rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2963/1:b..l (detected by 1, t=10502 jiffies, g=6633, q=115) task:udevd state:R running task stack:26728 pid: 2963 ppid: 1 flags:0x00000000 Call Trace: <TASK> context_switch kernel/sched/core.c:5073 [inline] __schedule+0xa9a/0x4cc0 kernel/sched/core.c:6388 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6696 irqentry_exit+0x31/0x80 kernel/entry/common.c:428 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0010:write_comp_data kernel/kcov.c:221 [inline] RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x1c/0x70 kernel/kcov.c:287 Code: d8 20 48 89 10 5b c3 0f 1f 80 00 00 00 00 41 89 f8 bf 03 00 00 00 4c 8b 14 24 89 f1 65 48 8b 34 25 00 70 02 00 e8 74 f9 ff ff <84> c0 74 4b 48 8b 86 88 15 00 00 8b b6 84 15 00 00 48 8b 10 48 c1 RSP: 0018:ffffc9000271f9c8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000200000 RCX: 0000000000200000 RDX: 0000000000000000 RSI: ffff88807cd39d00 RDI: 0000000000000003 RBP: ffff888019d70025 R08: 0000000000200000 R09: ffff88801ba19c58 R10: ffffffff81d62df9 R11: 0000000000000000 R12: 5e38b2550b4487b7 R13: ffff888019d70029 R14: fefefefefefefeff R15: 00000003fcf18e9c link_path_walk.part.0+0x6f9/0xf70 fs/namei.c:2357 link_path_walk fs/namei.c:2271 [inline] path_lookupat+0xc8/0x860 fs/namei.c:2498 filename_lookup+0x1c6/0x590 fs/namei.c:2528 vfs_statx+0x148/0x390 fs/stat.c:228 vfs_fstatat+0x8c/0xb0 fs/stat.c:255 __do_sys_newfstatat+0x91/0x110 fs/stat.c:425 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f3bcfd251da RSP: 002b:00007fff81fc1868 EFLAGS: 00000246 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 0000560027e556a0 RCX: 00007f3bcfd251da RDX: 00007fff81fc1878 RSI: 0000560027e437ed RDI: 00000000ffffff9c RBP: 0000560028dd96e8 R08: 0000000008ee6341 R09: 00007fff81fe1080 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000001 R14: 0000000000000000 R15: 00007fff81fc1878 </TASK> rcu: rcu_preempt kthread timer wakeup didn't happen for 10536 jiffies! g6633 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=4303 rcu: rcu_preempt kthread starved for 10537 jiffies! g6633 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 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:28728 pid: 16 ppid: 2 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:5073 [inline] __schedule+0xa9a/0x4cc0 kernel/sched/core.c:6388 schedule+0xd2/0x1f0 kernel/sched/core.c:6460 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1971 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2144 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 </TASK> rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 3854 Comm: syz-executor.2 Not tainted 5.18.0-rc2-syzkaller-00351-ga2c29ccd9477 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1e6/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:490 print_other_cpu_stall kernel/rcu/tree_stall.h:595 [inline] check_cpu_stall kernel/rcu/tree_stall.h:741 [inline] rcu_pending kernel/rcu/tree.c:3923 [inline] rcu_sched_clock_irq+0x1f7c/0x2150 kernel/rcu/tree.c:2625 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:243 tick_sched_timer+0xee/0x120 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0010:__mnt_want_write+0xdd/0x2e0 fs/namespace.c:348 Code: 00 02 00 00 89 de e8 02 83 9d ff 85 db 74 42 48 b8 00 00 00 00 00 fc ff df 4d 89 ec 49 c1 ec 03 49 01 c4 e8 c5 80 9d ff f3 90 <41> 0f b6 04 24 84 c0 74 08 3c 03 0f 8e 99 01 00 00 8b 5d 10 31 ff RSP: 0018:ffffc9000265fa10 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000000000 RDX: ffff888047ab9d00 RSI: ffffffff81db9abb RDI: 0000000000000003 RBP: ffff888077e853a0 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff81db9ae0 R11: 0000000000000001 R12: ffffed100efd0a76 R13: ffff888077e853b0 R14: ffff888077e853d0 R15: ffff888055036070 do_dentry_open+0xb6a/0x11e0 fs/open.c:793 do_open fs/namei.c:3476 [inline] path_openat+0x1c71/0x2910 fs/namei.c:3609 do_filp_open+0x1aa/0x400 fs/namei.c:3636 do_sys_openat2+0x16d/0x4c0 fs/open.c:1213 do_sys_open fs/open.c:1229 [inline] __do_sys_openat fs/open.c:1245 [inline] __se_sys_openat fs/open.c:1240 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1240 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fdbb34890e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdbb4502168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fdbb359bf60 RCX: 00007fdbb34890e9 RDX: 0000000000000002 RSI: 0000000020000340 RDI: 0000000000000003 RBP: 00007fdbb34e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdbb3acfb1f R14: 00007fdbb4502300 R15: 0000000000022000 </TASK> ---------------- Code disassembly (best guess): 0: d8 20 fsubs (%rax) 2: 48 89 10 mov %rdx,(%rax) 5: 5b pop %rbx 6: c3 retq 7: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) e: 41 89 f8 mov %edi,%r8d 11: bf 03 00 00 00 mov $0x3,%edi 16: 4c 8b 14 24 mov (%rsp),%r10 1a: 89 f1 mov %esi,%ecx 1c: 65 48 8b 34 25 00 70 mov %gs:0x27000,%rsi 23: 02 00 25: e8 74 f9 ff ff callq 0xfffff99e * 2a: 84 c0 test %al,%al <-- trapping instruction 2c: 74 4b je 0x79 2e: 48 8b 86 88 15 00 00 mov 0x1588(%rsi),%rax 35: 8b b6 84 15 00 00 mov 0x1584(%rsi),%esi 3b: 48 8b 10 mov (%rax),%rdx 3e: 48 rex.W 3f: c1 .byte 0xc1