From: David Rientjes <rientjes@google.com>
To: Johannes Weiner <jweiner@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm@kvack.org
Subject: Re: [patch v2] thp, memcg: split hugepage for memcg oom on cow
Date: Wed, 25 Apr 2012 14:01:29 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1204251359440.29822@chino.kir.corp.google.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1204231612060.17030@chino.kir.corp.google.com>
On Mon, 23 Apr 2012, David Rientjes wrote:
> > Can you instead put a __split_huge_page_pmd(mm, pmd) here? It has to
> > redo the get-page-ref-through-pagetable dance, but it's more robust
> > and obvious than splitting the COW page before returning OOM in the
> > thp wp handler.
> >
>
> I agree it's more robust if do_huge_pmd_wp_page() were modified later and
> mistakenly returned VM_FAULT_OOM without the page being split, but
> __split_huge_page_pmd() has the drawback of also requiring to retake
> mm->page_table_lock to test whether orig_pmd is still legitimate so it
> will be slower. Do you feel strongly about the way it's currently written
> which will be faster at runtime?
>
Andrew, please merge this patch. I'd rather not unnecessarily take
another reference on the cow page and unnecessarily take
mm->page_table_lock in the page fault handler so the code is cleaner.
It's faster this way.
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next prev parent reply other threads:[~2012-04-25 21:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-04 1:56 [patch] thp, memcg: split hugepage for memcg oom on cow David Rientjes
2012-04-09 9:10 ` KAMEZAWA Hiroyuki
2012-04-10 0:23 ` David Rientjes
2012-04-10 0:43 ` KAMEZAWA Hiroyuki
2012-04-10 0:49 ` KAMEZAWA Hiroyuki
2012-04-10 5:41 ` David Rientjes
2012-04-10 5:42 ` [patch v2] " David Rientjes
2012-04-10 5:59 ` KAMEZAWA Hiroyuki
2012-04-11 14:20 ` Johannes Weiner
2012-04-23 23:15 ` David Rientjes
2012-04-25 21:01 ` David Rientjes [this message]
2012-04-26 9:06 ` Johannes Weiner
2012-04-26 21:05 ` David Rientjes
2012-04-27 0:15 ` Johannes Weiner
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