Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "Three fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/ksm.c: don't WARN if page is still mapped in remove_stable_node()
  mm/memory_hotplug: don't access uninitialized memmaps in shrink_zone_span()
  Revert "fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()"

3 files changed, 53 insertions, 33 deletions

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index d8507972ee13..90c830e3758e 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -1490,6 +1490,18 @@ static int ocfs2_xa_check_space(struct ocfs2_xa_loc *loc,
 	return loc->xl_ops->xlo_check_space(loc, xi);
 }
 
+static void ocfs2_xa_add_entry(struct ocfs2_xa_loc *loc, u32 name_hash)
+{
+	loc->xl_ops->xlo_add_entry(loc, name_hash);
+	loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash);
+	/*
+	 * We can't leave the new entry's xe_name_offset at zero or
+	 * add_namevalue() will go nuts.  We set it to the size of our
+	 * storage so that it can never be less than any other entry.
+	 */
+	loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size);
+}
+
 static void ocfs2_xa_add_namevalue(struct ocfs2_xa_loc *loc,
 				   struct ocfs2_xattr_info *xi)
 {
@@ -2121,31 +2133,29 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc,
 	if (rc)
 		goto out;
 
-	if (!loc->xl_entry) {
-		rc = -EINVAL;
-		goto out;
-	}
-
-	if (ocfs2_xa_can_reuse_entry(loc, xi)) {
-		orig_value_size = loc->xl_entry->xe_value_size;
-		rc = ocfs2_xa_reuse_entry(loc, xi, ctxt);
-		if (rc)
-			goto out;
-		goto alloc_value;
-	}
+	if (loc->xl_entry) {
+		if (ocfs2_xa_can_reuse_entry(loc, xi)) {
+			orig_value_size = loc->xl_entry->xe_value_size;
+			rc = ocfs2_xa_reuse_entry(loc, xi, ctxt);
+			if (rc)
+				goto out;
+			goto alloc_value;
+		}
 
-	if (!ocfs2_xattr_is_local(loc->xl_entry)) {
-		orig_clusters = ocfs2_xa_value_clusters(loc);
-		rc = ocfs2_xa_value_truncate(loc, 0, ctxt);
-		if (rc) {
-			mlog_errno(rc);
-			ocfs2_xa_cleanup_value_truncate(loc,
-							"overwriting",
-							orig_clusters);
-			goto out;
+		if (!ocfs2_xattr_is_local(loc->xl_entry)) {
+			orig_clusters = ocfs2_xa_value_clusters(loc);
+			rc = ocfs2_xa_value_truncate(loc, 0, ctxt);
+			if (rc) {
+				mlog_errno(rc);
+				ocfs2_xa_cleanup_value_truncate(loc,
+								"overwriting",
+								orig_clusters);
+				goto out;
+			}
 		}
-	}
-	ocfs2_xa_wipe_namevalue(loc);
+		ocfs2_xa_wipe_namevalue(loc);
+	} else
+		ocfs2_xa_add_entry(loc, name_hash);
 
 	/*
 	 * If we get here, we have a blank entry.  Fill it.  We grow our
diff --git a/mm/ksm.c b/mm/ksm.c
index dbee2eb4dd05..7905934cd3ad 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -885,13 +885,13 @@ static int remove_stable_node(struct stable_node *stable_node)
 		return 0;
 	}
 
-	if (WARN_ON_ONCE(page_mapped(page))) {
-		/*
-		 * This should not happen: but if it does, just refuse to let
-		 * merge_across_nodes be switched - there is no need to panic.
-		 */
-		err = -EBUSY;
-	} else {
+	/*
+	 * Page could be still mapped if this races with __mmput() running in
+	 * between ksm_exit() and exit_mmap(). Just refuse to let
+	 * merge_across_nodes/max_page_sharing be switched.
+	 */
+	err = -EBUSY;
+	if (!page_mapped(page)) {
 		/*
 		 * The stable node did not yet appear stale to get_ksm_page(),
 		 * since that allows for an unmapped ksm page to be recognized
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3b62a9ff8ea0..f307bd82d750 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -331,7 +331,7 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
 				     unsigned long end_pfn)
 {
 	for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) {
-		if (unlikely(!pfn_valid(start_pfn)))
+		if (unlikely(!pfn_to_online_page(start_pfn)))
 			continue;
 
 		if (unlikely(pfn_to_nid(start_pfn) != nid))
@@ -356,7 +356,7 @@ static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
 	/* pfn is the end pfn of a memory section. */
 	pfn = end_pfn - 1;
 	for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) {
-		if (unlikely(!pfn_valid(pfn)))
+		if (unlikely(!pfn_to_online_page(pfn)))
 			continue;
 
 		if (unlikely(pfn_to_nid(pfn) != nid))
@@ -415,7 +415,7 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
 	 */
 	pfn = zone_start_pfn;
 	for (; pfn < zone_end_pfn; pfn += PAGES_PER_SUBSECTION) {
-		if (unlikely(!pfn_valid(pfn)))
+		if (unlikely(!pfn_to_online_page(pfn)))
 			continue;
 
 		if (page_zone(pfn_to_page(pfn)) != zone)
@@ -471,6 +471,16 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn,
 	struct pglist_data *pgdat = zone->zone_pgdat;
 	unsigned long flags;
 
+#ifdef CONFIG_ZONE_DEVICE
+	/*
+	 * Zone shrinking code cannot properly deal with ZONE_DEVICE. So
+	 * we will not try to shrink the zones - which is okay as
+	 * set_zone_contiguous() cannot deal with ZONE_DEVICE either way.
+	 */
+	if (zone_idx(zone) == ZONE_DEVICE)
+		return;
+#endif
+
 	pgdat_resize_lock(zone->zone_pgdat, &flags);
 	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
 	update_pgdat_span(pgdat);