2014-02-04 16:59:09

by KOSAKI Motohiro

Subject: [PATCH] __set_page_dirty uses spin_lock_irqsave instead of spin_lock_irq

From: KOSAKI Motohiro <[email protected]>

To use spin_{un}lock_irq is dangerous if caller disabled interrupt.
spin_lock_irqsave is a safer alternative. Luckily, now there is no
caller that has such usage but it would be nice to fix.

Reported-by: David Rientjes [email protected]>
Signed-off-by: KOSAKI Motohiro <[email protected]>
---
fs/buffer.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 651dba1..27265a8 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);
}

--
1.7.1

2014-02-04 17:02:52

by KOSAKI Motohiro

Subject: Re: [PATCH] __set_page_dirty uses spin_lock_irqsave instead of spin_lock_irq

On Tue, Feb 4, 2014 at 11:58 AM, <[email protected]> wrote:
> From: KOSAKI Motohiro <[email protected]>
>
> To use spin_{un}lock_irq is dangerous if caller disabled interrupt.
> spin_lock_irqsave is a safer alternative. Luckily, now there is no
> caller that has such usage but it would be nice to fix.
>
> Reported-by: David Rientjes [email protected]>
> Signed-off-by: KOSAKI Motohiro <[email protected]>

Self Nack this. There IS a caller and we should send this to stable.
I'll respin.