bisecting fixing commit since 9dfbac0e6b8600043de8dc85ed072f5f1342dc15 building syzkaller on d018dd31bfa66650daec4d49dc7b264a827e7834 testing commit 9dfbac0e6b8600043de8dc85ed072f5f1342dc15 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: e816c2ba596af62d7d42c7cca12b3eee1ac249a542ebb41b2d51e54ebaf960fc run #0: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #1: crashed: unregister_netdevice: waiting for DEV to become free run #2: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #3: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #4: crashed: unregister_netdevice: waiting for DEV to become free run #5: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #6: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #7: crashed: unregister_netdevice: waiting for DEV to become free run #8: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #9: crashed: unregister_netdevice: waiting for DEV to become free run #10: crashed: unregister_netdevice: waiting for DEV to become free run #11: crashed: unregister_netdevice: waiting for DEV to become free run #12: crashed: unregister_netdevice: waiting for DEV to become free run #13: crashed: unregister_netdevice: waiting for DEV to become free run #14: crashed: unregister_netdevice: waiting for DEV to become free run #15: crashed: unregister_netdevice: waiting for DEV to become free run #16: crashed: unregister_netdevice: waiting for DEV to become free run #17: crashed: unregister_netdevice: waiting for DEV to become free run #18: crashed: unregister_netdevice: waiting for DEV to become free run #19: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc testing current HEAD af48f51cb5934738a3ee97e951d7dededf029488 testing commit af48f51cb5934738a3ee97e951d7dededf029488 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 98a35af998dab04450c262e9d59ac6e63975713010c27ab45dec76b1c6341888 run #0: crashed: unregister_netdevice: waiting for DEV to become free run #1: crashed: unregister_netdevice: waiting for DEV to become free run #2: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #3: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #4: crashed: unregister_netdevice: waiting for DEV to become free run #5: crashed: unregister_netdevice: waiting for DEV to become free run #6: crashed: unregister_netdevice: waiting for DEV to become free run #7: crashed: unregister_netdevice: waiting for DEV to become free run #8: crashed: BUG: sleeping function called from invalid context in ep_ptable_queue_proc run #9: crashed: unregister_netdevice: waiting for DEV to become free revisions tested: 2, total time: 24m54.216194413s (build: 17m48.964011658s, test: 6m27.974339247s) the crash still happens on HEAD commit msg: Linux 4.14.271 crash: unregister_netdevice: waiting for DEV to become free IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready syz-executor.0 (7947) used greatest stack depth: 23784 bytes left can: request_module (can-proto-0) failed. can: request_module (can-proto-0) failed. can: request_module (can-proto-0) failed. unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1 BUG: sleeping function called from invalid context at mm/slab.h:419 in_atomic(): 1, irqs_disabled(): 1, pid: 8279, name: syz-executor388 3 locks held by syz-executor388/8279: #0: (&ep->mtx){+.+.}, at: [] SYSC_epoll_ctl fs/eventpoll.c:2080 [inline] #0: (&ep->mtx){+.+.}, at: [] SyS_epoll_ctl+0x4bc/0x27e0 fs/eventpoll.c:2002 #1: (&dev->dev_mutex){+.+.}, at: [] v4l2_m2m_fop_poll+0x8c/0x100 drivers/media/v4l2-core/v4l2-mem2mem.c:802 #2: (&(&q->done_lock)->rlock){....}, at: [] v4l2_m2m_poll+0x103/0x650 drivers/media/v4l2-core/v4l2-mem2mem.c:536 unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1 irq event stamp: 6650 hardirqs last enabled at (6649): [] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] hardirqs last enabled at (6649): [] _raw_spin_unlock_irqrestore+0x82/0xd0 kernel/locking/spinlock.c:192 hardirqs last disabled at (6650): [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] hardirqs last disabled at (6650): [] _raw_spin_lock_irqsave+0x74/0xd0 kernel/locking/spinlock.c:160 softirqs last enabled at (5268): [] __do_softirq+0x644/0x9a2 kernel/softirq.c:314 softirqs last disabled at (5251): [] invoke_softirq kernel/softirq.c:368 [inline] softirqs last disabled at (5251): [] irq_exit+0x15f/0x1a0 kernel/softirq.c:409 Preemption disabled at: [] v4l2_m2m_poll+0x103/0x650 drivers/media/v4l2-core/v4l2-mem2mem.c:536 CPU: 0 PID: 8279 Comm: syz-executor388 Not tainted 4.14.271-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+0x14b/0x1e7 lib/dump_stack.c:58 ___might_sleep.cold.19+0x1f1/0x265 kernel/sched/core.c:6041 __might_sleep+0x93/0xb0 kernel/sched/core.c:5994 slab_pre_alloc_hook mm/slab.h:419 [inline] slab_alloc mm/slab.c:3376 [inline] kmem_cache_alloc+0x2a1/0x3e0 mm/slab.c:3550 ep_ptable_queue_proc+0xbd/0x3d0 fs/eventpoll.c:1255 poll_wait include/linux/poll.h:50 [inline] v4l2_m2m_poll+0x4c5/0x650 drivers/media/v4l2-core/v4l2-mem2mem.c:538 v4l2_m2m_fop_poll+0x9a/0x100 drivers/media/v4l2-core/v4l2-mem2mem.c:804 v4l2_poll+0x122/0x1f0 drivers/media/v4l2-core/v4l2-dev.c:342 ep_item_poll fs/eventpoll.c:885 [inline] ep_insert fs/eventpoll.c:1490 [inline] SYSC_epoll_ctl fs/eventpoll.c:2117 [inline] SyS_epoll_ctl+0x13c6/0x27e0 fs/eventpoll.c:2002 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f2a339ecd09 RSP: 002b:00007ffe455f0718 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2a339ecd09 RDX: 0000000000000003 RSI: 0000000000000001 RDI: 0000000000000004 RBP: 00007f2a339b0eb0 R08: 0000000000000000 R09: 0000000000000000