Hello, syzbot found the following issue on: HEAD commit: 5c8fe583 Linux 5.11-rc1 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13ecd077500000 kernel config: https://syzkaller.appspot.com/x/.config?x=a6998cf893b79850 dashboard link: https://syzkaller.appspot.com/bug?extid=b73659f5bb96fac34820 compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b73659f5bb96fac34820@xxxxxxxxxxxxxxxxxxxxxxxxx INFO: task syz-executor.1:24596 blocked for more than 143 seconds. Not tainted 5.11.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.1 state:D stack:28136 pid:24596 ppid: 8491 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x90c/0x21a0 kernel/sched/core.c:5064 schedule+0xcf/0x270 kernel/sched/core.c:5143 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:5202 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x81a/0x1110 kernel/locking/mutex.c:1103 device_lock include/linux/device.h:725 [inline] usbdev_open+0x19d/0x930 drivers/usb/core/devio.c:1029 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4b9/0x11b0 fs/open.c:817 do_open fs/namei.c:3254 [inline] path_openat+0x1b9a/0x2730 fs/namei.c:3371 do_filp_open+0x17e/0x3c0 fs/namei.c:3398 do_sys_openat2+0x16d/0x420 fs/open.c:1172 do_sys_open fs/open.c:1188 [inline] __do_sys_open fs/open.c:1196 [inline] __se_sys_open fs/open.c:1192 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1192 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x417d91 RSP: 002b:00007f6b4f064810 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000417d91 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00007f6b4f064840 RBP: 000000000119bfc0 R08: 000000000000000f R09: 2330302f6273752f R10: 00007f6b4f0659d0 R11: 0000000000000293 R12: 000000000119bf8c R13: 00007ffcee50333f R14: 00007f6b4f0659c0 R15: 000000000119bf8c Showing all locks held in the system: 2 locks held by kworker/u4:4/164: #0: ffff8880b9f34c58 (&rq->lock){-.-.}-{2:2}, at: newidle_balance+0x789/0xe50 kernel/sched/fair.c:10642 #1: ffffc900015afda8 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x15f0 kernel/workqueue.c:2250 1 lock held by khungtaskd/1660: #0: ffffffff8b363860 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6254 1 lock held by in:imklog/8320: #0: ffff8880153ced70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:949 2 locks held by rs:main Q:Reg/8325: 5 locks held by kworker/0:16/16221: #0: ffff888014df2538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888014df2538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888014df2538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888014df2538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888014df2538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888014df2538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x871/0x15f0 kernel/workqueue.c:2246 #1: ffffc900166bfda8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x15f0 kernel/workqueue.c:2250 #2: ffff888144c5e218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:725 [inline] #2: ffff888144c5e218 (&dev->mutex){....}-{3:3}, at: hub_event+0x1c5/0x42d0 drivers/usb/core/hub.c:5537 #3: ffff8880640a6578 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3030 [inline] #3: ffff8880640a6578 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5154 [inline] #3: ffff8880640a6578 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5363 [inline] #3: ffff8880640a6578 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5509 [inline] #3: ffff8880640a6578 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x216c/0x42d0 drivers/usb/core/hub.c:5591 #4: ffff888144b57768 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_init+0x1b2/0x2dd0 drivers/usb/core/hub.c:4582 1 lock held by syz-executor.1/24596: #0: ffff888144c5e218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:725 [inline] #0: ffff888144c5e218 (&dev->mutex){....}-{3:3}, at: usbdev_open+0x19d/0x930 drivers/usb/core/devio.c:1029 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1660 Comm: khungtaskd Not tainted 5.11.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd43/0xfa0 kernel/hung_task.c:294 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 164 Comm: kworker/u4:4 Not tainted 5.11.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:84 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:101 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:127 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:158 [inline] RIP: 0010:check_memory_region_inline mm/kasan/generic.c:176 [inline] RIP: 0010:check_memory_region+0xde/0x180 mm/kasan/generic.c:185 Code: 74 f2 48 89 c2 b8 01 00 00 00 48 85 d2 75 56 5b 5d 41 5c c3 48 85 d2 74 5e 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 50 80 38 00 <74> f2 eb d4 41 bc 08 00 00 00 48 89 ea 45 29 dc 4d 8d 1c 2c eb 0c RSP: 0018:ffffc900015afa38 EFLAGS: 00000046 RAX: fffffbfff1d7ab0d RBX: fffffbfff1d7ab0e RCX: ffffffff81582ac7 RDX: fffffbfff1d7ab0e RSI: 0000000000000008 RDI: ffffffff8ebd5868 RBP: fffffbfff1d7ab0d R08: 0000000000000000 R09: ffffffff8ebd586f R10: fffffbfff1d7ab0d R11: 0000000000000000 R12: 000000000000067c R13: 0000000000000004 R14: dffffc0000000000 R15: ffff888011704108 FS: 0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f934008f010 CR3: 0000000010ed3000 CR4: 0000000000350ef0 Call Trace: instrument_atomic_read include/linux/instrumented.h:71 [inline] test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline] hlock_class kernel/locking/lockdep.c:198 [inline] check_wait_context kernel/locking/lockdep.c:4531 [inline] __lock_acquire+0x707/0x5500 kernel/locking/lockdep.c:4782 lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402 rcu_lock_acquire include/linux/rcupdate.h:253 [inline] rcu_read_lock include/linux/rcupdate.h:642 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:404 [inline] batadv_nc_worker+0x12d/0xe50 net/batman-adv/network-coding.c:715 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 --- This report is generated by a bot. 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