+ lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update
has been added to the -mm tree.  Its filename is
     lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update.patch

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------------------------------------------------------
Subject: lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update
From: Jan Kara <jack@suse.cz>

below is an updated version of the fix.  The core of the fix is the same,
it just includes a few more comments updates and a check in
tag_pages_for_writeback() to avoid cycling indefinitely.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/radix-tree.c    |    2 ++
 mm/page-writeback.c |    3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff -puN lib/radix-tree.c~lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update lib/radix-tree.c
--- a/lib/radix-tree.c~lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update
+++ a/lib/radix-tree.c
@@ -625,6 +625,8 @@ EXPORT_SYMBOL(radix_tree_tag_get);
  *
  * The function returns number of leaves where the tag was set and sets
  * *first_indexp to the first unscanned index.
+ * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
+ * be prepared to handle that.
  */
 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
 		unsigned long *first_indexp, unsigned long last_index,
diff -puN mm/page-writeback.c~lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update mm/page-writeback.c
--- a/mm/page-writeback.c~lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update
+++ a/mm/page-writeback.c
@@ -836,7 +836,8 @@ void tag_pages_for_writeback(struct addr
 		spin_unlock_irq(&mapping->tree_lock);
 		WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH);
 		cond_resched();
-	} while (tagged >= WRITEBACK_TAG_BATCH);
+		/* We check 'start' to handle wrapping when end == ~0UL */
+	} while (tagged >= WRITEBACK_TAG_BATCH && start);
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);
 
_

Patches currently in -mm which might be from jack@suse.cz are

origin.patch
lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged.patch
lib-radix-treec-fix-overflow-in-radix_tree_range_tag_if_tagged-update.patch
linux-next.patch
aio-do-not-return-erestartsys-and-friends-from-aio.patch
reiser4.patch