Re: [PATCH] exit: skip IRQ disabled warning during power off

From: Breno Leitao
Date: Fri Apr 04 2025 - 11:16:35 EST

On Fri, Apr 04, 2025 at 04:16:24PM +0200, Oleg Nesterov wrote:
> On 04/04, Breno Leitao wrote:
> >
> > [ 254.474273] reboot: Power down
> > [ 254.479332] ------------[ cut here ]------------
> > [ 254.479934] WARNING: CPU: 0 PID: 1 at kernel/exit.c:881 do_exit (kernel/exit.c:881)
> ^^^^^^
> confused... so it seems that the init task does
> sys_reboot(LINUX_REBOOT_CMD_POWER_OFF) and exits?
>
> But if the init task exits for any reason it should trigger
>
> if (unlikely(is_global_init(tsk)))
> panic("Attempted to kill init! exitcode=0x%08x\n"

That is showing up later (sorry for not decoding it, but I don't think
it is super important)


[ 64.447039] ACPI: PM: Preparing to enter system sleep state S5
[ 64.454964] reboot: Power down
[ 64.460014] ------------[ cut here ]------------
[ 64.460597] WARNING: CPU: 0 PID: 1 at kernel/exit.c:881 do_exit+0xd0/0x2470
[ 64.461600] Modules linked in: evdev(E) serio_raw(E) button(E) virtio_mmio(E) 9pnet_virtio(E) 9p(E) 9pnet(E) netfs(E)
[ 64.462929] CPU: 0 UID: 0 PID: 1 Comm: virtme-ng-init Tainted: G E N 6.13.0-rc7-next-20250117-upstream #45
[ 64.464075] Tainted: [E]=UNSIGNED_MODULE, [N]=TEST
[ 64.464683] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 64.465960] RIP: 0010:do_exit+0xd0/0x2470
[ 64.466427] Code: 00 00 45 31 f6 f7 c3 00 02 00 00 41 0f 94 c6 48 c7 c7 48 8b 5d 87 44 89 f6 31 d2 31 c9 e8 c8 c5 41 00 f7 c3 00 02 00 00 75 02 <0f> 0b 48 c7 c7 78 8b 5d 87 44 89 f6 31 d2 31 c9 e8 ab c5 41 00 48
[ 64.468353] RSP: 0018:ffa000000001fb80 EFLAGS: 00010046
[ 64.468949] RAX: b246b26687739d00 RBX: 0000000000000016 RCX: 0000000000000000
[ 64.469832] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff875d8b48
[ 64.470648] RBP: ffa000000001fd10 R08: dffffc0000000000 R09: 1ffffffff13312b6
[ 64.471451] R10: dffffc0000000000 R11: fffffbfff13312b7 R12: 000000004321fedc
[ 64.472320] R13: dffffc0000000000 R14: 0000000000000001 R15: dffffc0000000000
[ 64.473200] FS: 00007ff47a8a0780(0000) GS:ff110004c6000000(0000) knlGS:0000000000000000
[ 64.474141] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 64.474841] CR2: 00007f4eb4ba1648 CR3: 000000010dcde004 CR4: 0000000000771ef0
[ 64.475667] PKRU: 55555554
[ 64.476058] Call Trace:
[ 64.476360] <TASK>
[ 64.476907] ? __warn+0x130/0x500
[ 64.477358] ? do_exit+0xd0/0x2470
[ 64.477794] ? do_exit+0xd0/0x2470
[ 64.478210] ? report_bug+0x1bd/0x400
[ 64.478675] ? handle_bug+0x63/0x90
[ 64.479082] ? exc_invalid_op+0x1a/0x50
[ 64.479498] ? asm_exc_invalid_op+0x1a/0x20
[ 64.479976] ? do_exit+0xd0/0x2470
[ 64.480457] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.481071] ? __rcu_read_unlock+0xf3/0x630
[ 64.481513] ? atomic_notifier_call_chain+0x26/0x110
[ 64.482075] ? __pfx_do_exit+0x10/0x10
[ 64.482594] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.483493] ? native_machine_shutdown+0x12c/0x1f0
[ 64.484248] ? atomic_notifier_call_chain+0x26/0x110
[ 64.484854] __x64_sys_reboot+0x339/0x340
[ 64.485275] ? __pfx___x64_sys_reboot+0x10/0x10
[ 64.485986] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.486564] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.487118] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.487668] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.488211] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.488772] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.489317] ? do_syscall_64+0x77/0x260
[ 64.489902] do_syscall_64+0xd6/0x260
[ 64.490349] ? exc_page_fault+0xc8/0x130
[ 64.490811] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 64.491332] RIP: 0033:0x7ff47a704a27
[ 64.491789] Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 89 fa be 69 19 12 28 bf ad de e1 fe b8 a9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 c1 43 0f 00 f7 d8 64 89 02 b8
[ 64.493809] RSP: 002b:00007ffed123b8e8 EFLAGS: 00000217 ORIG_RAX: 00000000000000a9
[ 64.494601] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007ff47a704a27
[ 64.495454] RDX: 000000004321fedc RSI: 0000000028121969 RDI: 00000000fee1dead
