From: Rik van Riel <riel@redhat.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>, Linux-MM <linux-mm@kvack.org>,
Hugh Dickins <hughd@google.com>,
David Gibson <david@gibson.dropbear.id.au>,
Ken Chen <kenchen@google.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -alternative] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend)
Date: Thu, 26 Jul 2012 14:31:50 -0400 [thread overview]
Message-ID: <50118D16.4050603@redhat.com> (raw)
In-Reply-To: <20120720143635.GE12434@tiehlicka.suse.cz>
On 07/20/2012 10:36 AM, Michal Hocko wrote:
> --- a/arch/x86/mm/hugetlbpage.c
> +++ b/arch/x86/mm/hugetlbpage.c
> @@ -81,7 +81,12 @@ static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
> if (saddr) {
> spte = huge_pte_offset(svma->vm_mm, saddr);
> if (spte) {
> - get_page(virt_to_page(spte));
> + struct page *spte_page = virt_to_page(spte);
> + if (!is_hugetlb_pmd_page_valid(spte_page)) {
What prevents somebody else from marking the hugetlb
pmd invalid, between here...
> + spte = NULL;
> + continue;
> + }
... and here?
> + get_page(spte_page);
> break;
> }
I think need to take the refcount before checking whether
the hugetlb pmd is still valid.
Also, disregard my previous email in this thread, I just
read Mel's detailed explanation and wrapped my brain
around the bug :)
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>, Linux-MM <linux-mm@kvack.org>,
Hugh Dickins <hughd@google.com>,
David Gibson <david@gibson.dropbear.id.au>,
Ken Chen <kenchen@google.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -alternative] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend)
Date: Thu, 26 Jul 2012 14:31:50 -0400 [thread overview]
Message-ID: <50118D16.4050603@redhat.com> (raw)
In-Reply-To: <20120720143635.GE12434@tiehlicka.suse.cz>
On 07/20/2012 10:36 AM, Michal Hocko wrote:
> --- a/arch/x86/mm/hugetlbpage.c
> +++ b/arch/x86/mm/hugetlbpage.c
> @@ -81,7 +81,12 @@ static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
> if (saddr) {
> spte = huge_pte_offset(svma->vm_mm, saddr);
> if (spte) {
> - get_page(virt_to_page(spte));
> + struct page *spte_page = virt_to_page(spte);
> + if (!is_hugetlb_pmd_page_valid(spte_page)) {
What prevents somebody else from marking the hugetlb
pmd invalid, between here...
> + spte = NULL;
> + continue;
> + }
... and here?
> + get_page(spte_page);
> break;
> }
I think need to take the refcount before checking whether
the hugetlb pmd is still valid.
Also, disregard my previous email in this thread, I just
read Mel's detailed explanation and wrapped my brain
around the bug :)
next prev parent reply other threads:[~2012-07-26 18:33 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 13:49 [PATCH] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables v2 Mel Gorman
2012-07-20 13:49 ` Mel Gorman
2012-07-20 14:11 ` [PATCH] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend) Mel Gorman
2012-07-20 14:11 ` Mel Gorman
2012-07-20 14:29 ` Michal Hocko
2012-07-20 14:29 ` Michal Hocko
2012-07-20 14:37 ` Mel Gorman
2012-07-20 14:37 ` Mel Gorman
