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Date: Wed, 3 Feb 2016 18:14:17 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>
Cc: Hugh Dickins <hughd@...gle.com>,
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>,
Sasha Levin <sasha.levin@...cle.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH 2/4] rmap: extend try_to_unmap() to be usable by split_huge_page()
The patch add support for two ttu_flags:
- TTU_SPLIT_HUGE_PMD would split PMD if it's there, before trying to
unmap page;
- TTU_RMAP_LOCKED indicates that caller holds relevant rmap lock;
Apart these flags, patch changes rwc->done to !page_mapcount()
instead of !page_mapped(). try_to_unmap() works on pte level, so we
really interested if this small pages is mapped, not compound page
it's part of.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
include/linux/huge_mm.h | 7 +++++++
include/linux/rmap.h | 3 +++
mm/huge_memory.c | 5 +----
mm/rmap.c | 24 ++++++++++++++++--------
4 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 459fd25b378e..c47067151ffd 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -111,6 +111,9 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
__split_huge_pmd(__vma, __pmd, __address); \
} while (0)
+
+void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address);
+
#if HPAGE_PMD_ORDER >= MAX_ORDER
#error "hugepages can't be allocated by the buddy allocator"
#endif
@@ -178,6 +181,10 @@ static inline int split_huge_page(struct page *page)
static inline void deferred_split_huge_page(struct page *page) {}
#define split_huge_pmd(__vma, __pmd, __address) \
do { } while (0)
+
+static inline void split_huge_pmd_address(struct vm_area_struct *vma,
+ unsigned long address) {}
+
static inline int hugepage_madvise(struct vm_area_struct *vma,
unsigned long *vm_flags, int advice)
{
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 23a03fbeef61..1fdde1ee7042 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -86,6 +86,7 @@ enum ttu_flags {
TTU_MIGRATION = 2, /* migration mode */
TTU_MUNLOCK = 4, /* munlock mode */
TTU_LZFREE = 8, /* lazy free mode */
+ TTU_SPLIT_HUGE_PMD = 16, /* split huge PMD if any */
TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
@@ -93,6 +94,8 @@ enum ttu_flags {
TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible
* and caller guarantees they will
* do a final flush if necessary */
+ TTU_RMAP_LOCKED = (1 << 12) /* do not grab rmap lock:
+ * caller holds it */
};
#ifdef CONFIG_MMU
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 581709e837b7..4213c76c8434 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2970,15 +2970,12 @@ out:
}
}
-static void split_huge_pmd_address(struct vm_area_struct *vma,
- unsigned long address)
+void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
- VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
-
pgd = pgd_offset(vma->vm_mm, address);
if (!pgd_present(*pgd))
return;
diff --git a/mm/rmap.c b/mm/rmap.c
index a9cffb784502..2cafd48caf85 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1435,6 +1435,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
goto out;
+ if (flags & TTU_SPLIT_HUGE_PMD)
+ split_huge_pmd_address(vma, address);
pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
goto out;
@@ -1580,10 +1582,10 @@ static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
return is_vma_temporary_stack(vma);
}
-static int page_not_mapped(struct page *page)
+static int page_mapcount_is_zero(struct page *page)
{
- return !page_mapped(page);
-};
+ return !page_mapcount(page);
+}
/**
* try_to_unmap - try to remove all page table mappings to a page
@@ -1610,12 +1612,10 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
struct rmap_walk_control rwc = {
.rmap_one = try_to_unmap_one,
.arg = &rp,
- .done = page_not_mapped,
+ .done = page_mapcount_is_zero,
.anon_lock = page_lock_anon_vma_read,
};
- VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
-
/*
* During exec, a temporary VMA is setup and later moved.
* The VMA is moved under the anon_vma lock but not the
@@ -1627,9 +1627,12 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
rwc.invalid_vma = invalid_migration_vma;
- ret = rmap_walk(page, &rwc);
+ if (flags & TTU_RMAP_LOCKED)
+ ret = rmap_walk_locked(page, &rwc);
+ else
+ ret = rmap_walk(page, &rwc);
- if (ret != SWAP_MLOCK && !page_mapped(page)) {
+ if (ret != SWAP_MLOCK && !page_mapcount(page)) {
ret = SWAP_SUCCESS;
if (rp.lazyfreed && !PageDirty(page))
ret = SWAP_LZFREE;
@@ -1637,6 +1640,11 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
return ret;
}
+static int page_not_mapped(struct page *page)
+{
+ return !page_mapped(page);
+};
+
/**
* try_to_munlock - try to munlock a page
* @page: the page to be munlocked
--
2.7.0
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