: swapper/0 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.