bisecting fixing commit since 7cc2a8ea104820dd9e702202621e8fd4d9f6c8cf building syzkaller on 510951950dc0ee69cfdaf746061d3dbe31b49fd8 testing commit 7cc2a8ea104820dd9e702202621e8fd4d9f6c8cf with gcc (GCC) 8.1.0 kernel signature: dd5bcac7cc69ce310218a7047caa021b7c1d910e1bc1c63dcba8123abee9efe9 run #0: crashed: INFO: rcu detected stall in tipc_release run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in tipc_release run #3: crashed: INFO: rcu detected stall in tipc_release run #4: crashed: INFO: rcu detected stall in tipc_release run #5: crashed: INFO: rcu detected stall in tipc_release run #6: crashed: INFO: rcu detected stall in tipc_release run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in tipc_release run #9: boot failed: can't ssh into the instance testing current HEAD d01e7f10dae29eba0f9ada82b65d24e035d5b2f9 testing commit d01e7f10dae29eba0f9ada82b65d24e035d5b2f9 with gcc (GCC) 8.1.0 kernel signature: 23b23f0d9cf8779aecf44f2e35e1cdb69848423f8704180af8818507a9473e5f run #0: crashed: INFO: rcu detected stall in tipc_release run #1: OK run #2: OK run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK reproducer seems to be flaky Reproducer flagged being flaky revisions tested: 2, total time: 31m13.206310743s (build: 10m3.486157613s, test: 20m35.178868237s) the crash still happens on HEAD commit msg: Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace crash: INFO: rcu detected stall in tipc_release rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=5fa/1/0x4000000000000000 softirq=13118/13121 fqs=11 (t=10502 jiffies g=11981 q=442) rcu: rcu_preempt kthread starved for 10481 jiffies! g11981 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:14648 pid: 10 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4327 [inline] __schedule+0x420/0x8c0 kernel/sched/core.c:5078 schedule+0x38/0xe0 kernel/sched/core.c:5157 schedule_timeout+0x1be/0x2e0 kernel/time/timer.c:1878 rcu_gp_fqs_loop kernel/rcu/tree.c:1940 [inline] rcu_gp_kthread+0x758/0xcc0 kernel/rcu/tree.c:2113 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 NMI backtrace for cpu 1 CPU: 1 PID: 8596 Comm: syz-executor.3 Not tainted 5.10.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0xa3/0xc8 lib/dump_stack.c:120 nmi_cpu_backtrace.cold.8+0x53/0x6d lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0xd5/0xf0 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0xa2/0xce kernel/rcu/tree_stall.h:337 print_cpu_stall kernel/rcu/tree_stall.h:569 [inline] check_cpu_stall kernel/rcu/tree_stall.h:643 [inline] rcu_pending kernel/rcu/tree.c:3751 [inline] rcu_sched_clock_irq.cold.97+0x61/0x5eb kernel/rcu/tree.c:2580 update_process_times+0x8e/0xc0 kernel/time/timer.c:1782 tick_sched_handle.isra.21+0x1a/0x50 kernel/time/tick-sched.c:226 tick_sched_timer+0x6a/0x80 kernel/time/tick-sched.c:1376 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1e3/0x4f0 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0xf9/0x210 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x8e/0x290 arch/x86/kernel/apic/apic.c:1102 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xcc/0xf0 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:should_resched arch/x86/include/asm/preempt.h:102 [inline] RIP: 0010:__local_bh_enable_ip+0xb2/0x130 kernel/softirq.c:203 Code: 7a e4 7e a9 00 ff ff 00 74 71 bf 01 00 00 00 e8 14 f4 02 00 e8 9f 96 10 00 48 83 3d 5f c2 0f 03 00 74 7f fb 66 0f 1f 44 00 00 <65> 8b 05 77 7a e4 7e 85 c0 75 05 e8 55 41 e3 ff 5b 5d c3 65 8b 05 RSP: 0018:ffffc90005f1f720 EFLAGS: 00000282 RAX: 00000000146e6fa0 RBX: 0000000000000201 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff83f318c3 RDI: ffffffff83f6ed2e RBP: ffffffff82ec7d2e R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000001 R12: 000000003bce0f78 R13: ffffc90005f1f8c8 R14: ffff888100b44188 R15: ffff88810e3d8800 spin_unlock_bh include/linux/spinlock.h:399 [inline] tipc_skb_peek_port net/tipc/msg.h:1257 [inline] tipc_sk_rcv+0xbe/0x820 net/tipc/socket.c:2484 tipc_node_xmit+0x11d/0x470 net/tipc/node.c:1689 tipc_node_xmit_skb+0x34/0x50 net/tipc/node.c:1749 tipc_sk_rcv+0x6ad/0x820 net/tipc/socket.c:2515 tipc_node_xmit+0x11d/0x470 net/tipc/node.c:1689 tipc_sk_push_backlog+0xa0/0x150 net/tipc/socket.c:1322 tipc_sk_filter_connect net/tipc/socket.c:2248 [inline] tipc_sk_filter_rcv+0x3b3/0x10e0 net/tipc/socket.c:2357 tipc_sk_enqueue net/tipc/socket.c:2438 [inline] tipc_sk_rcv+0x46c/0x820 net/tipc/socket.c:2490 tipc_node_xmit+0x11d/0x470 net/tipc/node.c:1689 tipc_node_xmit_skb net/tipc/node.c:1749 [inline] tipc_node_distr_xmit+0x5a/0xe0 net/tipc/node.c:1764 tipc_sk_backlog_rcv+0x53/0x80 net/tipc/socket.c:2405 sk_backlog_rcv include/net/sock.h:1016 [inline] __release_sock+0x68/0x100 net/core/sock.c:2542 release_sock+0x26/0xa0 net/core/sock.c:3066 tipc_release+0x3d5/0x870 net/tipc/socket.c:654 __sock_release+0x32/0xa0 net/socket.c:597 sock_close+0xf/0x20 net/socket.c:1256 __fput+0xa1/0x250 fs/file_table.c:280 task_work_run+0x68/0xb0 kernel/task_work.c:168 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45cba9 Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f4c7bda6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000021 RAX: 0000000000000004 RBX: 00000000004dc020 RCX: 000000000045cba9 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007 R13: 00000000000000a4 R14: 00000000004c3748 R15: 00007f4c7bda76d4