[PATCH v2 4/4] mm: lock slub page when listing objects

From: Yu Zhao
Date: Wed Sep 11 2019 - 22:31:28 EST

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

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 baa60dd73942..1c9726c28f0b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4608,11 +4608,15 @@ static void process_slab(struct loc_track *t, struct kmem_cache *s,
void *p;
unsigned long *map;

+ slab_lock(page);
map = get_map(s, page);
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,