syzbot


WARNING: suspicious RCU usage in gc_worker

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: 3066820034b5 rcu: Reject RCU_LOCKDEP_WARN() false positives
First crash: 633d, last: 606d

Sample crash report:
=============================
WARNING: suspicious RCU usage
5.13.0-rc5-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8304 Illegal context switch in RCU-bh read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
2 locks held by kworker/1:1/9183:
 #0: 
ffff888011065d38
 (
(wq_completion)events_power_efficient
){+.+.}-{0:0}
, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
, at: set_work_data kernel/workqueue.c:617 [inline]
, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2247
 #1: 
ffffc900019afda8
 (
(work_completion)(&(&gc_work->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2251

stack backtrace:
CPU: 1 PID: 9183 Comm: kworker/1:1 Not tainted 5.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient gc_worker
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep+0x229/0x2c0 kernel/sched/core.c:8304
 gc_worker+0x4eb/0xef0 net/netfilter/nf_conntrack_core.c:1431
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
 kthread+0x3b1/0x4a0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci-upstream-kasan-gce 2021/06/08 16:59 upstream 614124bea77e b718257f .config console log report info WARNING: suspicious RCU usage in gc_worker
ci-upstream-kasan-gce 2021/05/21 19:41 upstream 79a106fc6585 3c7fef33 .config console log report info WARNING: suspicious RCU usage in gc_worker
ci-upstream-kasan-gce-selinux-root 2021/05/13 03:57 upstream dbb5afad100a ed7d41c5 .config console log report info WARNING: suspicious RCU usage in gc_worker
* Struck through repros no longer work on HEAD.