mm: __set_page_dirty uses spin_lock_irqsave instead of spin_lock_irq

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 651dba10b9c2..27265a8b43c1 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -654,14 +654,16 @@ 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);
 }