[PATCH 3/3] mm: lock slub page when listing objects

From: Yu Zhao
Date: Wed Sep 11 2019 - 20:30:08 EST

Though I have no idea what the side effect of a race would be,
apparently we want to prevent the free list from being changed
while debugging objects in general.

Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
mm/slub.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index f28072c9f2ce..2734a092bbff 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4594,10 +4594,14 @@ static void process_slab(struct loc_track *t, struct kmem_cache *s,
void *addr = page_address(page);
void *p;

+ slab_lock(page);
get_map(s, page, map);
for_each_object(p, s, addr, page->objects)
if (!test_bit(slab_index(p, s, addr), map))
add_location(t, s, get_track(s, p, alloc));
+ slab_unlock(page);

static int list_locations(struct kmem_cache *s, char *buf,