linux-kernel - Re: Oops in 3.7-rc8 isolate_free_pages

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Message-ID: <20121206213909.GA625@polaris.bitmath.org>
Date:	Thu, 6 Dec 2012 22:39:09 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Mel Gorman <mgorman@...e.de>, Jan Kara <jack@...e.cz>,
	linux-mm <linux-mm@...ck.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Oops in 3.7-rc8 isolate_free_pages_block()

> There is also a
> 
>     low_pfn += pageblock_nr_pages;
>     low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
> 
> that looks suspicious for similar reasons. Maybe
> 
>     low_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages) - 1;
> 
> instead? Although that *can* result in the same low_pfn in the end, so
> maybe that one was correct after all? I just did some grepping, no
> actual semantic analysis...

Here is a totally obscure version:

	low_pfn |= pageblock_nr_pages - 1;

It simply moves to the very end of the block, which seems to be what
was intended.

Henrik
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