dmapools: protect page_list walk in show_pools()

show_pools() walks the page_list of a pool w/o protection against the list
modifications in alloc/free.  Take pool->lock to avoid stomping into
nirvana.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/mm/dmapool.c b/mm/dmapool.c
index b1f0885dda22..3df063706f53 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -86,10 +86,12 @@ show_pools(struct device *dev, struct device_attribute *attr, char *buf)
                 unsigned pages = 0;
                 unsigned blocks = 0;
 
+                spin_lock_irq(&pool->lock);
                 list_for_each_entry(page, &pool->page_list, page_list) {
                         pages++;
                         blocks += page->in_use;
                 }
+                spin_unlock_irq(&pool->lock);
 
                 /* per-pool info, no real statistics yet */
                 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",