From: Peter Zijlstra <peterz@infradead.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linux-mm@kvack.org, Will Deacon <will.deacon@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] numa, mm: drop redundant check in do_huge_pmd_numa_page()
Date: Fri, 26 Oct 2012 16:07:44 +0200 [thread overview]
Message-ID: <1351260464.16863.80.camel@twins> (raw)
In-Reply-To: <20121026135750.GA16598@otc-wbsnb-06>
On Fri, 2012-10-26 at 16:57 +0300, Kirill A. Shutemov wrote:
> > > Yes, this code will catch it:
> > >
> > > /* if an huge pmd materialized from under us just retry later */
> > > if (unlikely(pmd_trans_huge(*pmd)))
> > > return 0;
> > >
> > > If the pmd is under splitting it's still a pmd_trans_huge().
> >
> > OK, so then we simply keep taking the same fault until the split is
> > complete? Wouldn't it be better to wait for it instead of spin on
> > faults?
>
> IIUC, on next fault we will wait split the page in fallow_page().
What follow_page()?, a regular hardware page-fault will not call
follow_page() afaict, we do a down_read(), find_vma() and call
handle_mm_fault() -- with a lot of error and corner case checking in
between.
next prev parent reply other threads:[~2012-10-26 14:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-26 12:54 [PATCH 1/2] numa, mm: drop redundant check in do_huge_pmd_numa_page() Kirill A. Shutemov
2012-10-26 12:54 ` [PATCH 2/2] numa, mm: consolidate error path " Kirill A. Shutemov
2012-10-26 13:10 ` Peter Zijlstra
2012-10-26 13:08 ` [PATCH 1/2] numa, mm: drop redundant check " Peter Zijlstra
2012-10-26 13:41 ` Kirill A. Shutemov
2012-10-26 13:43 ` Peter Zijlstra
2012-10-26 13:57 ` Kirill A. Shutemov
2012-10-26 14:07 ` Peter Zijlstra [this message]
2012-10-26 14:34 ` Kirill A. Shutemov
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