bisecting fixing commit since 78d697fc93f98054e36a3ab76dca1a88802ba7be building syzkaller on 4a4e0509de520c7139ca2b5606712cbadc550db2 testing commit 78d697fc93f98054e36a3ab76dca1a88802ba7be with gcc (GCC) 8.1.0 kernel signature: d05c3145c5af485032fc27d4e0b8790d9e36b2de3bde1b56ba9a7431890962a2 all runs: crashed: WARNING: suspicious RCU usage in nf_reinject testing current HEAD 4f68020fef1c6cf1b680ffb6481ac41379283ea3 testing commit 4f68020fef1c6cf1b680ffb6481ac41379283ea3 with gcc (GCC) 8.1.0 kernel signature: 3dbae0d5b279904b089188be3d49e52676bb6f39bbb6ae0860b20377ec061bf5 all runs: crashed: WARNING: suspicious RCU usage in nf_reinject revisions tested: 2, total time: 26m0.95068013s (build: 18m21.726163114s, test: 6m38.466521523s) the crash still happens on HEAD commit msg: Linux 4.14.182 crash: WARNING: suspicious RCU usage in nf_reinject ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ============================= WARNING: suspicious RCU usage 4.14.182-syzkaller #0 Not tainted ----------------------------- net/netfilter/nf_queue.c:227 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by ksoftirqd/0/7: #0: (rcu_callback){....}, at: [] __rcu_reclaim kernel/rcu/rcu.h:185 [inline] #0: (rcu_callback){....}, at: [] rcu_do_batch kernel/rcu/tree.c:2699 [inline] #0: (rcu_callback){....}, at: [] invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline] #0: (rcu_callback){....}, at: [] __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline] #0: (rcu_callback){....}, at: [] rcu_process_callbacks+0x8be/0x11e0 kernel/rcu/tree.c:2946 #1: (&(&inst->lock)->rlock){+.-.}, at: [] spin_lock_bh include/linux/spinlock.h:322 [inline] #1: (&(&inst->lock)->rlock){+.-.}, at: [] nfqnl_flush+0x2f/0x270 net/netfilter/nfnetlink_queue.c:232 stack backtrace: CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.14.182-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 lockdep_rcu_suspicious+0x14a/0x153 kernel/locking/lockdep.c:4669 nf_reinject+0x4e4/0x680 net/netfilter/nf_queue.c:227 nfqnl_flush+0x18d/0x270 net/netfilter/nfnetlink_queue.c:237 instance_destroy_rcu+0x15/0x30 net/netfilter/nfnetlink_queue.c:171 __rcu_reclaim kernel/rcu/rcu.h:195 [inline] rcu_do_batch kernel/rcu/tree.c:2699 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline] rcu_process_callbacks+0x7e0/0x11e0 kernel/rcu/tree.c:2946 __do_softirq+0x246/0x9b0 kernel/softirq.c:288 run_ksoftirqd+0x92/0x1a0 kernel/softirq.c:670 smpboot_thread_fn+0x553/0x850 kernel/smpboot.c:164 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 net_ratelimit: 1112 callbacks suppressed ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table net_ratelimit: 1080 callbacks suppressed ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table ip_tables: iptables: counters copy to user failed while replacing table