2012-07-20 14:40 ` Michal Hocko
2012-07-20 14:40 ` Michal Hocko
2012-07-20 14:36 ` [PATCH -alternative] " Michal Hocko
2012-07-20 14:36 ` Michal Hocko
2012-07-20 14:51 ` Mel Gorman
2012-07-20 14:51 ` Mel Gorman
2012-07-23 4:04 ` Hugh Dickins
2012-07-23 4:04 ` Hugh Dickins
2012-07-23 11:40 ` Mel Gorman
2012-07-23 11:40 ` Mel Gorman
2012-07-24 1:08 ` Hugh Dickins
2012-07-24 1:08 ` Hugh Dickins
2012-07-24 8:32 ` Michal Hocko
2012-07-24 8:32 ` Michal Hocko
2012-07-24 9:34 ` Mel Gorman
2012-07-24 9:34 ` Mel Gorman
2012-07-24 10:04 ` Michal Hocko
2012-07-24 10:04 ` Michal Hocko
2012-07-24 19:23 ` Hugh Dickins
2012-07-24 19:23 ` Hugh Dickins
2012-07-25 8:36 ` Mel Gorman
2012-07-25 8:36 ` Mel Gorman
2012-07-26 17:42 ` Rik van Riel
2012-07-26 17:42 ` Rik van Riel
2012-07-26 18:04 ` Larry Woodman
2012-07-26 18:04 ` Larry Woodman
2012-07-27 8:42 ` Mel Gorman
2012-07-27 8:42 ` Mel Gorman
2012-07-26 18:37 ` Rik van Riel
2012-07-26 18:37 ` Rik van Riel
2012-07-26 21:03 ` Larry Woodman
2012-07-26 21:03 ` Larry Woodman
2012-07-27 3:48 ` Larry Woodman
2012-07-27 3:48 ` Larry Woodman
2012-07-27 10:10 ` Larry Woodman
2012-07-27 10:10 ` Larry Woodman
2012-07-27 10:23 ` Mel Gorman
2012-07-27 10:23 ` Mel Gorman
2012-07-27 10:36 ` Larry Woodman
2012-07-27 10:36 ` Larry Woodman
2012-07-30 19:11 ` Larry Woodman
2012-07-30 19:11 ` Larry Woodman
2012-07-31 12:16 ` Hillf Danton
2012-07-31 12:16 ` Hillf Danton
2012-07-31 12:46 ` Mel Gorman
2012-07-31 12:46 ` Mel Gorman
2012-07-31 13:07 ` Larry Woodman
2012-07-31 13:07 ` Larry Woodman
2012-07-31 13:29 ` Mel Gorman
2012-07-31 13:29 ` Mel Gorman
2012-07-31 13:21 ` Michal Hocko
2012-07-31 13:21 ` Michal Hocko
2012-07-31 17:49 ` Larry Woodman
2012-07-31 17:49 ` Larry Woodman
2012-07-31 20:06 ` Michal Hocko
2012-07-31 20:06 ` Michal Hocko
2012-07-31 20:57 ` Larry Woodman
2012-07-31 20:57 ` Larry Woodman
2012-08-01 2:45 ` Larry Woodman
2012-08-01 2:45 ` Larry Woodman
2012-08-01 8:20 ` Michal Hocko
2012-08-01 8:20 ` Michal Hocko
2012-08-01 12:32 ` Michal Hocko
2012-08-01 12:32 ` Michal Hocko
2012-08-01 15:06 ` Larry Woodman
2012-08-01 15:06 ` Larry Woodman
2012-08-02 7:19 ` Michal Hocko
2012-08-02 7:19 ` Michal Hocko
2012-08-02 7:37 ` Mel Gorman
2012-08-02 7:37 ` Mel Gorman
2012-08-02 12:36 ` Michal Hocko
2012-08-02 12:36 ` Michal Hocko
2012-08-02 13:33 ` Mel Gorman
2012-08-02 13:33 ` Mel Gorman
2012-08-02 13:53 ` Michal Hocko
2012-08-02 13:53 ` Michal Hocko
2012-07-31 18:03 ` Rik van Riel
2012-07-31 18:03 ` Rik van Riel
2012-07-26 18:31 ` Rik van Riel [this message]
2012-07-26 18:31 ` Rik van Riel
2012-07-27 9:02 ` Michal Hocko
2012-07-27 9:02 ` Michal Hocko
2012-07-26 16:01 ` [PATCH] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables v2 Larry Woodman
2012-07-26 16:01 ` Larry Woodman
2012-07-27 8:47 ` Mel Gorman
2012-07-27 8:47 ` Mel Gorman
2012-07-26 21:00 ` Rik van Riel
2012-07-26 21:00 ` Rik van Riel
2012-07-26 21:54 ` Hugh Dickins
2012-07-26 21:54 ` Hugh Dickins
2012-07-27 8:52 ` Mel Gorman
2012-07-27 8:52 ` Mel Gorman
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