X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Fmigrate.c;h=07f22d4a431f5ce63303632749453e9459ece1ee;hb=13808910713a98cc1159291e62cdfec92cc94d05;hp=34d8ada053e4562a3a7d216a544b4d9195741c16;hpb=39fe5434cb9de5da40510028b17b96bc4eb312b3;p=linux-2.6

diff --git a/mm/migrate.c b/mm/migrate.c
index 34d8ada053..07f22d4a43 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -49,9 +49,8 @@ int isolate_lru_page(struct page *page, struct list_head *pagelist)
 		struct zone *zone = page_zone(page);
 
 		spin_lock_irq(&zone->lru_lock);
-		if (PageLRU(page)) {
+		if (PageLRU(page) && get_page_unless_zero(page)) {
 			ret = 0;
-			get_page(page);
 			ClearPageLRU(page);
 			if (PageActive(page))
 				del_page_from_active_list(zone, page);
@@ -612,6 +611,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 	int rc = 0;
 	int *result = NULL;
 	struct page *newpage = get_new_page(page, private, &result);
+	int rcu_locked = 0;
 
 	if (!newpage)
 		return -ENOMEM;
@@ -632,18 +632,41 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
 			goto unlock;
 		wait_on_page_writeback(page);
 	}
-
 	/*
-	 * Establish migration ptes or remove ptes
+	 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
+	 * we cannot notice that anon_vma is freed while we migrates a page.
+	 * This rcu_read_lock() delays freeing anon_vma pointer until the end
+	 * of migration. File cache pages are no problem because of page_lock()
+	 * File Caches may use write_page() or lock_page() in migration, then,
+	 * just care Anon page here.
+	 */
+	if (PageAnon(page)) {
+		rcu_read_lock();
+		rcu_locked = 1;
+	}
+	/*
+	 * This is a corner case handling.
+	 * When a new swap-cache is read into, it is linked to LRU
+	 * and treated as swapcache but has no rmap yet.
+	 * Calling try_to_unmap() against a page->mapping==NULL page is
+	 * BUG. So handle it here.
 	 */
+	if (!page->mapping)
+		goto rcu_unlock;
+	/* Establish migration ptes or remove ptes */
 	try_to_unmap(page, 1);
+
 	if (!page_mapped(page))
 		rc = move_to_new_page(newpage, page);
 
 	if (rc)
 		remove_migration_ptes(page, page);
+rcu_unlock:
+	if (rcu_locked)
+		rcu_read_unlock();
 
 unlock:
+
 	unlock_page(page);
 
 	if (rc != -EAGAIN) {
@@ -949,7 +972,7 @@ asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
 	 * array. Return various errors if the user did something wrong.
 	 */
 	for (i = 0; i < nr_pages; i++) {
-		const void *p;
+		const void __user *p;
 
 		err = -EFAULT;
 		if (get_user(p, pages + i))