bisecting fixing commit since 7ae77150d94d3b535c7b85e6b3647113095e79bf building syzkaller on 54566aff1679fc74487d3efb9f7bbfbc21beed4b testing commit 7ae77150d94d3b535c7b85e6b3647113095e79bf with gcc (GCC) 8.1.0 kernel signature: 8da886e7771f3b5ba4eb8920eae227897d13ab879e9728472d63a475281a4de0 all runs: crashed: WARNING: suspicious RCU usage in ctrl_cmd_new_lookup testing current HEAD 92ed301919932f777713b9172e525674157e983d testing commit 92ed301919932f777713b9172e525674157e983d with gcc (GCC) 8.1.0 kernel signature: 6a78311a58b62f52fdc1a1595b9cfe7117acd31f8883225d527dcc9670f4ba0b all runs: crashed: WARNING: suspicious RCU usage in ctrl_cmd_new_lookup revisions tested: 2, total time: 19m4.284337782s (build: 11m13.550366533s, test: 7m14.828834455s) the crash still happens on HEAD commit msg: Linux 5.8-rc7 crash: WARNING: suspicious RCU usage in ctrl_cmd_new_lookup WARNING: suspicious RCU usage 5.8.0-rc7-syzkaller #0 Not tainted ----------------------------- include/linux/radix-tree.h:176 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by kworker/u4:5/4394: #0: ffff88812b139138 ((wq_completion)qrtr_ns_handler){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff88812b139138 ((wq_completion)qrtr_ns_handler){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff88812b139138 ((wq_completion)qrtr_ns_handler){+.+.}-{0:0}, at: process_one_work+0x1de/0x5f0 kernel/workqueue.c:2240 #1: ffffc9000173fe70 ((work_completion)(&qrtr_ns.work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc9000173fe70 ((work_completion)(&qrtr_ns.work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc9000173fe70 ((work_completion)(&qrtr_ns.work)){+.+.}-{0:0}, at: process_one_work+0x1de/0x5f0 kernel/workqueue.c:2240 stack backtrace: CPU: 0 PID: 4394 Comm: kworker/u4:5 Not tainted 5.8.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: qrtr_ns_handler qrtr_ns_worker Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xb3/0xec lib/dump_stack.c:118 radix_tree_deref_slot include/linux/radix-tree.h:176 [inline] ctrl_cmd_new_lookup+0x284/0x2b0 net/qrtr/ns.c:558 qrtr_ns_worker+0x11a/0x717 net/qrtr/ns.c:674 process_one_work+0x26a/0x5f0 kernel/workqueue.c:2269 worker_thread+0x38/0x380 kernel/workqueue.c:2415 kthread+0x148/0x170 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification failed to send lookup notification