[PATCH 3.2 091/200] mm: __set_page_dirty uses spin_lock_irqsave instead of spin_lock_irq

From: Ben Hutchings
Date: Sun Mar 30 2014 - 20:41:00 EST

3.2.56-rc1 review patch. If anyone has any objections, please let me know.


From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>

commit 227d53b397a32a7614667b3ecaf1d89902fb6c12 upstream.

To use spin_{un}lock_irq is dangerous if caller disabled interrupt.
During aio buffer migration, we have a possibility to see the following
call stack.

aio_migratepage [disable interrupt]

This mean, current aio migration is a deadlockable. spin_lock_irqsave
is a safer alternative and we should use it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Reported-by: David Rientjes rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
fs/buffer.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -663,14 +663,16 @@ EXPORT_SYMBOL(mark_buffer_dirty_inode);
static void __set_page_dirty(struct page *page,
struct address_space *mapping, int warn)
- spin_lock_irq(&mapping->tree_lock);
+ unsigned long flags;
+ spin_lock_irqsave(&mapping->tree_lock, flags);
if (page->mapping) { /* Race with truncate? */
WARN_ON_ONCE(warn && !PageUptodate(page));
account_page_dirtied(page, mapping);
page_index(page), PAGECACHE_TAG_DIRTY);
- spin_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irqrestore(&mapping->tree_lock, flags);
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);

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