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From: Philipp Rudo <prudo@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
	linux-kernel@vger.kernel.org, ribalda@google.com,
	zwisler@google.com, robdclark@gmail.com,
	Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org
Subject: Re: [PATCH RFC] kexec: Freeze processes before kexec
Date: Thu, 17 Nov 2022 16:46:12 +0100	[thread overview]
Message-ID: <20221117164612.65832e37@rotkaeppchen> (raw)
In-Reply-To: <20221116151610.7294a9e8@gandalf.local.home>

Hi Steve,

On Wed, 16 Nov 2022 15:16:10 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Wed, 16 Nov 2022 19:56:24 +0000
> "Joel Fernandes (Google)" <joel@joelfernandes.org> wrote:
> 
> > --- a/kernel/kexec_core.c
> > +++ b/kernel/kexec_core.c
> > @@ -1175,6 +1175,12 @@ int kernel_kexec(void)
> >  	} else
> >  #endif
> >  	{
> > +		error = freeze_processes();
> > +		if (error) {
> > +			error = -EBUSY;
> > +			goto Unlock;
> > +		}  
> 
> If this is the path of a kernel panic, do we really want to check the
> return error of freeze_processes()? We are panicing, there's not much more
> we can do.

kernel_kexec isn't called during panic. We don't need to worry about it
here.

Having that said I think this is a problem in the device driver _not_
in kexec. In my opinion it's the job of the driver to prevent such
races during shutdown.

Thanks
Philipp


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

WARNING: multiple messages have this Message-ID (diff)
From: Philipp Rudo <prudo@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
	linux-kernel@vger.kernel.org, ribalda@google.com,
	zwisler@google.com, robdclark@gmail.com,
	Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org
Subject: Re: [PATCH RFC] kexec: Freeze processes before kexec
Date: Thu, 17 Nov 2022 16:46:12 +0100	[thread overview]
Message-ID: <20221117164612.65832e37@rotkaeppchen> (raw)
In-Reply-To: <20221116151610.7294a9e8@gandalf.local.home>

Hi Steve,

On Wed, 16 Nov 2022 15:16:10 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Wed, 16 Nov 2022 19:56:24 +0000
> "Joel Fernandes (Google)" <joel@joelfernandes.org> wrote:
> 
> > --- a/kernel/kexec_core.c
> > +++ b/kernel/kexec_core.c
> > @@ -1175,6 +1175,12 @@ int kernel_kexec(void)
> >  	} else
> >  #endif
> >  	{
> > +		error = freeze_processes();
> > +		if (error) {
> > +			error = -EBUSY;
> > +			goto Unlock;
> > +		}  
> 
> If this is the path of a kernel panic, do we really want to check the
> return error of freeze_processes()? We are panicing, there's not much more
> we can do.

kernel_kexec isn't called during panic. We don't need to worry about it
here.

Having that said I think this is a problem in the device driver _not_
in kexec. In my opinion it's the job of the driver to prevent such
races during shutdown.

Thanks
Philipp


  parent reply	other threads:[~2022-11-17 15:47 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-16 19:56 [PATCH RFC] kexec: Freeze processes before kexec Joel Fernandes (Google)
2022-11-16 19:56 ` Joel Fernandes (Google)
2022-11-16 20:16 ` Steven Rostedt
2022-11-16 20:16   ` Steven Rostedt
2022-11-16 21:07   ` Joel Fernandes
2022-11-16 21:07     ` Joel Fernandes
2022-11-17 15:46   ` Philipp Rudo [this message]
2022-11-17 15:46     ` Philipp Rudo
2022-11-17 16:07     ` Joel Fernandes
2022-11-17 16:07       ` Joel Fernandes

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