bisecting cause commit starting from 2187f215ebaac73ddbd814696d7c7fa34f0c3de0 building syzkaller on 79b211f74b08737aeb4934c6ff69a263b3c38013 testing commit 2187f215ebaac73ddbd814696d7c7fa34f0c3de0 with gcc (GCC) 8.1.0 kernel signature: 22c913d242a37dbda3069c268952b8435d049830 run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in do_signal testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: 90e3325bf598bc693fd8d8d17e8e8891fcdce170 run #0: crashed: INFO: rcu detected stall in bad_area run #1: crashed: INFO: rcu detected stall in bad_area run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in do_signal run #9: crashed: INFO: rcu detected stall in corrupted testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: b93996cc9b3afcd88cd2e5eeb647963fd14e7483 run #0: crashed: INFO: rcu detected stall in __do_page_fault run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in bad_area run #3: crashed: INFO: rcu detected stall in bad_area run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in do_signal run #9: crashed: INFO: rcu detected stall in do_signal testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: 98c4e347bc8f40f1f1c9bb2a25baf4221bdf56d4 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in bad_area testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: 4ef96eda12cd82027e0307159c2069982b028240 run #0: crashed: INFO: rcu detected stall in bad_area run #1: crashed: INFO: rcu detected stall in __do_page_fault run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in lock_is_held_type run #5: crashed: INFO: rcu detected stall in __do_page_fault run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: INFO: rcu detected stall in bad_area run #8: crashed: INFO: rcu detected stall in do_signal run #9: crashed: INFO: rcu detected stall in do_signal testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: 3b2e04e13d0b6eec162b995642d254fbbd0a9fdf run #0: crashed: INFO: rcu detected stall in bad_area run #1: crashed: INFO: rcu detected stall in bad_area run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in exit_to_usermode_loop run #4: crashed: INFO: rcu detected stall in bad_area run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in do_signal run #9: crashed: INFO: rcu detected stall in do_signal testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 kernel signature: eacfcb21647aee3de7f306ada7f11a6a29116d4c run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in lock_is_held_type run #2: crashed: INFO: rcu detected stall in bad_area run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in bad_area run #8: crashed: INFO: rcu detected stall in do_signal run #9: crashed: INFO: rcu detected stall in do_signal testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 kernel signature: 09203024af7f6d5901095465abff18a2b7d58da4 run #0: crashed: INFO: rcu detected stall in find_vma run #1: crashed: INFO: rcu detected stall in __do_page_fault run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in bad_area run #4: crashed: INFO: rcu detected stall in bad_area run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in bad_area run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in bad_area testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 kernel signature: 81496726b6bc6ccd6cc83abd174a0effc353af4b run #0: crashed: INFO: rcu detected stall in bad_area run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in bad_area run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in bad_area testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 kernel signature: 65c6eab84070952b24443162149aeb9ca2e2edc7 run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in bad_area run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in bad_area run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in do_signal testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 kernel signature: 55e24ebd55f36f674378191c9f4a8335e416e88f run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in bad_area run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in do_signal testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 kernel signature: fc3bc616da208a2cb77b08dafdd251b69220aadb run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: no output from test