Re: CONFIG_NUMA breaks hibernation on x86-32 with PAE

From: Pavel Machek
Date: Wed Nov 12 2008 - 05:50:30 EST



> > > > Well, interesting point would be just before this commit:
> > > >
> > > >
> > > > commit 8357376d3df21b7d6f857931a57ac50da9c66e26
> > > > tree daf2c369e9b79d24c1666323b3ae75189e482a4a
> > > > parent bf73bae6ba0dc4bd4f1e570feb34a06b72725af6
> > > > author Rafael J. Wysocki <rjw@xxxxxxx> Wed, 06 Dec 2006 20:34:18 -0800
> > > > committer Linus Torvalds <torvalds@xxxxxxxxxxxxxx> Thu, 07 Dec 2006
> > > > 08:39:27 -0800
> > > >
> > > > [PATCH] swsusp: Improve handling of highmem
...
> > And it does not work with single highmem page when NUMA is set... I
> > went through the highmem saving code, and it depends on highmem not
> > changing from under it (right?) and is generally quite tricky ('if
> > they are both in highmem do this, else if one of them is do that, else
> > do something else')
>
> It actually is quite simple, if you know the idea.
>
> > and it changes page protections on the fly, etc.
>
> No, it doesn't do that, at least for pages it hasn't allocated itself. I don't
> think it changes anything like page protections at all, though.

safe_copy_page() seems to call kernel_map_pages() on s_page... which
is page from the system AFAICT...

> > I'm not saying the bug is in that code, but before that commit we had
> > very stupid --- but very robust -- code. I'll try if that one works
> > with config_numa, perhaps we can get some debug info that way.
>
> if you can do that, it actually may be valuable information.

So far I know that software suspend depends on !PAE in that old
version. If I only recalled why...
Pavel
--
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