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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: "hugh@veritas.com" <hugh@veritas.com>
Cc: Gene Heskett <gene.heskett@gmail.com>,
	David Newall <davidn@davidnewall.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: BUG?: PAGE_FLAGS_CHECK_AT_PREP seems to be cleared too early (Was Re: I just got got another Oops
Date: Mon, 16 Mar 2009 17:03:59 +0900	[thread overview]
Message-ID: <20090316170359.858e7a4e.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <20090316115509.40ea13da.kamezawa.hiroyu@jp.fujitsu.com>

Hi,
I'm sorry if I miss something..

>From this patch
==
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=79f4b7bf393e67bbffec807cc68caaefc72b82ee
==
#define PAGE_FLAGS_CHECK_AT_PREP       ((1 << NR_PAGEFLAGS) - 1)
...
@@ -468,16 +467,16 @@ static inline int free_pages_check(struct page *page)
                (page_count(page) != 0)  |
                (page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
....
+       if (PageReserved(page))
+               return 1;
+       if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
+               page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+       return 0;
 }
==

PAGE_FLAGS_CHECK_AT_PREP is cleared by free_pages_check().

This means PG_head/PG_tail(PG_compound) flags are cleared here and Compound page
will never be freed in sane way.

Regards,
-Kame

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  parent reply	other threads:[~2009-03-16  8:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <200903120133.11583.gene.heskett@gmail.com>
     [not found] ` <49B8C98D.3020309@davidnewall.com>
     [not found]   ` <200903121431.49437.gene.heskett@gmail.com>
2009-03-16  2:55     ` KAMEZAWA Hiroyuki
2009-03-16  3:22       ` KAMEZAWA Hiroyuki
2009-03-16  8:03       ` KAMEZAWA Hiroyuki [this message]
2009-03-16 21:44         ` BUG?: PAGE_FLAGS_CHECK_AT_PREP seems to be cleared too early (Was " Hugh Dickins
2009-03-16 23:44           ` KAMEZAWA Hiroyuki
2009-03-20 15:23           ` Mel Gorman
2009-03-22 14:55             ` Hugh Dickins
2009-03-23 11:27               ` Mel Gorman

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