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 (3)
Status: auto-closed as invalid on 2020/10/05 06:48
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 386d, last: 386d

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	333d	333d	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	463d	490d	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	602d	659d	0/22	auto-closed as invalid on 2020/04/07 20:15

Sample crash report:

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

write to 0xffff88812c01f17c of 1 bytes by task 0 on cpu 0:
 tick_nohz_idle_exit+0xcb/0x290 kernel/time/tick-sched.c:1199
 do_idle+0x280/0x2c0 kernel/sched/idle.c:286
 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:369
 rest_init+0xd8/0xe0 init/main.c:708
 arch_call_rest_init+0xa/0xb
 start_kernel+0x608/0x6d0 init/main.c:1048
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

read to 0xffff88812c01f17c of 1 bytes by task 19811 on cpu 1:
 get_cpu_idle_time_us+0x6b/0x1f0 kernel/time/tick-sched.c:599
 get_idle_time fs/proc/stat.c:53 [inline]
 show_stat+0x7ff/0xd10 fs/proc/stat.c:172
 seq_read+0x2ee/0x900 fs/seq_file.c:208
 pde_read fs/proc/inode.c:306 [inline]
 proc_reg_read+0xde/0x1a0 fs/proc/inode.c:316
 do_loop_readv_writev fs/read_write.c:734 [inline]
 do_iter_read+0x3d2/0x4b0 fs/read_write.c:955
 vfs_readv fs/read_write.c:1073 [inline]
 do_preadv+0x13b/0x230 fs/read_write.c:1165
 __do_sys_preadv fs/read_write.c:1215 [inline]
 __se_sys_preadv fs/read_write.c:1210 [inline]
 __x64_sys_preadv+0x54/0x60 fs/read_write.c:1210
 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: 1 PID: 19811 Comm: syz-executor.0 Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/08/31 06:47	upstream	dcc5c6f013d8	d5a3ae1f	.config	log	report