bisecting fixing commit since c7ecf3e3a71c216327980f26b1e895ce9b07ad31 building syzkaller on 25a0186eba20ef6f4f657039ff02eff52a838b1c testing commit c7ecf3e3a71c216327980f26b1e895ce9b07ad31 with gcc (GCC) 8.1.0 kernel signature: 4e8ddc97fb80862237116a65f0d3f0f57404f046d2c360fddf4ddcf3ce30972e all runs: crashed: WARNING: bad unlock balance in ucma_event_handler testing current HEAD 765675379b6253b6901563e649a2f87d28ada3ff testing commit 765675379b6253b6901563e649a2f87d28ada3ff with gcc (GCC) 8.1.0 kernel signature: e56b359f02bf90ee242f4c6fc32b88fad5407037b8b1b6509fb5b8407848ae87 all runs: crashed: WARNING: bad unlock balance in ucma_event_handler revisions tested: 2, total time: 25m42.407868643s (build: 18m36.13980664s, test: 6m7.331615411s) the crash still happens on HEAD commit msg: Linux 4.19.119 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! 4.19.119-syzkaller #0 Not tainted ------------------------------------- kworker/u4:2/68 is trying to release lock (&file->mut) at: [] ucma_event_handler+0x681/0xf90 drivers/infiniband/core/ucma.c:396 but there are no more locks to release! other info that might help us debug this: 4 locks held by kworker/u4:2/68: #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline] #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000bb59ba57 ((wq_completion)"ib_addr"){+.+.}, at: process_one_work+0x762/0x1670 kernel/workqueue.c:2126 #1: 000000003544dbbd ((work_completion)(&(&req->work)->work)){+.+.}, at: process_one_work+0x792/0x1670 kernel/workqueue.c:2130 #2: 00000000c1c42a30 (&id_priv->handler_mutex){+.+.}, at: addr_handler+0xac/0x300 drivers/infiniband/core/cma.c:2875 #3: 00000000b76fa90f (&file->mut){+.+.}, at: ucma_event_handler+0xa8/0xf90 drivers/infiniband/core/ucma.c:356 stack backtrace: CPU: 1 PID: 68 Comm: kworker/u4:2 Not tainted 4.19.119-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:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 print_unlock_imbalance_bug.cold.50+0x114/0x123 kernel/locking/lockdep.c:3468 __lock_release kernel/locking/lockdep.c:3678 [inline] lock_release+0x685/0x850 kernel/locking/lockdep.c:3926 __mutex_unlock_slowpath+0x8e/0x6a0 kernel/locking/mutex.c:1197 mutex_unlock+0xd/0x10 kernel/locking/mutex.c:713 ucma_event_handler+0x681/0xf90 drivers/infiniband/core/ucma.c:396 addr_handler+0x23d/0x300 drivers/infiniband/core/cma.c:2908 process_one_req+0xd4/0x5b0 drivers/infiniband/core/addr.c:569 process_one_work+0x830/0x1670 kernel/workqueue.c:2155 worker_thread+0x85/0xb60 kernel/workqueue.c:2298 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415