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Message-Id: <1423757918-197669-9-git-send-email-kirill.shutemov@linux.intel.com>
Date: Thu, 12 Feb 2015 18:18:22 +0200
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Hugh Dickins <hughd@...gle.com>
Cc: Dave Hansen <dave.hansen@...el.com>, Mel Gorman <mgorman@...e.de>,
Rik van Riel <riel@...hat.com>,
Vlastimil Babka <vbabka@...e.cz>,
Christoph Lameter <cl@...two.org>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Steve Capper <steve.capper@...aro.org>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...e.cz>,
Jerome Marchand <jmarchan@...hat.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv3 08/24] mm: adjust FOLL_SPLIT for new refcounting
We prepare kernel to allow transhuge pages to be mapped with ptes too.
We need to handle FOLL_SPLIT in follow_page_pte().
Also we use split_huge_page() directly instead of split_huge_page_pmd().
split_huge_page_pmd() will gone.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
mm/gup.c | 65 ++++++++++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 45 insertions(+), 20 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index a6e24e246f86..022d7a91de03 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -79,6 +79,20 @@ retry:
page = pte_page(pte);
}
+ if (flags & FOLL_SPLIT && PageTransCompound(page)) {
+ int ret;
+ page = compound_head(page);
+ get_page(page);
+ pte_unmap_unlock(ptep, ptl);
+ lock_page(page);
+ ret = split_huge_page(page);
+ unlock_page(page);
+ put_page(page);
+ if (ret)
+ return ERR_PTR(ret);
+ goto retry;
+ }
+
if (flags & FOLL_GET)
get_page_foll(page);
if (flags & FOLL_TOUCH) {
@@ -186,27 +200,38 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
}
if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
return no_page_table(vma, flags);
- if (pmd_trans_huge(*pmd)) {
- if (flags & FOLL_SPLIT) {
- split_huge_page_pmd(vma, address, pmd);
- return follow_page_pte(vma, address, pmd, flags);
- }
- ptl = pmd_lock(mm, pmd);
- if (likely(pmd_trans_huge(*pmd))) {
- if (unlikely(pmd_trans_splitting(*pmd))) {
- spin_unlock(ptl);
- wait_split_huge_page(vma->anon_vma, pmd);
- } else {
- page = follow_trans_huge_pmd(vma, address,
- pmd, flags);
- spin_unlock(ptl);
- *page_mask = HPAGE_PMD_NR - 1;
- return page;
- }
- } else
- spin_unlock(ptl);
+ if (likely(!pmd_trans_huge(*pmd)))
+ return follow_page_pte(vma, address, pmd, flags);
+
+ ptl = pmd_lock(mm, pmd);
+ if (unlikely(!pmd_trans_huge(*pmd))) {
+ spin_unlock(ptl);
+ return follow_page_pte(vma, address, pmd, flags);
}
- return follow_page_pte(vma, address, pmd, flags);
+
+ if (unlikely(pmd_trans_splitting(*pmd))) {
+ spin_unlock(ptl);
+ wait_split_huge_page(vma->anon_vma, pmd);
+ return follow_page_pte(vma, address, pmd, flags);
+ }
+
+ if (flags & FOLL_SPLIT) {
+ int ret;
+ page = pmd_page(*pmd);
+ get_page(page);
+ spin_unlock(ptl);
+ lock_page(page);
+ ret = split_huge_page(page);
+ unlock_page(page);
+ put_page(page);
+ return ret ? ERR_PTR(ret) :
+ follow_page_pte(vma, address, pmd, flags);
+ }
+
+ page = follow_trans_huge_pmd(vma, address, pmd, flags);
+ spin_unlock(ptl);
+ *page_mask = HPAGE_PMD_NR - 1;
+ return page;
}
static int get_gate_page(struct mm_struct *mm, unsigned long address,
--
2.1.4
--
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