From: Steven Rostedt <rostedt@goodmis.org>
To: Petr Mladek <pmladek@suse.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
Evan Green <evgreen@chromium.org>,
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Subject: Re: [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path
Date: Tue, 10 May 2022 13:20:15 -0400 [thread overview]
Message-ID: <20220510132015.38923cb2@gandalf.local.home> (raw)
In-Reply-To: <YnpOv4hAPV4b+6v4@alley>
On Tue, 10 May 2022 13:38:39 +0200
Petr Mladek <pmladek@suse.com> wrote:
> As already mentioned in the other reply, panic() sometimes stops
> the other CPUs using NMI, for example, see kdump_nmi_shootdown_cpus().
>
> Another situation is when the CPU using the lock ends in some
> infinite loop because something went wrong. The system is in
> an unpredictable state during panic().
>
> I am not sure if this is possible with the code under gsmi_dev.lock
> but such things really happen during panic() in other subsystems.
> Using trylock in the panic() code path is a good practice.
I believe that Peter Zijlstra had a special spin lock for NMIs or early
printk, where it would not block if the lock was held on the same CPU. That
is, if an NMI happened and paniced while this lock was held on the same
CPU, it would not deadlock. But it would block if the lock was held on
another CPU.
-- Steve
next prev parent reply other threads:[~2022-05-10 17:20 UTC|newest]
Thread overview: 183+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 22:48 [PATCH 00/30] The panic notifiers refactor Guilherme G. Piccoli
2022-04-27 22:48 ` [PATCH 01/30] x86/crash,reboot: Avoid re-disabling VMX in all CPUs on crash/restart Guilherme G. Piccoli
2022-05-09 12:32 ` Guilherme G. Piccoli
2022-05-09 15:52 ` Sean Christopherson
2022-05-10 20:11 ` Guilherme G. Piccoli
2022-04-27 22:48 ` [PATCH 02/30] ARM: kexec: Disable IRQs/FIQs also on crash CPUs shutdown path Guilherme G. Piccoli
2022-04-29 16:26 ` Michael Kelley (LINUX)
2022-04-29 18:20 ` Marc Zyngier
2022-04-29 21:38 ` Guilherme G. Piccoli
2022-04-29 21:45 ` Russell King (Oracle)
2022-04-29 21:56 ` Guilherme G. Piccoli
2022-04-29 22:00 ` Marc Zyngier
2022-04-27 22:48 ` [PATCH 03/30] notifier: Add panic notifiers info and purge trailing whitespaces Guilherme G. Piccoli
2022-04-27 22:48 ` [PATCH 04/30] firmware: google: Convert regular spinlock into trylock on panic path Guilherme G. Piccoli
2022-05-03 18:03 ` Evan Green
2022-05-03 19:12 ` Guilherme G. Piccoli
2022-05-03 21:56 ` Evan Green
2022-05-04 12:45 ` Guilherme G. Piccoli
2022-05-10 11:38 ` Petr Mladek
2022-05-10 13:04 ` Guilherme G. Piccoli
2022-05-10 17:20 ` Steven Rostedt [this message]
2022-05-10 19:40 ` John Ogness
2022-05-11 11:13 ` Petr Mladek
2022-04-27 22:48 ` [PATCH 05/30] misc/pvpanic: " Guilherme G. Piccoli
2022-05-10 12:14 ` Petr Mladek
2022-05-10 13:00 ` Guilherme G. Piccoli
2022-05-17 10:58 ` Petr Mladek
2022-05-17 13:03 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 06/30] soc: bcm: brcmstb: Document panic notifier action and remove useless header Guilherme G. Piccoli
2022-05-02 15:38 ` Florian Fainelli
2022-05-02 15:47 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 07/30] mips: ip22: Reword PANICED to PANICKED " Guilherme G. Piccoli
2022-05-04 20:32 ` Thomas Bogendoerfer
2022-05-04 21:26 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 08/30] powerpc/setup: Refactor/untangle panic notifiers Guilherme G. Piccoli
2022-05-05 18:55 ` Hari Bathini
2022-05-05 19:28 ` Guilherme G. Piccoli
