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Date: Wed, 22 Apr 2009 19:41:58 +0900
Message-ID: <2f11576a0904220341s839b3e9m70d49dc1af27e89@mail.gmail.com>
Subject: Re: [PATCH 20/25] Do not check for compound pages during the page
	allocator sanity checks
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
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Sender: owner-linux-mm@kvack.org
To: Mel Gorman <mel@csn.ul.ie>
Cc: Linux Memory Management List <linux-mm@kvack.org>, Christoph Lameter <cl@linux-foundation.org>, Nick Piggin <npiggin@suse.de>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Lin Ming <ming.m.lin@intel.com>, Zhang Yanmin <yanmin_zhang@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, Pekka Enberg <penberg@cs.helsinki.fi>, Andrew Morton <akpm@linux-foundation.org>
List-ID: <linux-mm.kvack.org>

>> inserting VM_BUG_ON(PageTail(page)) is better?
>>
>
> We already go one further with
>
> #define PAGE_FLAGS_CHECK_AT_PREP =A0 =A0 =A0 =A0((1 << NR_PAGEFLAGS) - 1)
>
> ...
>
> if (.... | (page->flags & PAGE_FLAGS_CHECK_AT_PREP))
> =A0 =A0 =A0 =A0bad_page(page);
>
> PG_tail is in PAGE_FLAGS_CHECK_AT_PREP so we're already checking for it
> and calling bad_page() if set.

ok, good.

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