machine run #7: crashed: no output from test machine run #8: crashed: no output from test machine run #9: crashed: no output from test machine testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 kernel signature: 26d4a476806198aa52909fc08605e1ad2bad6ce5 run #0: crashed: INFO: rcu detected stall in bad_area run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in bad_area run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: no output from test machine testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 kernel signature: ec02ddb29483eb830fe52fb43134547c47ac444b run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in bad_area run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in bad_area run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: no output from test machine run #8: crashed: no output from test machine run #9: crashed: no output from test machine testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 kernel signature: bfe414c5ffe2e935dd6d9976c01936db3f2da328 run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in bad_area run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: no output from test machine run #7: crashed: no output from test machine run #8: crashed: no output from test machine run #9: crashed: no output from test machine testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 kernel signature: 6903dbec810ee904088fd4d5a55ed3c5abab7b67 run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: no output from test machine run #7: crashed: no output from test machine run #8: crashed: no output from test machine run #9: crashed: no output from test machine testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 kernel signature: 4eb2837b3bc7cdf02e667b3ebd76e4069a1c0813 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: no output from test machine testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 kernel signature: c5557d7f5f7464b415498626026de9093c5485af run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in bad_area run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: INFO: rcu detected stall in bad_area run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: no output from test machine run #9: crashed: no output from test machine testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 kernel signature: adc74d142cacd2622d6042b471e51a5c897e54b6 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: BUG: workqueue lockup testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 kernel signature: 3c793cc450f4b84dc3a7dd368a9e36bedeebd95f run #0: crashed: INFO: rcu detected stall in bad_area run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in bad_area run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: BUG: workqueue lockup run #8: crashed: BUG: workqueue lockup run #9: crashed: no output from test machine testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 kernel signature: 9c910dbab7e0d3265079375183c78e6f2b8d0162 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in bad_area run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in do_signal revisions tested: 21, total time: 3h55m12.905774526s (build: 1h42m18.908943992s, test: 2h10m48.508053072s) the crash already happened on the oldest tested release commit msg: Linux 4.6 crash: INFO: rcu detected stall in do_signal IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready sched: RT throttling activated hrtimer: interrupt took 44605 ns INFO: rcu_sched detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=-114, c=-115, q=1) All QSes seen, last rcu_sched kthread activity 10500 (4294953928-4294943428), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.0 R running task 28928 7398 7145 0x00000000 0000000000001be9 ffff88012c107ca8 ffffffff813d414c ffffffff81615a00 0000000041b58ab3 ffffffff868f20bf ffffffff813d3ec0 ffff88012c107c68 ffffffff81491fd4 0000000000000000 ffffffff87651000 0000000000000002 Call Trace: [] sched_show_task+0x28c/0x400 kernel/sched/core.c:4976 [] print_other_cpu_stall kernel/rcu/tree.c:1317 [inline] [] check_cpu_stall kernel/rcu/tree.c:1423 [inline] [] __rcu_pending kernel/rcu/tree.c:3883 [inline] [] rcu_pending kernel/rcu/tree.c:3947 [inline] [] rcu_check_callbacks+0x1c5c/0x2010 kernel/rcu/tree.c:2772 [] update_process_times+0x34/0x60 kernel/time/timer.c:1420 [] tick_sched_handle.isra.19+0x44/0xe0 kernel/time/tick-sched.c:151 [] tick_sched_timer+0x64/0xd0 kernel/time/tick-sched.c:1178 [] __run_hrtimer kernel/time/hrtimer.c:1242 [inline] [] __hrtimer_run_queues+0x2d4/0xbf0 kernel/time/hrtimer.c:1306 [] hrtimer_interrupt+0x19d/0x470 kernel/time/hrtimer.c:1340 [] local_apic_timer_interrupt+0x6e/0xf0 arch/x86/kernel/apic/apic.c:907 [] smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:931 [] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:621 [] ? arch_local_irq_enable arch/x86/include/asm/paravirt.h:801 [inline] [] ? __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:170 [inline] [] ? _raw_spin_unlock_irq+0x56/0x80 kernel/locking/spinlock.c:199 [] spin_unlock_irq include/linux/spinlock.h:357 [inline] [] get_signal+0xe61/0x13a0 kernel/signal.c:2310 [] do_signal+0x7f/0x1cd0 arch/x86/kernel/signal.c:784 [] exit_to_usermode_loop+0x16b/0x1c0 arch/x86/entry/common.c:229 [] prepare_exit_to_usermode+0x117/0x140 arch/x86/entry/common.c:264 [] retint_user+0x8/0x20 rcu_sched kthread starved for 10500 jiffies! g18446744073709551502 c18446744073709551501 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 rcu_sched R running task 29392 8 2 0x00000000 ffff88012b0afac8 ffff88012c020400 ffff88012c020d90 ffff88012c020d68 ffff88012c020418 ffff88012b09a1c8 1ffff10000000000 ffff8800bbb56380 ffff88012b09a1c0 ffff88012b0a8000 ffffed0025615001 ffff88012b0a8008 Call Trace: [] schedule+0x9a/0x1c0 kernel/sched/core.c:3250 [] schedule_timeout+0x2e5/0x670 kernel/time/timer.c:1531 [] rcu_gp_kthread+0xee2/0x1f70 kernel/rcu/tree.c:2126 [] kthread+0x209/0x2d0 kernel/kthread.c:209 [] ret_from_fork+0x22/0x50 arch/x86/entry/entry_64.S:392 INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10538 jiffies, g=1847, c=1846, q=24) All QSes seen, last rcu_preempt kthread activity 10538 (4294953966-4294943428), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.0 R running task 28928 7398 7145 0x00000000 0000000000001be9 ffff88012c107ca8 ffffffff813d414c ffffffff81615a00 0000000041b58ab3 ffffffff868f20bf ffffffff813d3ec0 ffff88012c107c68 ffffffff81491fd4 0000000000000000 ffffffff87651000 0000000000000002 Call Trace: [] sched_show_task+0x28c/0x400 kernel/sched/core.c:4976 [] print_other_cpu_stall kernel/rcu/tree.c:1317 [inline] [] check_cpu_stall kernel/rcu/tree.c:1423 [inline] [] __rcu_pending kernel/rcu/tree.c:3883 [inline] [] rcu_pending kernel/rcu/tree.c:3947 [inline] [] rcu_check_callbacks+0x1c5c/0x2010 kernel/rcu/tree.c:2772 [] update_process_times+0x34/0x60 kernel/time/timer.c:1420 [] tick_sched_handle.isra.19+0x44/0xe0 kernel/time/tick-sched.c:151 [] tick_sched_timer+0x64/0xd0 kernel/time/tick-sched.c:1178 [] __run_hrtimer kernel/time/hrtimer.c:1242 [inline] [] __hrtimer_run_queues+0x2d4/0xbf0 kernel/time/hrtimer.c:1306 [] hrtimer_interrupt+0x19d/0x470 kernel/time/hrtimer.c:1340 [] local_apic_timer_interrupt+0x6e/0xf0 arch/x86/kernel/apic/apic.c:907 [] smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:931 [] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:621 [] ? arch_local_irq_enable arch/x86/include/asm/paravirt.h:801 [inline] [] ? __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:170 [inline] [] ? _raw_spin_unlock_irq+0x56/0x80 kernel/locking/spinlock.c:199 [] spin_unlock_irq include/linux/spinlock.h:357 [inline] [] get_signal+0xe61/0x13a0 kernel/signal.c:2310 [] do_signal+0x7f/0x1cd0 arch/x86/kernel/signal.c:784 [] exit_to_usermode_loop+0x16b/0x1c0 arch/x86/entry/common.c:229 [] prepare_exit_to_usermode+0x117/0x140 arch/x86/entry/common.c:264 [] retint_user+0x8/0x20 rcu_preempt kthread starved for 10538 jiffies! g1847 c1846 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 rcu_preempt R running task 29392 7 2 0x00000000 ffff88012b0a7ac8 ffff88012c020400 ffff88012c020d90 ffff88012c020d68 ffff88012c020418 ffff88012b098188 1ffff10000000000 ffff8800afb22280 ffff88012b098180 ffff88012b0a0000 ffffed0025614001 ffff88012b0a0008 Call Trace: [] schedule+0x9a/0x1c0 kernel/sched/core.c:3250 [] schedule_timeout+0x2e5/0x670 kernel/time/timer.c:1531 [] rcu_gp_kthread+0xee2/0x1f70 kernel/rcu/tree.c:2126 [] kthread+0x209/0x2d0 kernel/kthread.c:209 [] ret_from_fork+0x22/0x50 arch/x86/entry/entry_64.S:392