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From: Andrea Arcangeli <aarcange@redhat.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"hannes@cmpxchg.org" <hannes@cmpxchg.org>
Subject: Re: [mmotm] BUG: Bad page state in process khugepaged ?
Date: Wed, 9 Feb 2011 21:07:28 +0100	[thread overview]
Message-ID: <20110209200728.GQ3347@random.random> (raw)
In-Reply-To: <20110209155246.69a7f3a1.kamezawa.hiroyu@jp.fujitsu.com>

On Wed, Feb 09, 2011 at 03:52:46PM +0900, KAMEZAWA Hiroyuki wrote:
> On Wed, 9 Feb 2011 15:50:01 +0900
> Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> 
> > > 
> > > In hex, pc->flags was 7A00000000004 and this means PCG_USED bit is set.
> > > This implies page_remove_rmap() may not be called but ->mapping is NULL. Hmm?
> > > (7A is encoding of section number.)
> > > 
> > Sigh.. it seems another freed-but-not-uncharged problem..
> > 
> 
> Ah, ok, this is maybe caused by this. I'm sorry that I missed this.
> ==
> static inline int free_pages_check(struct page *page)
> {
>         if (unlikely(page_mapcount(page) |
>                 (page->mapping != NULL)  |
>                 (atomic_read(&page->_count) != 0) |
>                 (page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
>                 (mem_cgroup_bad_page_check(page)))) {    <==========(*)
>                 bad_page(page);
>                 return 1;
> ==
> 
> Then, ok, this is a memcgroup and hugepage issue.
> 
> I'll look into.

Yes, the rest of the info on the page looked ok and shouldn't have
triggered a bad_page call. Thanks so much for looking into it.

Andrea

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  reply	other threads:[~2011-02-09 20:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-09  6:10 [mmotm] BUG: Bad page state in process khugepaged ? KAMEZAWA Hiroyuki
2011-02-09  6:40 ` KAMEZAWA Hiroyuki
2011-02-09  6:50 ` Daisuke Nishimura
2011-02-09  6:52   ` KAMEZAWA Hiroyuki
2011-02-09 20:07     ` Andrea Arcangeli [this message]
2011-02-11  7:02       ` Hugh Dickins
2011-02-11 10:49         ` Andrea Arcangeli
2011-02-11 19:58           ` Hugh Dickins
2011-02-11 20:24             ` Andrea Arcangeli
2011-02-14 22:24           ` Johannes Weiner
2011-02-09  7:23 ` [PATCH][BUGFIX] memcg: fix leak of accounting at failure path of hugepage collapsing KAMEZAWA Hiroyuki
2011-02-09  7:51   ` Daisuke Nishimura
2011-02-09  9:51   ` Johannes Weiner
2011-02-10  2:49   ` Minchan Kim

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