From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "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>,
Andrea Arcangeli <aarcange@redhat.com>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
"nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>
Subject: Re: [mmotm] BUG: Bad page state in process khugepaged ?
Date: Wed, 9 Feb 2011 15:40:17 +0900 [thread overview]
Message-ID: <20110209154017.f6489f4e.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <20110209151036.f24a36a6.kamezawa.hiroyu@jp.fujitsu.com>
On Wed, 9 Feb 2011 15:10:36 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> 2nd log, "kernel BUG at include/linux/mm.h:420!" is This one.
> ==
> static inline void __ClearPageBuddy(struct page *page)
> {
> VM_BUG_ON(!PageBuddy(page));
> atomic_set(&page->_mapcount, -1);
> }
> ==
> But this is just a tail of bad_page().
> ==
> static void bad_page(struct page *page)
> {
> static unsigned long resume;
> static unsigned long nr_shown;
> static unsigned long nr_unshown;
> ...
> dump_stack();
> out:
> /* Leave bad fields for debug, except PageBuddy could make trouble */
> __ClearPageBuddy(page);
> add_taint(TAINT_BAD_PAGE);
> }
> ==
> So, what important is bad_page().
>
> BAD page says
> ==
> BUG: Bad page state in process khugepaged pfn:1e9800
> page:ffffea0006b14000 count:0 mapcount:0 mapping: (null) index:0x2800
> page flags: 0x40000000004000(head)
> pc:ffff880214a30000 pc->flags:2146246697418756 pc->mem_cgroup:ffffc9000177a000
> ==
>
> Maybe page_mapcount(page) was > 0. and ->mapping was NULL.
Sorry please ignore above. bad_page() used page_mapcount().
Regards,
-Kame
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next prev parent reply other threads:[~2011-02-09 6:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-09 6:10 KAMEZAWA Hiroyuki
2011-02-09 6:40 ` KAMEZAWA Hiroyuki [this message]
2011-02-09 6:50 ` Daisuke Nishimura
2011-02-09 6:52 ` KAMEZAWA Hiroyuki
2011-02-09 20:07 ` Andrea Arcangeli
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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