From: Zhang Yanfei <zhangyanfei.linux@aliyun.com>
To: Vlastimil Babka <vbabka@suse.cz>,
Andrea Arcangeli <aarcange@redhat.com>,
Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
kirill@shutemov.name, mhocko@suse.cz, mgorman@suse.de,
rientjes@google.com, sasha.levin@oracle.com, hughd@google.com,
hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
riel@redhat.com
Subject: Re: [PATCH] mm: incorporate read-only pages into transparent huge pages
Date: Sun, 25 Jan 2015 22:42:56 +0800 [thread overview]
Message-ID: <54C500F0.3070903@aliyun.com> (raw)
In-Reply-To: <54C4B680.3010304@suse.cz>
Hello
a?? 2015/1/25 17:25, Vlastimil Babka a??e??:
> On 23.1.2015 20:18, Andrea Arcangeli wrote:
>>> >+ if (!pte_write(pteval)) {
>>> >+ if (++ro > khugepaged_max_ptes_none)
>>> >+ goto out_unmap;
>>> >+ }
>> It's true this is maxed out at 511, so there must be at least one
>> writable and not none pte (as results of the two "ro" and "none"
>> counters checks).
>
> Hm, but if we consider ro and pte_none separately, both can be lower
> than 512, but the sum of the two can be 512, so we can actually be in
> read-only VMA?
Yes, I also think so.
So is it necessary to add a at-least-one-writable-pte check just like the existing
at-least-one-page-referenced check?
Thanks.
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prev parent reply other threads:[~2015-01-25 14:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-23 7:47 [PATCH] mm: incorporate read-only pages into transparent huge pages Ebru Akagunduz
2015-01-23 11:37 ` Kirill A. Shutemov
2015-01-23 14:57 ` Rik van Riel
2015-01-23 15:58 ` Kirill A. Shutemov
2015-01-23 16:12 ` Vlastimil Babka
2015-01-23 16:15 ` Rik van Riel
2015-01-23 19:04 ` Rik van Riel
2015-01-23 19:18 ` Andrea Arcangeli
2015-01-25 9:25 ` Vlastimil Babka
2015-01-25 14:42 ` Zhang Yanfei [this message]
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