bisecting fixing commit since f6d5cb9e2c06f7d583dd9f4f7cca21d13d78c32a building syzkaller on d5a3ae1f760e7cb2cd5a721d9645ae22eae114fe testing commit f6d5cb9e2c06f7d583dd9f4f7cca21d13d78c32a with gcc (GCC) 8.1.0 kernel signature: f0cd207735aae48102567dc145fa175df87146d3f19503a0a231c4aeee9c1af9 run #0: crashed: INFO: task hung in usb_bulk_msg run #1: crashed: INFO: task hung in usb_bulk_msg run #2: crashed: INFO: task hung in usb_bulk_msg run #3: crashed: INFO: task hung in usb_bulk_msg run #4: crashed: INFO: task hung in usb_bulk_msg run #5: crashed: INFO: task hung in usb_bulk_msg run #6: crashed: INFO: task hung in usb_bulk_msg run #7: OK run #8: OK run #9: OK testing current HEAD ad326970d25cc85128cd22d62398751ad072efff testing commit ad326970d25cc85128cd22d62398751ad072efff with gcc (GCC) 8.1.0 kernel signature: e11dd2cb6b91aa4cd16f192a11fa8d8dca1027279057d3ff97daf80357a383df run #0: crashed: INFO: task hung in usb_bulk_msg run #1: crashed: INFO: task hung in usb_bulk_msg run #2: crashed: INFO: task hung in usb_bulk_msg run #3: crashed: INFO: task hung in usb_bulk_msg run #4: crashed: INFO: task hung in usb_bulk_msg run #5: crashed: INFO: task hung in usb_bulk_msg run #6: OK run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 39m51.15241338s (build: 17m33.310709802s, test: 21m45.621248942s) the crash still happens on HEAD commit msg: Linux 4.19.152 crash: INFO: task hung in usb_bulk_msg Bluetooth: hci3: command 0x0406 tx timeout Bluetooth: hci2: command 0x0406 tx timeout Bluetooth: hci1: command 0x0406 tx timeout Bluetooth: hci5: command 0x0406 tx timeout Bluetooth: hci0: command 0x0406 tx timeout INFO: task syz-executor.4:8094 blocked for more than 140 seconds. Not tainted 4.19.152-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D27752 8094 6617 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x6f6/0xd20 kernel/time/timer.c:1801 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x3fb/0x5d0 kernel/sched/completion.c:115 wait_for_completion_timeout+0xe/0x10 kernel/sched/completion.c:155 usb_start_wait_urb+0x12f/0x280 drivers/usb/core/message.c:62 usb_bulk_msg+0x1d4/0x610 drivers/usb/core/message.c:253 proc_bulk+0x4e5/0x630 drivers/usb/core/devio.c:1206 usbdev_do_ioctl+0x1191/0x28d0 drivers/usb/core/devio.c:2430 usbdev_ioctl+0x9/0x10 drivers/usb/core/devio.c:2580 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45d5b9 Code: 24 48 48 8b 42 08 84 00 48 8b 4a 10 0f b6 5a 18 48 8b 52 20 48 89 54 24 40 83 b8 e4 00 01 00 00 74 3a 48 89 04 24 48 89 4c 24 <08> c6 44 24 10 00 88 5c 24 11 48 8d 05 9e 2b 07 01 48 89 44 24 18 RSP: 002b:00007f38df750c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000001aa80 RCX: 000000000045d5b9 RDX: 0000000020000000 RSI: 00000000c0185502 RDI: 0000000000000003 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe65392ccf R14: 00007f38df7519c0 R15: 000000000118cf4c Showing all locks held in the system: 1 lock held by khungtaskd/1088: #0: 000000000190e20f (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 1 lock held by in:imklog/6030: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1088 Comm: khungtaskd Not tainted 4.19.152-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x17c/0x22a lib/dump_stack.c:118 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x119 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60