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

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Date:   Wed, 11 Sep 2019 20:31:11 -0600
From:   Yu Zhao <yuzhao@...gle.com>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Yu Zhao <yuzhao@...gle.com>
Subject: [PATCH v2 4/4] mm: lock slub page when listing objects

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@...gle.com>
---
 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));
 	put_map(map);
+
+	slab_unlock(page);
 }
 
 static int list_locations(struct kmem_cache *s, char *buf,
-- 
2.23.0.162.g0b9fbb3734-goog