From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxx>
Reported-by: David Rientjes rientjes@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/buffer.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN fs/buffer.c~mm-__set_page_dirty-uses-spin_lock_irqsave-instead-of-spin_lock_irq fs/buffer.c
--- a/fs/buffer.c~mm-__set_page_dirty-uses-spin_lock_irqsave-instead-of-spin_lock_irq
+++ a/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);
}
_
--
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