[PATCH 3.4 03/24] mm: __set_page_dirty uses spin_lock_irqsave instead of spin_lock_irq

Greg Kroah-Hartman
2014-02-18T23:31:13Z

From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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]
migrate_page_copy
clear_page_dirty_for_io
set_page_dirty
__set_page_dirty_buffers
__set_page_dirty
spin_lock_irq

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@jp.fujitsu.com>
Reported-by: David Rientjes rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/buffer.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -613,14 +613,16 @@ 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);
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);
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
}