linux-kernel - Re: [PATCH v4 0/2] kexec, panic: Making crash

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Message-ID: <Yszgzwnk2Y+4ki58@MiWiFi-R3L-srv>
Date:   Tue, 12 Jul 2022 10:47:43 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Valentin Schneider <vschneid@...hat.com>
Cc:     kexec@...ts.infradead.org, linux-rt-users@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Eric Biederman <ebiederm@...ssion.com>,
        Arnd Bergmann <arnd@...db.de>, Petr Mladek <pmladek@...e.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Juri Lelli <jlelli@...hat.com>,
        "Luis Claudio R. Goncalves" <lgoncalv@...hat.com>,
        akpm@...ux-foundation.org
Subject: Re: [PATCH v4 0/2] kexec, panic: Making crash_kexec() NMI safe

Hi,

On 06/30/22 at 11:32pm, Valentin Schneider wrote:
> Hi folks,
> 
> Here's ~v3~ v4 where we now completely get rid of kexec_mutex.
> 
> o Patch 1 makes sure all kexec_mutex acquisitions are trylocks. This prevents
>   having to add any while(atomic_cmpxchg()) loops which I'd really hate to see
>   here. If that can't be done then I think we're better off with the combined
>   mutex+atomic var approach.
> o Patch 2 does the mutex -> atomic var switch.

This series looks good, has it been taken into any tree?

Thanks
Baoquan

> 
> Revisions
> =========
> 
> v3 -> v4
> ++++++++
> 
> o Someone forgot to Cc LKML on v3...
> 
> v2 -> v3
> ++++++++
> 
> o Dropped kexec_mutex entirely and made the atomic variable the one true lock
>   for kexec (Eric)
> 
> v1 -> v2
> ++++++++
> 
> o Changed from Peterson-like synchronization to simpler atomic_cmpxchg
>   (Petr)
> o Slightly reworded changelog
> o Added Fixes: tag. Technically should be up to since kexec can happen
>   in an NMI, but that isn't such a clear target
> 
> Cheers,
> Valentin
> 
> Valentin Schneider (2):
>   kexec: Turn all kexec_mutex acquisitions into trylocks
>   panic, kexec: Make __crash_kexec() NMI safe
> 
>  include/linux/kexec.h   |  2 +-
>  kernel/kexec.c          | 11 ++++-------
>  kernel/kexec_core.c     | 28 ++++++++++++++++------------
>  kernel/kexec_file.c     |  4 ++--
>  kernel/kexec_internal.h | 15 ++++++++++++++-
>  kernel/ksysfs.c         |  7 ++++++-
>  6 files changed, 43 insertions(+), 24 deletions(-)
> 
> --
> 2.31.1
>