linux-kernel - Re: [PATCHv4 39/39] thp: map file-backed huge pages on fault

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Date:	Thu, 23 May 2013 14:48:29 +0300 (EEST)
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Hillf Danton <dhillf@...il.com>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Hugh Dickins <hughd@...gle.com>,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <matthew.r.wilcox@...el.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Dave Hansen <dave@...1.net>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 39/39] thp: map file-backed huge pages on fault

Hillf Danton wrote:
> On Sun, May 12, 2013 at 9:23 AM, Kirill A. Shutemov
> <kirill.shutemov@...ux.intel.com> wrote:
> > From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> >
> > Look like all pieces are in place, we can map file-backed huge-pages
> > now.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> > ---
> >  include/linux/huge_mm.h |    4 +++-
> >  mm/memory.c             |    5 ++++-
> >  2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> > index f4d6626..903f097 100644
> > --- a/include/linux/huge_mm.h
> > +++ b/include/linux/huge_mm.h
> > @@ -78,7 +78,9 @@ extern bool is_vma_temporary_stack(struct vm_area_struct *vma);
> >            (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) &&                   \
> >            ((__vma)->vm_flags & VM_HUGEPAGE))) &&                       \
> >          !((__vma)->vm_flags & VM_NOHUGEPAGE) &&                        \
> > -        !is_vma_temporary_stack(__vma))
> > +        !is_vma_temporary_stack(__vma) &&                              \
> > +        (!(__vma)->vm_ops ||                                           \
> > +                 mapping_can_have_hugepages((__vma)->vm_file->f_mapping)))
> 
> Redefine, why?
> 
> >  #define transparent_hugepage_defrag(__vma)                             \
> >         ((transparent_hugepage_flags &                                  \
> >           (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) ||                     \
> > diff --git a/mm/memory.c b/mm/memory.c
> > index ebff552..7fe9752 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -3939,10 +3939,13 @@ retry:
> >         if (!pmd)
> >                 return VM_FAULT_OOM;
> >         if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
> > -               int ret = 0;
> > +               int ret;
> >                 if (!vma->vm_ops)
> >                         ret = do_huge_pmd_anonymous_page(mm, vma, address,
> >                                         pmd, flags);
> 
> Ah vma->vm_ops is checked here, so
> 		else if (mapping_can_have_hugepages())

Okay, it's cleaner.

-- 
 Kirill A. Shutemov
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