[ 64.496254] RBP: 000000000000000a R08: 000056492265c690 R09: 0000000000000000
[ 64.497111] R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000000011
[ 64.498048] R13: 00007ffed123bca8 R14: 000056492263c28c R15: 000000000000000a
[ 64.498940] </TASK>
[ 64.499238] irq event stamp: 1436466
[ 64.499677] hardirqs last enabled at (1436465): [<ffffffff847d9edb>] _raw_spin_unlock_irqrestore+0x8b/0x150
[ 64.500762] hardirqs last disabled at (1436466): [<ffffffff81369164>] native_machine_shutdown+0xc4/0x1f0
[ 64.501815] softirqs last enabled at (1436194): [<ffffffff8142617f>] handle_softirqs+0xa0f/0xb80
[ 64.502716] softirqs last disabled at (1436175): [<ffffffff81426532>] __irq_exit_rcu+0xc2/0x200
[ 64.503728] ---[ end trace 0000000000000000 ]---
[ 64.504458] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
[ 64.505337] CPU: 0 UID: 0 PID: 1 Comm: virtme-ng-init Tainted: G W E N 6.13.0-rc7-next-20250117-upstream #45
[ 64.506249] Tainted: [W]=WARN, [E]=UNSIGNED_MODULE, [N]=TEST
[ 64.506874] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 64.507881] Call Trace:
[ 64.508136] <TASK>
[ 64.508452] dump_stack_lvl+0x8e/0x1b0
[ 64.508975] ? __pfx_dump_stack_lvl+0x10/0x10
[ 64.509448] ? __pfx__printk+0x10/0x10
[ 64.509891] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.510363] panic+0x256/0x550
[ 64.510745] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.511209] ? __pfx_panic+0x10/0x10
[ 64.511665] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.512269] ? _raw_spin_unlock_irq+0x66/0x80
[ 64.512757] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.513200] ? seccomp_filter_release+0xf9/0x130
[ 64.513696] do_exit+0x623/0x2470
[ 64.514073] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.514523] ? __rcu_read_unlock+0xf3/0x630
[ 64.514937] ? __pfx_do_exit+0x10/0x10
[ 64.515342] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.515949] ? native_machine_shutdown+0x12c/0x1f0
[ 64.516437] ? atomic_notifier_call_chain+0x26/0x110
[ 64.516941] __x64_sys_reboot+0x339/0x340
[ 64.517302] ? __pfx___x64_sys_reboot+0x10/0x10
[ 64.517793] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.518288] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.518775] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.519363] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.519889] ? __pfx_ftrace_likely_update+0x10/0x10
[ 64.520350] ? srso_alias_return_thunk+0x5/0xfbef5
[ 64.520828] ? do_syscall_64+0x77/0x260
[ 64.521192] do_syscall_64+0xd6/0x260
[ 64.521537] ? exc_page_fault+0xc8/0x130
[ 64.521922] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 64.522510] RIP: 0033:0x7ff47a704a27
[ 64.522918] Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 89 fa be 69 19 12 28 bf ad de e1 fe b8 a9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 c1 43 0f 00 f7 d8 64 89 02 b8
[ 64.524412] RSP: 002b:00007ffed123b8e8 EFLAGS: 00000217 ORIG_RAX: 00000000000000a9
[ 64.525153] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007ff47a704a27
[ 64.525966] RDX: 000000004321fedc RSI: 0000000028121969 RDI: 00000000fee1dead
[ 64.526651] RBP: 000000000000000a R08: 000056492265c690 R09: 0000000000000000
[ 64.527392] R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000000011
[ 64.528059] R13: 00007ffed123bca8 R14: 000056492263c28c R15: 000000000000000a
[ 64.528847] </TASK>
[ 64.529287] Kernel Offset: disabled
[ 64.530125] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000 ]---

>
> below?
>
> OK, it can be multi-threaded, but still this look like we have more
> problems than just WARN_ON(irqs_disabled()).
>
> > When pid=1 is being killed, then synchronize_group_exit() will be called
> > with irq enabled (as shown by the warning above),
>
> Hmm. synchronize_group_exit() is called right after WARN_ON(irqs_disabled())
> you observe, WARN_ON() won't enable irqs?

That is Mateusz raised as well. We are discussing it on the other
thread. TL;DR: Is that warning wrongly placed, since IRQs will be
enabled after synchronize_group_exit()?!

Let's move this discussion to that thread, please.