From: Bob Liu <lliubbo@gmail.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Michel Lespinasse <walken@google.com>,
Sasha Levin <sasha.levin@oracle.com>,
Dave Jones <davej@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
Linux-MM <linux-mm@kvack.org>,
Linux-Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] thp: close race between split and zap huge pages
Date: Thu, 17 Apr 2014 08:28:20 +0800 [thread overview]
Message-ID: <CAA_GA1d1uKtqAxhgzx-pwkymvndmJb4PpMLQZHcetvgf16vBeg@mail.gmail.com> (raw)
In-Reply-To: <20140416084236.GA23247@node.dhcp.inet.fi>
On Wed, Apr 16, 2014 at 4:42 PM, Kirill A. Shutemov
<kirill@shutemov.name> wrote:
> On Wed, Apr 16, 2014 at 07:52:29AM +0800, Bob Liu wrote:
>> > *ptl = pmd_lock(mm, pmd);
>> > - if (pmd_none(*pmd))
>> > + if (!pmd_present(*pmd))
>> > goto unlock;
>>
>> But I didn't get the idea why pmd_none() was removed?
>
> !pmd_present(*pmd) is weaker check then pmd_none(*pmd). I mean if
> pmd_none(*pmd) is true then pmd_present(*pmd) is always false.
Oh, yes. That's right.
BTW, it looks like this bug was introduced by the same reason.
https://lkml.org/lkml/2014/4/16/403
--
Regards,
--Bob
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next prev parent reply other threads:[~2014-04-17 0:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-15 21:48 Kirill A. Shutemov
2014-04-15 23:52 ` Bob Liu
2014-04-16 8:42 ` Kirill A. Shutemov
2014-04-17 0:28 ` Bob Liu [this message]
2014-04-17 20:16 ` Andrea Arcangeli
-- strict thread matches above, loose matches on Subject: below --
2014-04-15 21:48 Kirill A. Shutemov
2014-04-16 14:46 ` Sasha Levin
2014-04-16 20:19 ` Andrew Morton
2014-04-18 20:56 ` Kirill A. Shutemov
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