KCSAN: data-race in get_cpu_idle_time_us / tick_nohz_idle

KCSAN: data-race in get_cpu_idle_time_us / tick_nohz_idle_exit
Status: auto-closed as invalid on 2020/04/07 20:15
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 657d, last: 601d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in get_cpu_idle_time_us / tick_nohz_idle_exit (4)	1	331d	331d	0/22	auto-closed as invalid on 2020/11/28 02:26
upstream	KCSAN: data-race in get_cpu_idle_time_us / tick_nohz_idle_exit (2)	4	462d	489d	0/22	closed as invalid on 2020/06/18 14:13
upstream	KCSAN: data-race in get_cpu_idle_time_us / tick_nohz_idle_exit (3)	1	385d	385d	0/22	auto-closed as invalid on 2020/10/05 06:48

Sample crash report:

==================================================================
BUG: KCSAN: data-race in get_cpu_idle_time_us / tick_nohz_idle_exit

read to 0xffff88812c02010c of 1 bytes by task 26012 on cpu 1:
 get_cpu_idle_time_us+0xed/0x180 kernel/time/tick-sched.c:586
 get_idle_time.isra.0+0x6e/0xa0 fs/proc/stat.c:53
 show_stat+0x254/0xa20 fs/proc/stat.c:131
 seq_read+0x350/0x9d0 fs/seq_file.c:229
 proc_reg_read+0xe9/0x140 fs/proc/inode.c:223
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_loop_readv_writev fs/read_write.c:701 [inline]
 do_iter_read+0x357/0x3d0 fs/read_write.c:935
 vfs_readv+0x9c/0xf0 fs/read_write.c:997
 do_preadv+0x131/0x1d0 fs/read_write.c:1089
 __do_sys_preadv fs/read_write.c:1139 [inline]
 __se_sys_preadv fs/read_write.c:1134 [inline]
 __x64_sys_preadv+0x61/0x80 fs/read_write.c:1134
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812c02010c of 1 bytes by task 0 on cpu 0:
 tick_nohz_stop_idle kernel/time/tick-sched.c:547 [inline]
 tick_nohz_idle_exit+0x183/0x1e0 kernel/time/tick-sched.c:1189
 do_idle+0xb1/0x290 kernel/sched/idle.c:282
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 rest_init+0xec/0xf6 init/main.c:452
 arch_call_rest_init+0x17/0x37
 start_kernel+0x838/0x85e init/main.c:786
 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490
 x86_64_start_kernel+0x72/0x76 arch/x86/kernel/head64.c:471
 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 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-upstream-kcsan-gce	2020/01/28 20:12	https://github.com/google/ktsan.git kcsan	245a43005292	c8e81ce4	.config	log	report
ci2-upstream-kcsan-gce	2020/01/27 22:40	https://github.com/google/ktsan.git kcsan	245a43005292	56cd6c9b	.config	log	report
ci2-upstream-kcsan-gce	2019/12/03 01:02	https://github.com/google/ktsan.git kcsan	ef798c30ba4e	ab342da3	.config	log	report