From: Michal Hocko <mhocko@suse.cz>
To: Hillf Danton <dhillf@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
Hugh Dickins <hughd@google.com>, Linux-MM <linux-mm@kvack.org>,
David Gibson <david@gibson.dropbear.id.au>,
Ken Chen <kenchen@google.com>,
Cong Wang <xiyou.wangcong@gmail.com>
Subject: Re: [PATCH -mm] mm: hugetlbfs: Correctly populate shared pmd
Date: Fri, 3 Aug 2012 16:37:48 +0200 [thread overview]
Message-ID: <20120803143748.GD8434@dhcp22.suse.cz> (raw)
In-Reply-To: <CAJd=RBDnzbLpqsVkishsZmB518mCu0Go0o2ZOGdHj62qRfLnAg@mail.gmail.com>
On Fri 03-08-12 22:16:52, Hillf Danton wrote:
> On Thu, Aug 2, 2012 at 10:16 PM, Michal Hocko <mhocko@suse.cz> wrote:
> > This patch addresses the issue by moving pmd_alloc into huge_pmd_share
> > which guarantees that the shared pud is populated in the same
> > critical section as pmd.
>
> Is i_mmap_mutex for guarding new pmd allocation?
It doesn't guard the pmd allocation itself it just makes sure that pud
population and pmd_allocation are done atomicaly wrt. other processes to
share the same pmd because sharing is synchronized by i_mmap_mutex.
> Is regression introduced if sharing is unavailable?
No. The bug is about the sharing as the changelog describes.
--
Michal Hocko
SUSE Labs
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prev parent reply other threads:[~2012-08-03 14:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-02 14:16 [PATCH -mm] mm: hugetlbfs: Correctly populate shared pmd Michal Hocko
2012-08-02 14:40 ` Rik van Riel
2012-08-03 14:16 ` Hillf Danton
2012-08-03 14:37 ` Michal Hocko [this message]
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