Hi Guys, I just found that sometimes v4.12-rc6 kernel hang happens during booting, please see the following stack trace: [ OK ] Listening on LVM2 poll daemon socket. INFO: rcu_preempt detected stalls on CPUs/tasks: 0-...: (0 ticks this GP) idle=732/140000000000000/0 softirq=1182/1186 fqs=8061 (detected by 1, t=16252 jiffies, g=86, c=85, q=3) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 1 Comm: systemd Not tainted 4.12.0-rc6 #305 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 task: ffff880234098040 task.stack: ffff8802340a0000 RIP: 0010:___slab_alloc+0x391/0x600 RSP: 0018:ffff8802340a7800 EFLAGS: 00000093 RAX: 0000000000000005 RBX: ffff880235410380 RCX: ffffffff9a36690e RDX: ffff88027ffdcd80 RSI: ffff880235403d00 RDI: 0000000000000000 RBP: ffff8802340a78c0 R08: 0000000000000000 R09: 0000000000000000 R10: ffff8802340a7800 R11: 0000000000000001 R12: 0000000001080020 R13: ffff880235403d00 R14: 0000000000000002 R15: ffff88027ffddb00 FS: 00007f00143ed8c0(0000) GS:ffff880236000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055d905dba758 CR3: 0000000231d99000 CR4: 00000000003406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? alloc_cpumask_var_node+0x3b/0x60 __slab_alloc.isra.65+0x61/0xa0 ? __slab_alloc.isra.65+0x61/0xa0 ? alloc_cpumask_var_node+0x3b/0x60 ? alloc_cpumask_var_node+0x3b/0x60 __kmalloc_node+0xe0/0x500 ? free_cpumask_var+0x9/0x10 ? kasan_slab_free+0x88/0xc0 alloc_cpumask_var_node+0x3b/0x60 alloc_cpumask_var+0xe/0x10 native_send_call_func_ipi+0x64/0x1e0 ? smp_stop_nmi_callback+0x180/0x180 ? __bitmap_and+0xd3/0x100 ? _find_next_bit+0x31/0xa0 smp_call_function_many+0x25c/0x330 ? arch_unregister_cpu+0x40/0x40 ? arch_unregister_cpu+0x40/0x40 ? ___slab_alloc+0x413/0x600 smp_call_function+0x3b/0x70 ? arch_unregister_cpu+0x40/0x40 on_each_cpu+0x2f/0xb0 ? ___slab_alloc+0x412/0x600 text_poke_bp+0xf0/0x130 ? poke_int3_handler+0x70/0x70 ? get_online_cpus+0x2e/0x80 ? ___slab_alloc+0x412/0x600 arch_jump_label_transform+0x111/0x1b0 ? bug_at+0x30/0x30 ? check_chain_key+0x147/0x1f0 ? mark_lock+0xc9/0x7b0 __jump_label_update+0xc2/0xe0 jump_label_update+0xbc/0x170 static_key_slow_inc+0xa9/0xc0 cpuset_css_online+0x95/0x6c0 online_css+0x51/0xf0 cgroup_apply_control_enable+0x349/0x4e0 cgroup_mkdir+0x3db/0x550 ? cgroup_destroy_locked+0x1f0/0x1f0 kernfs_iop_mkdir+0xb1/0xe0 vfs_mkdir+0x1f1/0x2c0 SyS_mkdir+0x16f/0x1a0 ? SyS_mkdirat+0x1b0/0x1b0 ? trace_hardirqs_on_caller+0x1b2/0x2a0 ? trace_hardirqs_on_thunk+0x1a/0x1c entry_SYSCALL_64_fastpath+0x23/0xc2 RIP: 0033:0x7f00129e2727 RSP: 002b:00007ffd7c8bbad8 EFLAGS: 00000246 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: ffffffff9a159ce8 RCX: 00007f00129e2727 RDX: 00007ffd7c8bb9a0 RSI: 00000000000001ed RDI: 000055d905cf8eb0 RBP: ffff8802340a7f98 R08: 000000000000fefc R09: 0000000000000000 R10: 000055d905cf8ec0 R11: 0000000000000246 R12: ffffffff9a728503 R13: ffff8802340a7f78 R14: 000055d905d08090 R15: 000055d905d08388 ? __this_cpu_preempt_check+0x13/0x20 ? trace_hardirqs_off_caller+0xe8/0x160 Code: c7 48 8b bd 70 ff ff ff 4c 8d bc 38 00 1b 00 00 45 3b 77 08 0f 82 56 02 00 00 49 8b 17 44 8b 65 88 48 85 d2 75 1a e9 81 00 00 00 <45> 3b 77 18 49 8d 47 10 72 68 48 8b 10 49 89 c7 48 85 d2 74 6c Thanks, Ming Lei -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>