Re: [linux-pm] [PATCH] hibernation should work ok with memory hotplug

KAMEZAWA Hiroyuki
2008-11-06T02:13:32Z

On Thu, 06 Nov 2008 13:03:06 +1100
Nigel Cunningham <ncunningham@crca.org.au> wrote:

> Hi.
>
> On Thu, 2008-11-06 at 09:53 +0900, KAMEZAWA Hiroyuki wrote:
> > On Wed, 05 Nov 2008 16:28:01 -0800
> > Dave Hansen <dave@linux.vnet.ibm.com> wrote:
> >
> > > On Thu, 2008-11-06 at 09:14 +0900, KAMEZAWA Hiroyuki wrote:
> > > > Ok, please consider "when memory hotplug happens."
> > > >
> > > > In general, it happens when
> > > > 1. memory is inserted to slot.
> > > > 2. the firmware notifes the system to enable already inserted memory.
> > > >
> > > > To trigger "1", you have to open cover of server/pc. Do you open pc while the system
> > > > starts hibernation ? for usual people, no.
> > >
> > > You're right, this won't happen very often. We're trying to close a
> > > theoretical hole that hasn't ever been observed in practice. But, we
> > > don't exactly leave races in code just because we haven't observed them.
> > > I think this is a classic race.
> > >
> > > If we don't close it now, then someone doing some really weirdo hotplug
> > > is going to run into it at some point. Who knows what tomorrow's
> > > hardware/firmware will do?
> > >
> > Hmm, people tend to make crazy hardware, oh yes. the pc may fly in the sky with rocket engine.
>
> It doesn't even have to be crazy. Just imagine someone bumping a button
> on the case while plugging in the memory and that button being
> configured to make the machine hibernate.
>
please don't start hibernation if cover is open....(if you can)

Thanks,
-Kame