Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: CONFIG_NUMA breaks hibernation on x86-32 with PAE | Date | Tue, 11 Nov 2008 17:47:27 +0100 |
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On Tuesday, 11 of November 2008, Pavel Machek wrote: > > > > > It is. However, the problem is 100% reproducible on any 32-bit single-node > > > > system with CONFIG_NUMA set, from what I can tell. > > > > > > > > It doesn't happen if the kernel is booted with highmem=0, so it looks like > > > > the code that saves highmem causes the problem to happen. However, this > > > > same code works well for all of the !CONFIG_NUMA cases and practically only > > > > the only non-open-coded it uses is kmap_atomic(). > > > > > > > > > One possibility would be to bisect if it ever worked? > > > > > > > > Not sure it did, probably not. :-( > > > > > > Well, interesting point would be just before this commit: > > > > > > > > > commit 8357376d3df21b7d6f857931a57ac50da9c66e26 > > > tree daf2c369e9b79d24c1666323b3ae75189e482a4a > > > parent bf73bae6ba0dc4bd4f1e570feb34a06b72725af6 > > > author Rafael J. Wysocki <rjw@sisk.pl> Wed, 06 Dec 2006 20:34:18 -0800 > > > committer Linus Torvalds <torvalds@woody.osdl.org> Thu, 07 Dec 2006 > > > 08:39:27 -0800 > > > > > > [PATCH] swsusp: Improve handling of highmem > > > > > > Currently swsusp saves the contents of highmem pages by copying > > > them to the > > > normal zone which is quite inefficient (eg. it requires two > > > normal pages > > > to be used for saving one highmem page). This may be improved by > > > using > > > highmem for saving the contents of saveable highmem pages. > > > > > > ...highmem handling was way simpler in those good old days ;-) > > > > Please stop kidding, this is a serious issue. > > > > The hibernation code _works_ with all kinds of highmem when CONFIG_NUMA is > > unset. > > 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.
> 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.
Thanks, Rafael
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