linux-kernel - Re: Top kernel oopses/warnings for the week of May 30th 2008

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Date:	Fri, 30 May 2008 15:34:20 -0700
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Hugh Dickins <hugh@...itas.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, Greg KH <greg@...ah.com>,
	Jeff Garzik <jeff@...zik.org>
Subject: Re: Top kernel oopses/warnings for the week of May 30th 2008

Linus Torvalds wrote:
> 
> On Fri, 30 May 2008, Arjan van de Ven wrote:
>> ok for some it did gather this information, and it is
>>
>> kernel BUG at mm/highmem.c:319!
> 
> That's just _odd_. The call chain actually has kmap() in it, and kmap 
> does:
> 
> 	if (!PageHighMem(page))
> 		return page_address(page);
> 	return kmap_high(page);
> 
> so if it's the one at line 319, which says
> 
> 	BUG_ON(!PageHighMem(page));
> 
> then I wonder what happened to that PageHighMem() test of the page in 
> between..
> 
> Ahh.. Not the same "page". It looks like it's in the 
> flush_all_zero_pkmaps() path, and it's clearing some _other_ page in the 
> pkmap table in order to make room for the new one. So the page that causes 
> problems is from here:
> 
> 	 page = pte_page(pkmap_page_table[i]);
> 
> rather than the one we're trying to map.
> 
> Not that it explains the BUG_ON(). We should only insert page table 
> entries into the pkmap_page_table[] array in map_new_virtual(), which in 
> turn is only called from kmap_high(), which in turn means that *those* 
> pages have also gine through the PageHighMem() test.
> 
> So it sounds like we either
>  - have corruption in pkmap_page_table[]
>  - or pte_page() doesn't reverse mk_pte(page) propely, and one or the 
>    other is broken.
> 
> Does anybody know if the fc9 x86-32 kernel is built with PAE enabled? 

versions that do identify themselves as "2.6.25-14.fc9.i686.PAE", and these ones didn't,
(they're all in the "2.6.25-14.fc9.i686" form) so this is a kernel without PAE.
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