Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common path

From	"Hillf Danton" <hillf.zj@alibaba-inc.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common path
Date	2016-11-10 10:40 +0100
Message-ID	<sBTZU-3Mb-5@gated-at.bofh.it> (permalink)
References	<sB1Ga-1xZ-7@gated-at.bofh.it> <sB1Zw-1Es-23@gated-at.bofh.it> <sBTQe-3Ic-19@gated-at.bofh.it> <sBTQe-3Ic-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Thursday, November 10, 2016 5:22 PM Naoya Horiguchi wrote:
> On Thu, Nov 10, 2016 at 05:08:07PM +0800, Hillf Danton wrote:
> > On Tuesday, November 08, 2016 7:32 AM Naoya Horiguchi wrote:
> > >
> > > @@ -1013,6 +1027,9 @@ int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t orig_pmd)
> > >  	if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
> > >  		goto out_unlock;
> > >
> > > +	if (unlikely(!pmd_present(orig_pmd)))
> > > +		goto out_unlock;
> > > +
> >
> > Can we encounter a migration entry after acquiring ptl ?
> 
> I think we can. thp migration code releases ptl after converting pmd into
> migration entry, so other code can see it even within ptl.
> 
But we have a pmd_same check there, you see.

Thread

[PATCH v2 00/12] mm: page migration enhancement for thp Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-08 00:40 +0100
  [PATCH v2 02/12] mm: mempolicy: add queue_pages_node_check() Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-08 00:50 +0100
  [PATCH v2 07/12] mm: thp: check pmd migration entry in common path Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-08 01:00 +0100
    Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common  path kbuild test robot <lkp@intel.com> - 2016-11-08 01:30 +0100
      Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common  path Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-08 02:30 +0100
    Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common  path Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-10 09:40 +0100
      Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common  path Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-10 10:20 +0100
    Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common  path Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-10 10:30 +0100
      Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common  path Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-10 10:40 +0100
      Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common path "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-11-10 10:40 +0100
    Re: [PATCH v2 07/12] mm: thp: check pmd migration entry in common path "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-11-10 10:30 +0100
  [PATCH v2 06/12] mm: thp: enable thp migration in generic path Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-08 01:40 +0100
  Re: [PATCH v2 00/12] mm: page migration enhancement for thp Balbir Singh <bsingharora@gmail.com> - 2016-11-09 03:40 +0100
    Re: [PATCH v2 00/12] mm: page migration enhancement for thp Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-09 06:10 +0100
      Re: [PATCH v2 00/12] mm: page migration enhancement for thp Balbir Singh <bsingharora@gmail.com> - 2016-11-09 22:30 +0100
  Re: [PATCH v2 00/12] mm: page migration enhancement for thp Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-09 11:40 +0100
    Re: [PATCH v2 00/12] mm: page migration enhancement for thp Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-11-10 01:00 +0100
      Re: [PATCH v2 00/12] mm: page migration enhancement for thp Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2016-11-11 04:50 +0100

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