bisecting fixing commit since 4ba8e26127c393c32776dff6d79c5b82de6dc542 building syzkaller on 5da9499f431225d763a8dbb3410ca4856cb865b9 testing commit 4ba8e26127c393c32776dff6d79c5b82de6dc542 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 757fb0ffaab0567645d21b64b93dcda81bc9279282e66d1bdea7b779cee5d7b7 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: unregister_netdevice: waiting for DEV to become free run #3: crashed: unregister_netdevice: waiting for DEV to become free 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: unregister_netdevice: waiting for DEV to become free 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: INFO: rcu detected stall in chrdev_open run #16: crashed: INFO: rcu detected stall in corrupted run #17: crashed: INFO: rcu detected stall in corrupted run #18: crashed: INFO: rcu detected stall in corrupted run #19: crashed: INFO: rcu detected stall in corrupted testing current HEAD a35d65bedfbc38cffe2701798cd6810bbdf07892 testing commit a35d65bedfbc38cffe2701798cd6810bbdf07892 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: e2e32d3f60bc779b9ab2ff13708baa3b662c44359101f6303ccfc8f8ed8b5997 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: unregister_netdevice: waiting for DEV to become free run #3: crashed: unregister_netdevice: waiting for DEV to become free 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: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in chrdev_open run #9: crashed: INFO: rcu detected stall in corrupted revisions tested: 2, total time: 28m19.298177662s (build: 17m38.416694967s, test: 9m53.447428379s) the crash still happens on HEAD commit msg: Linux 4.14.267 crash: INFO: rcu detected stall in corrupted hrtimer: interrupt took 33476 ns INFO: rcu_preempt detected stalls on CPUs/tasks: INFO: rcu_sched detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=335, c=334, q=8) (detected by 1, t=10502 jiffies, g=1162, c=1161, q=138) All QSes seen, last rcu_sched kthread activity 10502 (4294952565-4294942063), jiffies_till_next_fqs=1, root ->qsmask 0x0 All QSes seen, last rcu_preempt kthread activity 10502 (4294952565-4294942063), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor753 R syz-executor753 R running task 26832 8582 8335 0x00000000 running task Call Trace: 27192 8581 8332 0x00000000 Call Trace: sched_show_task kernel/sched/core.c:5168 [inline] sched_show_task.cold.22+0x343/0x3a7 kernel/sched/core.c:5143 sched_show_task kernel/sched/core.c:5168 [inline] sched_show_task.cold.22+0x343/0x3a7 kernel/sched/core.c:5143 print_other_cpu_stall kernel/rcu/tree.c:1501 [inline] check_cpu_stall kernel/rcu/tree.c:1616 [inline] __rcu_pending kernel/rcu/tree.c:3390 [inline] rcu_pending kernel/rcu/tree.c:3452 [inline] rcu_check_callbacks.cold.59+0xcbc/0xd13 kernel/rcu/tree.c:2792 print_other_cpu_stall kernel/rcu/tree.c:1501 [inline] check_cpu_stall kernel/rcu/tree.c:1616 [inline] __rcu_pending kernel/rcu/tree.c:3390 [inline] rcu_pending kernel/rcu/tree.c:3452 [inline] rcu_check_callbacks.cold.59+0xcbc/0xd13 kernel/rcu/tree.c:2792 update_process_times+0x2a/0x60 kernel/time/timer.c:1591 update_process_times+0x2a/0x60 kernel/time/timer.c:1591 tick_sched_handle.isra.5+0x6f/0x140 kernel/time/tick-sched.c:165 tick_sched_handle.isra.5+0x6f/0x140 kernel/time/tick-sched.c:165 tick_sched_timer+0x39/0xf0 kernel/time/tick-sched.c:1223 tick_sched_timer+0x39/0xf0 kernel/time/tick-sched.c:1223 __run_hrtimer kernel/time/hrtimer.c:1223 [inline] __hrtimer_run_queues+0x279/0xad0 kernel/time/hrtimer.c:1287 __run_hrtimer kernel/time/hrtimer.c:1223 [inline] __hrtimer_run_queues+0x279/0xad0 kernel/time/hrtimer.c:1287 hrtimer_interrupt+0x1ae/0x600 kernel/time/hrtimer.c:1321 hrtimer_interrupt+0x1ae/0x600 kernel/time/hrtimer.c:1321 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline] smp_apic_timer_interrupt+0x11f/0x5d0 arch/x86/kernel/apic/apic.c:1104 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline] smp_apic_timer_interrupt+0x11f/0x5d0 arch/x86/kernel/apic/apic.c:1104 apic_timer_interrupt+0x9a/0xa0 arch/x86/entry/entry_64.S:793 apic_timer_interrupt+0x9a/0xa0 arch/x86/entry/entry_64.S:793 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline] RIP: 0010:kfree+0x1f1/0x270 mm/slab.c:3816 RIP: 