X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Fswapfile.c;h=bd1bb59203065621e561900b125c017bfe65054d;hb=e6dd731c75cba986a485924f908e6e05b088ea9e;hp=fddc4cc4149bce91491ee9d08aa8099969793236;hpb=8a9f3ccd24741b50200c3f33d62534c7271f3dfc;p=linux-2.6

diff --git a/mm/swapfile.c b/mm/swapfile.c
index fddc4cc414..bd1bb59203 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -507,11 +507,23 @@ unsigned int count_swap_pages(int type, int free)
  * just let do_wp_page work it out if a write is requested later - to
  * force COW, vm_page_prot omits write permission from any private vma.
  */
-static int unuse_pte(struct vm_area_struct *vma, pte_t *pte,
+static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 		unsigned long addr, swp_entry_t entry, struct page *page)
 {
-	if (mem_cgroup_charge(page, vma->vm_mm))
-		return -ENOMEM;
+	spinlock_t *ptl;
+	pte_t *pte;
+	int ret = 1;
+
+	if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
+		ret = -ENOMEM;
+
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
+		if (ret > 0)
+			mem_cgroup_uncharge_page(page);
+		ret = 0;
+		goto out;
+	}
 
 	inc_mm_counter(vma->vm_mm, anon_rss);
 	get_page(page);
@@ -524,7 +536,9 @@ static int unuse_pte(struct vm_area_struct *vma, pte_t *pte,
 	 * immediately swapped out again after swapon.
 	 */
 	activate_page(page);
-	return 1;
+out:
+	pte_unmap_unlock(pte, ptl);
+	return ret;
 }
 
 static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
@@ -533,21 +547,33 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 {
 	pte_t swp_pte = swp_entry_to_pte(entry);
 	pte_t *pte;
-	spinlock_t *ptl;
 	int ret = 0;
 
-	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	/*
+	 * We don't actually need pte lock while scanning for swp_pte: since
+	 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
+	 * page table while we're scanning; though it could get zapped, and on
+	 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
+	 * of unmatched parts which look like swp_pte, so unuse_pte must
+	 * recheck under pte lock.  Scanning without pte lock lets it be
+	 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
+	 */
+	pte = pte_offset_map(pmd, addr);
 	do {
 		/*
 		 * swapoff spends a _lot_ of time in this loop!
 		 * Test inline before going to call unuse_pte.
 		 */
 		if (unlikely(pte_same(*pte, swp_pte))) {
-			ret = unuse_pte(vma, pte++, addr, entry, page);
-			break;
+			pte_unmap(pte);
+			ret = unuse_pte(vma, pmd, addr, entry, page);
+			if (ret)
+				goto out;
+			pte = pte_offset_map(pmd, addr);
 		}
 	} while (pte++, addr += PAGE_SIZE, addr != end);
-	pte_unmap_unlock(pte - 1, ptl);
+	pte_unmap(pte - 1);
+out:
 	return ret;
 }
 
@@ -1368,7 +1394,7 @@ static int swap_show(struct seq_file *swap, void *v)
 	}
 
 	file = ptr->swap_file;
-	len = seq_path(swap, file->f_path.mnt, file->f_path.dentry, " \t\n\\");
+	len = seq_path(swap, &file->f_path, " \t\n\\");
 	seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
 		       len < 40 ? 40 - len : 1, " ",
 		       S_ISBLK(file->f_path.dentry->d_inode->i_mode) ?
@@ -1400,11 +1426,7 @@ static const struct file_operations proc_swaps_operations = {
 
 static int __init procswaps_init(void)
 {
-	struct proc_dir_entry *entry;
-
-	entry = create_proc_entry("swaps", 0, NULL);
-	if (entry)
-		entry->proc_fops = &proc_swaps_operations;
+	proc_create("swaps", 0, NULL, &proc_swaps_operations);
 	return 0;
 }
 __initcall(procswaps_init);
@@ -1556,6 +1578,14 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 		error = -EINVAL;
 		goto bad_swap;
 	case 2:
+		/* swap partition endianess hack... */
+		if (swab32(swap_header->info.version) == 1) {
+			swab32s(&swap_header->info.version);
+			swab32s(&swap_header->info.last_page);
+			swab32s(&swap_header->info.nr_badpages);
+			for (i = 0; i < swap_header->info.nr_badpages; i++)
+				swab32s(&swap_header->info.badpages[i]);
+		}
 		/* Check the swap header's sub-version and the size of
                    the swap file and bad block lists */
 		if (swap_header->info.version != 1) {