linux-kernel - Re: [patch] add kdump_after

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Message-ID: <20070726153440.GA19095@suse.de>
Date:	Thu, 26 Jul 2007 17:34:40 +0200
From:	Bernhard Walle <bwalle@...e.de>
To:	Vivek Goyal <vgoyal@...ibm.com>
Cc:	Takenori Nagano <t-nagano@...jp.nec.com>,
	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
	k-miyoshi@...jp.nec.com, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [patch] add kdump_after_notifier

* Vivek Goyal <vgoyal@...ibm.com> [2007-07-26 17:32]:
> On Thu, Jul 26, 2007 at 04:07:02PM +0200, Bernhard Walle wrote:
> > * Takenori Nagano <t-nagano@...jp.nec.com> [2007-07-19 14:15]:
> > > 
> > > In latest kernel, we can't use panic_notifier_list if kdump is enabled.
> > > panic_notifier_list is very useful function for debug, failover, etc...
> > > 
> > > So this patch adds a control file /proc/sys/kernel/dump_after_notifier
> > > and resolves a problem users can not use both kdump and panic_notifier_list
> > > at the same time.
> > > 
> > > kdump_after_notifier = 0
> > >  -> panic()
> > >     -> crash_kexec(NULL)
> > > 
> > > kdump_after_notifier = 1
> > >  -> panic()
> > >     -> atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
> > >     -> crash_kexec(NULL)
> > 
> > What's problematic about this patch? I also would like to see that
> > feature.
> 
> I would like to see the code which will get executed after panic and 
> before crash_kexec(). This potentially makes crash dump feature unreliable
> in the sense one can now register on panic_notifier_list and try to
> do whole lot of things and might get stuck there. After the system
> has crashed, one is not supposed to do a whole lot.

Of course, but that's why the patch doesn't change this by default but
gives the user the choice.


Thanks,
   Bernhard
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