From: Nick Piggin <npiggin@suse.de>
To: Andi Kleen <andi@firstfloor.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] HWPOISON: remove the unsafe __set_page_locked()
Date: Sat, 26 Sep 2009 21:12:01 +0200 [thread overview]
Message-ID: <20090926191201.GC14368@wotan.suse.de> (raw)
In-Reply-To: <20090926150555.GM30185@one.firstfloor.org>
On Sat, Sep 26, 2009 at 05:05:55PM +0200, Andi Kleen wrote:
> > However we may well end up to accept the fact that "we just cannot do
> > hwpoison 100% correct", and settle with a simple and 99% correct code.
>
> I would prefer to avoid any oopses, but if they are unlikely enough
> and too hard to fix that's bearable. The race window here is certainly rather
> small.
Well, several places non-atomically modify page flags, including
within preempt-enabled regions... It's nasty to introduce these
oopses in the hwposion code! I'm ashamed I didn't pick up on this
problem seeing as I introduced several of them.
> On the other hand if you cannot detect a difference in benchmarks I see
> no reason not to add the additional steps, as long as the code isn't
> complicated or ugly. These changes are neither.
The patch to add atomics back into the fastpaths? I don't think that's
acceptable at all. A config option doesn't go far enough either because
distros will have to turn it on.
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next prev parent reply other threads:[~2009-09-26 19:12 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-26 3:15 [RFC][PATCH] HWPOISON: remove the unsafe __set_page_locked() Wu Fengguang
2009-09-26 3:49 ` Andi Kleen
2009-09-26 10:52 ` Wu Fengguang
2009-09-26 11:31 ` Wu Fengguang
2009-09-27 10:47 ` Wu Fengguang
2009-09-27 19:20 ` Nick Piggin
2009-09-28 8:44 ` Wu Fengguang
2009-09-29 5:16 ` Wu Fengguang
2009-10-01 2:02 ` Nick Piggin
2009-10-02 10:54 ` Wu Fengguang
2009-09-26 11:09 ` Hugh Dickins
2009-09-26 11:48 ` Wu Fengguang
2009-09-26 11:58 ` Hugh Dickins
2009-09-26 15:05 ` Andi Kleen
2009-09-26 19:12 ` Nick Piggin [this message]
2009-09-26 19:14 ` Nick Piggin
2009-09-26 19:06 ` Nick Piggin
2009-09-26 21:32 ` Andi Kleen
2009-09-27 16:26 ` Hugh Dickins
2009-09-27 19:22 ` Nick Piggin
2009-09-27 21:57 ` Hugh Dickins
2009-09-27 23:01 ` Nick Piggin
2009-09-28 1:19 ` Andi Kleen
2009-09-28 1:52 ` Wu Fengguang
2009-09-28 2:57 ` Nick Piggin
2009-09-28 4:11 ` Andi Kleen
2009-09-28 4:29 ` Nick Piggin
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