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Date: Tue, 19 Jul 2011 19:52:13 +0100
From: Matthew Garrett <mjg@redhat.com>
To: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: "kexec@lists.infradead.org" <kexec@lists.infradead.org>,
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Subject: Re: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to
 kexec path
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On Tue, Jul 19, 2011 at 02:48:22PM -0400, Seiji Aguchi wrote:
> >How is this safe? What happens if there's a pstore access in process
> >when you hit this codepath?
> 
> This will never happen because pstore_kmsg_dump_in_interrupt() is called after machine_crash_shutdown().
> 
> Panicked cpu sends NMI to all other cpus in machine_crash_shutdown() and they stop.

And how does that handle the case where we're halfway through a pstore
access when the NMI arrives? ERST, at least, has a complex state 
machine. You can't guarantee what starting one transaction without 
completing one that was in process will do.

-- 
Matthew Garrett | mjg59@srcf.ucam.org