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Message-ID: <20151106143707.GL29259@esperanza>
Date: Fri, 6 Nov 2015 17:37:07 +0300
From: Vladimir Davydov <vdavydov@...tuozzo.com>
To: "Kirill A. Shutemov" <kirill@...temov.name>
CC: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Sasha Levin <sasha.levin@...cle.com>,
Minchan Kim <minchan@...nel.org>,
<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
Subject: [PATCH] mm: add page_check_address_transhuge helper
page_referenced_one() and page_idle_clear_pte_refs_one() duplicate the
code for looking up pte of a (possibly transhuge) page. Move this code
to a new helper function, page_check_address_transhuge(), and make the
above mentioned functions use it.
This is just a cleanup, no functional changes are intended.
Signed-off-by: Vladimir Davydov <vdavydov@...tuozzo.com>
---
include/linux/rmap.h | 8 ++++
mm/page_idle.c | 62 ++++-------------------------
mm/rmap.c | 110 ++++++++++++++++++++++++++++++---------------------
3 files changed, 81 insertions(+), 99 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 853f4f3c6742..7b7ce0282c2d 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -217,6 +217,14 @@ static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
}
/*
+ * Used by idle page tracking to check if a page was referenced via page
+ * tables.
+ */
+bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
+ unsigned long address, pmd_t **pmdp,
+ pte_t **ptep, spinlock_t **ptlp);
+
+/*
* Used by swapoff to help locate where page is expected in vma.
*/
unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
diff --git a/mm/page_idle.c b/mm/page_idle.c
index 2c9ebe12b40d..374931f32ebc 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -55,70 +55,22 @@ static int page_idle_clear_pte_refs_one(struct page *page,
unsigned long addr, void *arg)
{
struct mm_struct *mm = vma->vm_mm;
- spinlock_t *ptl;
- pgd_t *pgd;
- pud_t *pud;
pmd_t *pmd;
pte_t *pte;
+ spinlock_t *ptl;
bool referenced = false;
- pgd = pgd_offset(mm, addr);
- if (!pgd_present(*pgd))
- return SWAP_AGAIN;
- pud = pud_offset(pgd, addr);
- if (!pud_present(*pud))
- return SWAP_AGAIN;
- pmd = pmd_offset(pud, addr);
-
- if (pmd_trans_huge(*pmd)) {
- ptl = pmd_lock(mm, pmd);
- if (!pmd_present(*pmd))
- goto unlock_pmd;
- if (unlikely(!pmd_trans_huge(*pmd))) {
- spin_unlock(ptl);
- goto map_pte;
- }
-
- if (pmd_page(*pmd) != page)
- goto unlock_pmd;
-
- referenced = pmdp_clear_young_notify(vma, addr, pmd);
- spin_unlock(ptl);
- goto found;
-unlock_pmd:
- spin_unlock(ptl);
+ if (!page_check_address_transhuge(page, mm, addr, &pmd, &pte, &ptl))
return SWAP_AGAIN;
- } else {
- pmd_t pmde = *pmd;
- barrier();
- if (!pmd_present(pmde) || pmd_trans_huge(pmde))
- return SWAP_AGAIN;
- }
-map_pte:
- pte = pte_offset_map(pmd, addr);
- if (!pte_present(*pte)) {
+ if (pte) {
+ referenced = ptep_clear_young_notify(vma, addr, pte);
pte_unmap(pte);
- return SWAP_AGAIN;
- }
-
- ptl = pte_lockptr(mm, pmd);
- spin_lock(ptl);
-
- if (!pte_present(*pte)) {
- pte_unmap_unlock(pte, ptl);
- return SWAP_AGAIN;
- }
+ } else
+ referenced = pmdp_clear_young_notify(vma, addr, pmd);
- /* THP can be referenced by any subpage */
- if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) {
- pte_unmap_unlock(pte, ptl);
- return SWAP_AGAIN;
- }
+ spin_unlock(ptl);
- referenced = ptep_clear_young_notify(vma, addr, pte);
- pte_unmap_unlock(pte, ptl);
-found:
if (referenced) {
clear_page_idle(page);
/*
diff --git a/mm/rmap.c b/mm/rmap.c
index 0837487d3737..7ac775e41820 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -796,48 +796,43 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
return 1;
}
-struct page_referenced_arg {
- int mapcount;
- int referenced;
- unsigned long vm_flags;
- struct mem_cgroup *memcg;
-};
/*
- * arg: page_referenced_arg will be passed
+ * Check that @page is mapped at @address into @mm. In contrast to
+ * page_check_address(), this function can handle transparent huge pages.
+ *
+ * On success returns true with pte mapped and locked. For transparent huge
+ * pages *@...p is set to NULL.
