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Date: Mon, 28 Jul 2014 16:02:31 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
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To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
cc: Andrew Morton <akpm@linux-foundation.org>, Hugh Dickins <hughd@google.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH 2/3] mm/hugetlb: take refcount under page table lock in
 follow_huge_pmd()
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On Mon, 28 Jul 2014, Naoya Horiguchi wrote:

> We have a race condition between move_pages() and freeing hugepages,
> where move_pages() calls follow_page(FOLL_GET) for hugepages internally
> and tries to get its refcount without preventing concurrent freeing.
> This race crashes the kernel, so this patch fixes it by moving FOLL_GET
> code for hugepages into follow_huge_pmd() with taking the page table lock.
> 

What about CONFIG_ARCH_WANT_GENERAL_HUGETLB=n configs?