bisecting fixing commit since 96d454cd2c1668010406ea4c28ab915bcbb747f4 building syzkaller on d5a3ae1f760e7cb2cd5a721d9645ae22eae114fe testing commit 96d454cd2c1668010406ea4c28ab915bcbb747f4 with gcc (GCC) 8.1.0 kernel signature: bf115351b70b00066b9d48f31ea766ac746ffc7314ed74c69b0afe36a2f13f13 run #0: crashed: INFO: task hung in do_proc_bulk run #1: crashed: INFO: task hung in do_proc_bulk run #2: crashed: INFO: task hung in do_proc_bulk run #3: crashed: INFO: task hung in do_proc_bulk run #4: crashed: INFO: task hung in do_proc_bulk run #5: crashed: INFO: task hung in do_proc_bulk run #6: crashed: INFO: task hung in do_proc_bulk run #7: OK run #8: OK run #9: OK testing current HEAD 85a2c56cb4454c73f56d3099d96942e7919b292f testing commit 85a2c56cb4454c73f56d3099d96942e7919b292f with gcc (GCC) 8.1.0 kernel signature: c875cae7a585bdff271cae697cec1019d7bc25eb9b3fd6552c2336a023936f7f run #0: crashed: INFO: task hung in do_proc_bulk run #1: crashed: INFO: task hung in do_proc_bulk run #2: crashed: INFO: task hung in do_proc_bulk run #3: crashed: INFO: task hung in do_proc_bulk run #4: crashed: INFO: task hung in do_proc_bulk run #5: crashed: INFO: task hung in do_proc_bulk run #6: OK run #7: OK run #8: OK run #9: OK revisions tested: 2, total time: 30m39.362858026s (build: 9m14.611368351s, test: 20m54.520255802s) the crash still happens on HEAD commit msg: Merge tag 'pm-5.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm crash: INFO: task hung in do_proc_bulk INFO: task syz-executor.5:7576 blocked for more than 143 seconds. Not tainted 5.10.0-rc5-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.5 state:D stack:14088 pid: 7576 ppid: 6156 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:3779 [inline] __schedule+0x404/0x890 kernel/sched/core.c:4528 schedule+0x38/0xe0 kernel/sched/core.c:4606 schedule_timeout+0x233/0x2e0 kernel/time/timer.c:1847 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion_timeout+0xa2/0x110 kernel/sched/completion.c:157 usb_start_wait_urb+0x7d/0xf0 drivers/usb/core/message.c:63 do_proc_bulk+0x13f/0x2f0 drivers/usb/core/devio.c:1231 proc_bulk_compat drivers/usb/core/devio.c:2052 [inline] usbdev_do_ioctl drivers/usb/core/devio.c:2603 [inline] usbdev_ioctl+0x6e6/0x10e0 drivers/usb/core/devio.c:2708 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x7c/0xb0 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 RSP: 002b:00007f08d51c2c78 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: 00007fff460055ff R14: 00007f08d51c39c0 R15: 000000000118cf4c Showing all locks held in the system: 2 locks held by kworker/u4:0/7: #0: ffff888237d2db98 (&rq->lock){-.-.}-{2:2}, at: newidle_balance+0x430/0x630 kernel/sched/fair.c:10597 #1: ffffffff843d8940 (rcu_read_lock){....}-{1:2}, at: __update_idle_core+0x0/0x200 kernel/sched/fair.c:5215 1 lock held by khungtaskd/1174: #0: ffffffff843d8940 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x15/0x17a kernel/locking/lockdep.c:6255 1 lock held by in:imklog/5770: #0: ffff88810149b2f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x45/0x50 fs/file.c:932 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1174 Comm: khungtaskd Not tainted 5.10.0-rc5-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+0xa3/0xc8 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.8+0x53/0x6d lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0xd5/0xf0 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+0x57f/0x670 kernel/hung_task.c:294 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60