X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Fmigrate.c;h=55bd355d170d055907c407f0c93d98dcb6e9e555;hb=7a36a752d006f6874049da510297eeb7f09d92a7;hp=a73504ff5ab982007b2e0355e49f0dedcac65899;hpb=f0f1b3364ae7f48084bdf2837fb979ff59622523;p=linux-2.6

diff --git a/mm/migrate.c b/mm/migrate.c
index a73504ff5a..55bd355d17 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -9,7 +9,7 @@
  * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
  * Hirokazu Takahashi <taka@valinux.co.jp>
  * Dave Hansen <haveblue@us.ibm.com>
- * Christoph Lameter <clameter@sgi.com>
+ * Christoph Lameter
  */
 
 #include <linux/migrate.h>
@@ -153,11 +153,6 @@ static void remove_migration_pte(struct vm_area_struct *vma,
  		return;
  	}
 
-	if (mem_cgroup_charge(new, mm, GFP_KERNEL)) {
-		pte_unmap(ptep);
-		return;
-	}
-
  	ptl = pte_lockptr(mm, pmd);
  	spin_lock(ptl);
 	pte = *ptep;
@@ -169,6 +164,20 @@ static void remove_migration_pte(struct vm_area_struct *vma,
 	if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
 		goto out;
 
+	/*
+	 * Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge.
+	 * Failure is not an option here: we're now expected to remove every
+	 * migration pte, and will cause crashes otherwise.  Normally this
+	 * is not an issue: mem_cgroup_prepare_migration bumped up the old
+	 * page_cgroup count for safety, that's now attached to the new page,
+	 * so this charge should just be another incrementation of the count,
+	 * to keep in balance with rmap.c's mem_cgroup_uncharging.  But if
+	 * there's been a force_empty, those reference counts may no longer
+	 * be reliable, and this charge can actually fail: oh well, we don't
+	 * make the situation any worse by proceeding as if it had succeeded.
+	 */
+	mem_cgroup_charge(new, mm, GFP_ATOMIC);
+
 	get_page(new);
 	pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
 	if (is_write_migration_entry(entry))
@@ -374,7 +383,14 @@ static void migrate_page_copy(struct page *newpage, struct page *page)
 
 	if (PageDirty(page)) {
 		clear_page_dirty_for_io(page);
-		set_page_dirty(newpage);
+		/*
+		 * Want to mark the page and the radix tree as dirty, and
+		 * redo the accounting that clear_page_dirty_for_io undid,
+		 * but we can't use set_page_dirty because that function
+		 * is actually a signal that all of the page has become dirty.
+		 * Wheras only part of our page may be dirty.
+		 */
+		__set_page_dirty_nobuffers(newpage);
  	}
 
 #ifdef CONFIG_SWAP
@@ -849,6 +865,11 @@ static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
 			goto set_status;
 
 		page = follow_page(vma, pp->addr, FOLL_GET);
+
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto set_status;
+
 		err = -ENOENT;
 		if (!page)
 			goto set_status;
@@ -912,6 +933,11 @@ static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
 			goto set_status;
 
 		page = follow_page(vma, pm->addr, 0);
+
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto set_status;
+
 		err = -ENOENT;
 		/* Use PageReserved to check for zero page */
 		if (!page || PageReserved(page))