bisecting fixing commit since 31acccdc877486a649a86d37725a15175fcd5ed6 building syzkaller on 1bf9a662c66aa432ff2fe3bf2562578cef626c09 testing commit 31acccdc877486a649a86d37725a15175fcd5ed6 with gcc (GCC) 8.1.0 kernel signature: 41b2609fb6a86aefe1c52c43dee63dd354273664461a90299aa87460bca59b0a all runs: crashed: INFO: task hung in rdma_destroy_id testing current HEAD 13d2ce42de8cb98ff952f8de6307f896203854c2 testing commit 13d2ce42de8cb98ff952f8de6307f896203854c2 with gcc (GCC) 8.1.0 kernel signature: d7c345a6e9a2056b66ca22073feb458a77fe853da54c3734ab49a6c19370489b all runs: crashed: INFO: task hung in rdma_destroy_id revisions tested: 2, total time: 33m34.04136033s (build: 17m57.250169999s, test: 14m41.283073629s) the crash still happens on HEAD commit msg: Linux 4.19.163 crash: INFO: task hung in rdma_destroy_id Bluetooth: hci2: command 0x0406 tx timeout Bluetooth: hci4: command 0x0406 tx timeout Bluetooth: hci5: command 0x0406 tx timeout INFO: task syz-executor.2:3483 blocked for more than 140 seconds. Not tainted 4.19.163-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28232 3483 7815 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:1794 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+0x18/0x20 kernel/sched/completion.c:136 rdma_destroy_id+0x431/0x7e0 drivers/infiniband/core/cma.c:1750 ucma_close+0x107/0x2f0 drivers/infiniband/core/ucma.c:1819 __fput+0x249/0x7f0 fs/file_table.c:278 ____fput+0x9/0x10 fs/file_table.c:309 task_work_run+0x108/0x180 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x185/0x1e0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x413/0x4e0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x417811 Code: Bad RIP value. RSP: 002b:00007ffdf13b2570 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417811 RDX: 0000001b2bf20000 RSI: 0000000000000001 RDI: 0000000000000003 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 00007ffdf13b2650 R11: 0000000000000293 R12: ffffffffffffffff R13: 000000000002c60b R14: 00000000000003e8 R15: 000000000118bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1566: #0: 00000000b8b8b23b (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 1 lock held by in:imklog/7190: #0: 00000000b10bbff6 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1566 Comm: khungtaskd Not tainted 4.19.163-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+0xf6/0x11a 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