[RESEND PATCH] mm: Use spin_lock_irqsave in __set_page_dirty_nobuffers

[Andy Grover <andy.grover@oracle.com>]

RDS is calling set_page_dirty from interrupt context, which
ends up calling this function. Using irqsave ensures irqs
are not re-enabled by this function.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
---
 mm/page-writeback.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b840afa..c6c381b 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1155,11 +1155,12 @@ int __set_page_dirty_nobuffers(struct page *page)
 	if (!TestSetPageDirty(page)) {
 		struct address_space *mapping = page_mapping(page);
 		struct address_space *mapping2;
+		unsigned long flags;
 
 		if (!mapping)
 			return 1;
 
-		spin_lock_irq(&mapping->tree_lock);
+		spin_lock_irqsave(&mapping->tree_lock, flags);
 		mapping2 = page_mapping(page);
 		if (mapping2) { /* Race with truncate? */
 			BUG_ON(mapping2 != mapping);
@@ -1168,7 +1169,7 @@ int __set_page_dirty_nobuffers(struct page *page)
 			radix_tree_tag_set(&mapping->page_tree,
 				page_index(page), PAGECACHE_TAG_DIRTY);
 		}
-		spin_unlock_irq(&mapping->tree_lock);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
 		if (mapping->host) {
 			/* !PageAnon && !swapper_space */
 			__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
-- 
1.7.1

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