KCSAN: data-race in __percpu_ref_switch_mode / percpu_ref_switch_to_atomic

KCSAN: data-race in __percpu_ref_switch_mode / percpu_ref_switch_to_atomic_rcu
Status: auto-closed as invalid on 2020/12/02 11:50
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 357d, last: 357d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __percpu_ref_switch_mode / percpu_ref_switch_to_atomic_rcu (2)				8	76d	84d	0/22	auto-closed as invalid on 2021/09/10 01:57

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __percpu_ref_switch_mode / percpu_ref_switch_to_atomic_rcu

write to 0xffff88812bcedb50 of 8 bytes by interrupt on cpu 1:
 percpu_ref_call_confirm_rcu lib/percpu-refcount.c:155 [inline]
 percpu_ref_switch_to_atomic_rcu+0x15d/0x310 lib/percpu-refcount.c:199
 rcu_do_batch kernel/rcu/tree.c:2476 [inline]
 rcu_core+0x6bb/0xbc0 kernel/rcu/tree.c:2711
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2724
 __do_softirq+0x12c/0x2b1 kernel/softirq.c:298
 run_ksoftirqd+0x13/0x20 kernel/softirq.c:653
 smpboot_thread_fn+0x34f/0x520 kernel/smpboot.c:165
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88812bcedb50 of 8 bytes by task 17873 on cpu 0:
 __percpu_ref_switch_mode+0xc9/0x390 lib/percpu-refcount.c:269
 percpu_ref_resurrect+0xba/0x110 lib/percpu-refcount.c:467
 __io_uring_register fs/io_uring.c:9549 [inline]
 __do_sys_io_uring_register+0x875/0x2ab0 fs/io_uring.c:9667
 __se_sys_io_uring_register fs/io_uring.c:9649 [inline]
 __x64_sys_io_uring_register+0x4f/0x60 fs/io_uring.c:9649
 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: 17873 Comm: syz-executor.4 Not tainted 5.10.0-rc1-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	2020/10/28 11:40	upstream	ed8780e3f2ec	96e03c1c	.config	log	report			info