2022-05-09 12:50 ` Guilherme G. Piccoli
2022-05-10 13:53 ` Michael Ellerman
2022-05-10 14:10 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 09/30] coresight: cpu-debug: Replace mutex with mutex_trylock on panic notifier Guilherme G. Piccoli
2022-04-28 8:11 ` Suzuki K Poulose
2022-04-29 14:01 ` Guilherme G. Piccoli
2022-05-09 13:09 ` Guilherme G. Piccoli
2022-05-09 16:14 ` Suzuki K Poulose
2022-05-09 16:26 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 10/30] alpha: Clean-up the panic notifier code Guilherme G. Piccoli
2022-05-09 14:13 ` Guilherme G. Piccoli
2022-05-10 14:16 ` Petr Mladek
2022-05-11 20:10 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 11/30] um: Improve panic notifiers consistency and ordering Guilherme G. Piccoli
2022-04-28 8:30 ` Johannes Berg
2022-04-29 15:46 ` Guilherme G. Piccoli
2022-05-10 14:28 ` Petr Mladek
2022-05-11 20:22 ` Guilherme G. Piccoli
2022-05-13 14:44 ` Johannes Berg
2022-05-15 22:12 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 12/30] parisc: Replace regular spinlock with spin_trylock on panic path Guilherme G. Piccoli
2022-04-28 16:55 ` Helge Deller
2022-04-29 14:34 ` Guilherme G. Piccoli
2022-05-23 20:40 ` Guilherme G. Piccoli
2022-05-23 21:31 ` Helge Deller
2022-05-23 21:55 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 13/30] s390/consoles: Improve panic notifiers reliability Guilherme G. Piccoli
2022-04-29 18:46 ` Heiko Carstens
2022-04-29 19:31 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 14/30] panic: Properly identify the panic event to the notifiers' callbacks Guilherme G. Piccoli
2022-05-10 15:16 ` Petr Mladek
2022-05-10 16:16 ` Guilherme G. Piccoli
2022-05-17 13:11 ` Petr Mladek
2022-05-17 15:19 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 15/30] bus: brcmstb_gisb: Clean-up panic/die notifiers Guilherme G. Piccoli
2022-05-02 15:38 ` Florian Fainelli
2022-05-02 15:50 ` Guilherme G. Piccoli
2022-05-10 15:28 ` Petr Mladek
2022-05-17 15:32 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 16/30] drivers/hv/vmbus, video/hyperv_fb: Untangle and refactor Hyper-V panic notifiers Guilherme G. Piccoli
2022-04-29 17:16 ` Michael Kelley (LINUX)
2022-04-29 22:35 ` Guilherme G. Piccoli
2022-05-03 18:13 ` Michael Kelley (LINUX)
2022-05-03 18:57 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 17/30] tracing: Improve panic/die notifiers Guilherme G. Piccoli
2022-04-29 9:22 ` Sergei Shtylyov
2022-04-29 13:23 ` Steven Rostedt
2022-04-29 13:46 ` Guilherme G. Piccoli
2022-04-29 13:56 ` Steven Rostedt
2022-04-29 14:44 ` Guilherme G. Piccoli
2022-05-11 11:45 ` Petr Mladek
2022-05-17 15:33 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 18/30] notifier: Show function names on notifier routines if DEBUG_NOTIFIERS is set Guilherme G. Piccoli
2022-04-28 1:01 ` Xiaoming Ni
2022-04-29 19:38 ` Guilherme G. Piccoli
2022-05-10 17:29 ` Steven Rostedt
2022-05-16 16:14 ` Guilherme G. Piccoli
2022-04-29 16:27 ` Michael Kelley (LINUX)
2022-04-27 22:49 ` [PATCH 19/30] panic: Add the panic hypervisor notifier list Guilherme G. Piccoli
2022-04-29 17:30 ` Michael Kelley (LINUX)
2022-04-29 18:04 ` Guilherme G. Piccoli
2022-05-03 17:44 ` Michael Kelley (LINUX)
2022-05-03 17:56 ` Guilherme G. Piccoli
2022-05-16 14:01 ` Petr Mladek
2022-05-16 15:06 ` Guilherme G. Piccoli
2022-05-16 16:02 ` Evan Green
2022-05-17 13:28 ` Petr Mladek
2022-05-17 16:37 ` Guilherme G. Piccoli
2022-05-18 7:33 ` Petr Mladek
2022-05-18 13:24 ` Guilherme G. Piccoli
2022-05-17 13:57 ` Petr Mladek
