X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Frmap.c;h=0383acfcb0681a877f15f59d4d712980c37e1811;hb=d3ee1b405872214609868f3cde631ac157026dd0;hp=059774712c0889fbe1ff08aabc43f7593760baec;hpb=16f8c5b2e64dec7faa5d3c7e9bdf0765e864e481;p=linux-2.6

diff --git a/mm/rmap.c b/mm/rmap.c
index 059774712c..0383acfcb0 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -224,10 +224,14 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 /*
  * Check that @page is mapped at @address into @mm.
  *
+ * If @sync is false, page_check_address may perform a racy check to avoid
+ * the page table lock when the pte is not present (helpful when reclaiming
+ * highly shared pages).
+ *
  * On success returns with pte mapped and locked.
  */
 pte_t *page_check_address(struct page *page, struct mm_struct *mm,
-			  unsigned long address, spinlock_t **ptlp)
+			  unsigned long address, spinlock_t **ptlp, int sync)
 {
 	pgd_t *pgd;
 	pud_t *pud;
@@ -249,7 +253,7 @@ pte_t *page_check_address(struct page *page, struct mm_struct *mm,
 
 	pte = pte_offset_map(pmd, address);
 	/* Make a quick check before getting the lock */
-	if (!pte_present(*pte)) {
+	if (!sync && !pte_present(*pte)) {
 		pte_unmap(pte);
 		return NULL;
 	}
@@ -281,7 +285,7 @@ static int page_referenced_one(struct page *page,
 	if (address == -EFAULT)
 		goto out;
 
-	pte = page_check_address(page, mm, address, &ptl);
+	pte = page_check_address(page, mm, address, &ptl, 0);
 	if (!pte)
 		goto out;
 
@@ -450,7 +454,7 @@ static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
 	if (address == -EFAULT)
 		goto out;
 
-	pte = page_check_address(page, mm, address, &ptl);
+	pte = page_check_address(page, mm, address, &ptl, 1);
 	if (!pte)
 		goto out;
 
@@ -704,7 +708,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	if (address == -EFAULT)
 		goto out;
 
-	pte = page_check_address(page, mm, address, &ptl);
+	pte = page_check_address(page, mm, address, &ptl, 0);
 	if (!pte)
 		goto out;