LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
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






  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110209154017.f6489f4e.kamezawa.hiroyu@jp.fujitsu.com \
    --to=kamezawa.hiroyu@jp.fujitsu.com \
    --cc=aarcange@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=nishimura@mxp.nes.nec.co.jp \
    --subject='Re: [mmotm] BUG: Bad page state in process khugepaged ?' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).