2022-05-17 16:42 ` Guilherme G. Piccoli
2022-05-18 7:38 ` Petr Mladek
2022-05-18 13:09 ` Guilherme G. Piccoli
2022-05-18 22:17 ` Scott Branden
2022-05-19 12:19 ` Guilherme G. Piccoli
2022-05-19 19:20 ` Scott Branden
2022-05-23 14:56 ` Guilherme G. Piccoli
2022-05-24 8:04 ` Petr Mladek
2022-05-18 7:58 ` Petr Mladek
2022-05-18 13:16 ` Guilherme G. Piccoli
2022-05-19 7:03 ` Petr Mladek
2022-05-19 12:07 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 20/30] panic: Add the panic informational " Guilherme G. Piccoli
2022-04-27 23:49 ` Paul E. McKenney
2022-04-28 8:14 ` Suzuki K Poulose
2022-04-29 14:50 ` Guilherme G. Piccoli
2022-05-16 14:11 ` Petr Mladek
2022-05-16 14:28 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 21/30] panic: Introduce the panic pre-reboot " Guilherme G. Piccoli
2022-04-28 14:13 ` Alex Elder
2022-04-28 16:26 ` Corey Minyard
2022-04-29 15:18 ` Guilherme G. Piccoli
2022-04-29 16:04 ` Max Filippov
2022-04-29 19:34 ` Guilherme G. Piccoli
2022-05-16 14:33 ` Petr Mladek
2022-05-16 16:05 ` Guilherme G. Piccoli
2022-05-16 16:18 ` Luck, Tony
2022-05-16 16:33 ` Guilherme G. Piccoli
2022-05-17 14:11 ` Petr Mladek
2022-05-17 16:45 ` Guilherme G. Piccoli
2022-05-17 17:02 ` Luck, Tony
2022-05-17 18:12 ` Guilherme G. Piccoli
2022-05-17 19:07 ` Luck, Tony
2022-04-27 22:49 ` [PATCH 22/30] panic: Introduce the panic post-reboot " Guilherme G. Piccoli
2022-05-09 14:16 ` Guilherme G. Piccoli
2022-05-11 16:45 ` Heiko Carstens
2022-05-11 19:58 ` Guilherme G. Piccoli
2022-05-16 14:45 ` Petr Mladek
2022-05-16 16:08 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 23/30] printk: kmsg_dump: Introduce helper to inform number of dumpers Guilherme G. Piccoli
2022-05-10 17:40 ` Steven Rostedt
2022-05-11 20:03 ` Guilherme G. Piccoli
2022-05-16 14:50 ` Petr Mladek
2022-05-16 16:09 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 24/30] panic: Refactor the panic path Guilherme G. Piccoli
2022-04-28 0:28 ` Randy Dunlap
2022-04-29 16:04 ` Guilherme G. Piccoli
2022-05-09 14:25 ` Guilherme G. Piccoli
2022-04-29 17:53 ` Michael Kelley (LINUX)
2022-04-29 20:38 ` Guilherme G. Piccoli
2022-05-03 17:31 ` Michael Kelley (LINUX)
2022-05-03 18:06 ` Guilherme G. Piccoli
2022-05-09 15:16 ` d.hatayama
2022-05-09 16:39 ` Guilherme G. Piccoli
2022-05-12 14:03 ` Petr Mladek
2022-05-15 22:47 ` Guilherme G. Piccoli
2022-05-16 10:21 ` Petr Mladek
2022-05-16 16:32 ` Guilherme G. Piccoli
2022-05-19 23:45 ` Baoquan He
2022-05-20 11:23 ` Guilherme G. Piccoli
2022-05-24 8:01 ` Petr Mladek
2022-05-24 10:18 ` Baoquan He
2022-05-24 8:32 ` Baoquan He
2022-05-24 14:44 ` Eric W. Biederman
2022-05-26 16:25 ` Guilherme G. Piccoli
2022-06-14 14:36 ` Petr Mladek
2022-06-15 9:36 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 25/30] panic, printk: Add console flush parameter and convert panic_print to a notifier Guilherme G. Piccoli
2022-05-16 14:56 ` Petr Mladek
2022-05-16 16:11 ` Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 26/30] Drivers: hv: Do not force all panic notifiers to execute before kdump Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 27/30] powerpc: " Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 28/30] panic: Unexport crash_kexec_post_notifiers Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 29/30] powerpc: ps3, pseries: Avoid duplicate call to kmsg_dump() on panic Guilherme G. Piccoli
2022-04-27 22:49 ` [PATCH 30/30] um: Avoid duplicate call to kmsg_dump() Guilherme G. Piccoli
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