0010:update_stack_state+0x3a0/0x650 arch/x86/kernel/unwind_frame.c:208 RSP: 0018:ffff8880aad8f390 EFLAGS: 00000282 RSP: 0018:ffff888091d47888 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10 RAX: ffff8880aad88001 RBX: ffff8880aad8fcc0 RCX: 1ffff110155b1eb0 ORIG_RAX: ffffffffffffff10 RDX: dffffc0000000000 RSI: ffff8880aad8fcc0 RDI: ffff8880aad8f588 RBP: ffff8880aad8f458 R08: 1ffff110155b1eb2 R09: ffff8880aad8f578 RAX: 0000000000000007 RBX: ffff88809aca70c0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000282 R10: ffff8880aad8f4f0 R11: ffff8880aad8f59f R12: ffffed10155b1e7a R13: ffff8880aad8f530 R14: ffff8880aad8f540 R15: ffff8880aad8f580 RBP: ffff888091d478a8 R08: 000000000000000d R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000282 R13: ffff88813fe501c0 R14: ffffffff8359ab4e R15: fffffbfff15f8a11 unwind_next_frame.part.6+0x1a3/0xa40 arch/x86/kernel/unwind_frame.c:333 tty_free_file drivers/tty/tty_io.c:219 [inline] tty_open+0x31e/0x8e0 drivers/tty/tty_io.c:2024 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 unwind_next_frame+0x35/0x40 arch/x86/kernel/unwind_frame.c:287 __save_stack_trace+0x6e/0xd0 arch/x86/kernel/stacktrace.c:44 do_dentry_open+0x3e4/0xde0 fs/open.c:777 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 vfs_open+0xfc/0x240 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0xb6f/0x2760 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1d0/0x350 fs/open.c:1081 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 SYSC_openat fs/open.c:1108 [inline] SyS_openat+0xf/0x20 fs/open.c:1102 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 slab_post_alloc_hook mm/slab.h:442 [inline] slab_alloc mm/slab.c:3390 [inline] kmem_cache_alloc_trace+0x13b/0x3f0 mm/slab.c:3616 kmalloc include/linux/slab.h:488 [inline] tty_alloc_file drivers/tty/tty_io.c:186 [inline] tty_open+0x135/0x8e0 drivers/tty/tty_io.c:2015 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fb02c6d8ae9 RSP: 002b:00007fb02c68a318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423 RAX: ffffffffffffffda RBX: 00007fb02c7603e8 RCX: 00007fb02c6d8ae9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007fb02c7603e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007ffd6fdc3a1f R14: 00007fb02c68a400 R15: 0000000000022000 rcu_sched kthread starved for 10502 jiffies! g335 c334 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1 do_dentry_open+0x3e4/0xde0 fs/open.c:777 rcu_sched R running task 29752 9 2 0x80000000 vfs_open+0xfc/0x240 fs/open.c:888 Call Trace: context_switch kernel/sched/core.c:2811 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3387 do_last fs/namei.c:3428 [inline] path_openat+0xb6f/0x2760 fs/namei.c:3569 schedule+0x7f/0x1b0 kernel/sched/core.c:3431 schedule_timeout+0x41f/0xcc0 kernel/time/timer.c:1747 do_filp_open+0x16b/0x220 fs/namei.c:3603 rcu_gp_kthread+0xb69/0x1df0 kernel/rcu/tree.c:2255 kthread+0x338/0x400 kernel/kthread.c:232 do_sys_open+0x1d0/0x350 fs/open.c:1081 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 SYSC_openat fs/open.c:1108 [inline] SyS_openat+0xf/0x20 fs/open.c:1102 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fb02c6d8ae9 RSP: 002b:00007fb02c68a318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fb02c7603e8 RCX: 00007fb02c6d8ae9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007fb02c7603e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007ffd6fdc3a1f R14: 00007fb02c68a400 R15: 0000000000022000 rcu_preempt kthread starved for 10502 jiffies! g1162 c1161 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 rcu_preempt R running task 29720 8 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2811 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3387 preempt_schedule_common+0x1f/0xe0 kernel/sched/core.c:3511 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3537 ___preempt_schedule+0x16/0x18 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0xbb/0xd0 kernel/locking/spinlock.c:192 debug_object_free lib/debugobjects.c:613 [inline] debug_object_free+0x22d/0x390 lib/debugobjects.c:586 destroy_timer_on_stack kernel/time/timer.c:724 [inline] schedule_timeout+0x441/0xcc0 kernel/time/timer.c:1751 rcu_gp_kthread+0xb69/0x1df0 kernel/rcu/tree.c:2255 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404