bisecting fixing commit since 4c5bf01e16a7ec59e59a38a61f793c5d1d5560c7 building syzkaller on 25a0186eba20ef6f4f657039ff02eff52a838b1c testing commit 4c5bf01e16a7ec59e59a38a61f793c5d1d5560c7 with gcc (GCC) 8.1.0 kernel signature: 14cf2ee9b5ee42f2ded9f24ad128ee24407dee934cc6fa145f1751cb5838f349 all runs: crashed: WARNING: bad unlock balance in ucma_event_handler testing current HEAD 4f68020fef1c6cf1b680ffb6481ac41379283ea3 testing commit 4f68020fef1c6cf1b680ffb6481ac41379283ea3 with gcc (GCC) 8.1.0 kernel signature: d45330787e133880fcb7642c13618d8892d9cbb88fd2525a8a1fd2e08caa4511 all runs: crashed: WARNING: bad unlock balance in ucma_event_handler revisions tested: 2, total time: 23m46.880633062s (build: 16m38.01458311s, test: 6m18.895598269s) the crash still happens on HEAD commit msg: Linux 4.14.182 crash: WARNING: bad unlock balance in ucma_event_handler IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 ===================================== WARNING: bad unlock balance detected! 4.14.182-syzkaller #0 Not tainted ------------------------------------- kworker/u4:1/22 is trying to release lock (&file->mut) at: [] ucma_event_handler+0x675/0xf80 drivers/infiniband/core/ucma.c:377 but there are no more locks to release! other info that might help us debug this: 4 locks held by kworker/u4:1/22: #0: ("ib_addr"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("ib_addr"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("ib_addr"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("ib_addr"){+.+.}, at: [] process_one_work+0x6cd/0x16c0 kernel/workqueue.c:2087 #1: ((&(&req->work)->work)#2){+.+.}, at: [] process_one_work+0x703/0x16c0 kernel/workqueue.c:2091 #2: (&id_priv->handler_mutex){+.+.}, at: [] addr_handler+0x94/0x260 drivers/infiniband/core/cma.c:2782 #3: (&file->mut){+.+.}, at: [] ucma_event_handler+0xa8/0xf80 drivers/infiniband/core/ucma.c:337 stack backtrace: CPU: 0 PID: 22 Comm: kworker/u4:1 Not tainted 4.14.182-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: ib_addr process_one_req Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 print_unlock_imbalance_bug.cold.62+0x114/0x123 kernel/locking/lockdep.c:3552 __lock_release kernel/locking/lockdep.c:3769 [inline] lock_release+0x623/0x830 kernel/locking/lockdep.c:4017 __mutex_unlock_slowpath+0x7d/0x7e0 kernel/locking/mutex.c:1018 mutex_unlock+0xd/0x10 kernel/locking/mutex.c:614 ucma_event_handler+0x675/0xf80 drivers/infiniband/core/ucma.c:377 addr_handler+0x197/0x260 drivers/infiniband/core/cma.c:2806 process_one_req+0x210/0x4d0 drivers/infiniband/core/addr.c:624 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404