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From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	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>
Subject: Re: [mmotm] BUG: Bad page state in process khugepaged ?
Date: Mon, 14 Feb 2011 23:24:21 +0100	[thread overview]
Message-ID: <20110214222421.GZ27110@cmpxchg.org> (raw)
In-Reply-To: <20110211104906.GE3347@random.random>

On Fri, Feb 11, 2011 at 11:49:06AM +0100, Andrea Arcangeli wrote:
> On Thu, Feb 10, 2011 at 11:02:50PM -0800, Hugh Dickins wrote:
> > There is a separate little issue here, Andrea.
> > 
> > Although we went to some trouble for bad_page() to take the page out
> > of circulation yet let the system continue, your VM_BUG_ON(!PageBuddy)
> > inside __ClearPageBuddy(page), from two callsites in bad_page(), is
> > turning it into a fatal error when CONFIG_DEBUG_VM.
> 
> I see what you mean. Of course it is only a problem after bad_page
> already triggered.... but then it trigger an BUG_ON instead of only a
> bad_page.
> 
> > You could that only MM developers switch CONFIG_DEBUG_VM=y, and they
> > would like bad_page() to be fatal; maybe, but if so we should do that
> > as an intentional patch, rather than as an unexpected side-effect ;)
> 
> Fedora kernels are built with CONFIG_DEBUG_VM, all my kernels runs
> with CONFIG_DEBUG_VM too, so we want it to be as "production" as
> possible, and we don't want DEBUG_VM to decrease any reliability (only
> to increase it of course).

Are you sure?

$ grep DEBUG_VM /boot/config-*
/boot/config-2.6.35.10-74.fc14.x86_64:# CONFIG_DEBUG_VM is not set
/boot/config-2.6.35.6-45.fc14.x86_64:# CONFIG_DEBUG_VM is not set

Only the one from the kernel-debug package has it set on this F14.

	Hannes

  parent reply	other threads:[~2011-02-14 22:24 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
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 [this message]
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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