*/
-static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
- unsigned long address, void *arg)
+bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
+ unsigned long address, pmd_t **pmdp,
+ pte_t **ptep, spinlock_t **ptlp)
{
- struct mm_struct *mm = vma->vm_mm;
- spinlock_t *ptl;
- int referenced = 0;
- struct page_referenced_arg *pra = arg;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
+ spinlock_t *ptl;
if (unlikely(PageHuge(page))) {
/* when pud is not present, pte will be NULL */
pte = huge_pte_offset(mm, address);
if (!pte)
- return SWAP_AGAIN;
+ return false;
ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
+ pmd = NULL;
goto check_pte;
}
pgd = pgd_offset(mm, address);
if (!pgd_present(*pgd))
- return SWAP_AGAIN;
+ return false;
pud = pud_offset(pgd, address);
if (!pud_present(*pud))
- return SWAP_AGAIN;
+ return false;
pmd = pmd_offset(pud, address);
if (pmd_trans_huge(*pmd)) {
- int ret = SWAP_AGAIN;
-
ptl = pmd_lock(mm, pmd);
if (!pmd_present(*pmd))
goto unlock_pmd;
@@ -849,30 +844,22 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
if (pmd_page(*pmd) != page)
goto unlock_pmd;
- if (vma->vm_flags & VM_LOCKED) {
- pra->vm_flags |= VM_LOCKED;
- ret = SWAP_FAIL; /* To break the loop */
- goto unlock_pmd;
- }
-
- if (pmdp_clear_flush_young_notify(vma, address, pmd))
- referenced++;
- spin_unlock(ptl);
+ pte = NULL;
goto found;
unlock_pmd:
spin_unlock(ptl);
- return ret;
+ return false;
} else {
pmd_t pmde = *pmd;
barrier();
if (!pmd_present(pmde) || pmd_trans_huge(pmde))
- return SWAP_AGAIN;
+ return false;
}
map_pte:
pte = pte_offset_map(pmd, address);
if (!pte_present(*pte)) {
pte_unmap(pte);
- return SWAP_AGAIN;
+ return false;
}
ptl = pte_lockptr(mm, pmd);
@@ -881,35 +868,70 @@ check_pte:
if (!pte_present(*pte)) {
pte_unmap_unlock(pte, ptl);
- return SWAP_AGAIN;
+ return false;
}
/* THP can be referenced by any subpage */
if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) {
pte_unmap_unlock(pte, ptl);
- return SWAP_AGAIN;
+ return false;
}
+found:
+ *ptep = pte;
+ *pmdp = pmd;
+ *ptlp = ptl;
+ return true;
+}
+
+struct page_referenced_arg {
+ int mapcount;
+ int referenced;
+ unsigned long vm_flags;
+ struct mem_cgroup *memcg;
+};
+/*
+ * arg: page_referenced_arg will be passed
+ */
+static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, void *arg)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct page_referenced_arg *pra = arg;
+ pmd_t *pmd;
+ pte_t *pte;
+ spinlock_t *ptl;
+ int referenced = 0;
+
+ if (!page_check_address_transhuge(page, mm, address, &pmd, &pte, &ptl))
+ return SWAP_AGAIN;
if (vma->vm_flags & VM_LOCKED) {
- pte_unmap_unlock(pte, ptl);
+ if (pte)
+ pte_unmap(pte);
+ spin_unlock(ptl);
pra->vm_flags |= VM_LOCKED;
return SWAP_FAIL; /* To break the loop */
}
- if (ptep_clear_flush_young_notify(vma, address, pte)) {
- /*
- * Don't treat a reference through a sequentially read
- * mapping as such. If the page has been used in
- * another mapping, we will catch it; if this other
- * mapping is already gone, the unmap path will have
- * set PG_referenced or activated the page.
- */
- if (likely(!(vma->vm_flags & VM_SEQ_READ)))
+ if (pte) {
+ if (ptep_clear_flush_young_notify(vma, address, pte)) {
+ /*
+ * Don't treat a reference through a sequentially read
+ * mapping as such. If the page has been used in
+ * another mapping, we will catch it; if this other
+ * mapping is already gone, the unmap path will have
+ * set PG_referenced or activated the page.
+ */
+ if (likely(!(vma->vm_flags & VM_SEQ_READ)))
+ referenced++;
+ }
+ pte_unmap(pte);
+ } else {
+ if (pmdp_clear_flush_young_notify(vma, address, pmd))
referenced++;
}
- pte_unmap_unlock(pte, ptl);
+ spin_unlock(ptl);
-found:
if (referenced)
clear_page_idle(page);
if (test_and_clear_page_young(page))
--
2.1.4
--
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