Commit 55860d96 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Linus Torvalds
Browse files

slub: cure list_slab_objects() from double fix 

According to Christopher Lameter two fixes have been merged for the same
problem.  As far as I can tell, the code does not acquire the list_lock
and invoke kmalloc().  list_slab_objects() misses an unlock (the
counterpart to get_map()) and the memory allocated in free_partial()
isn't used.

Revert the mentioned commit.

Link: http://lkml.kernel.org/r/20200618201234.795692-1-bigeasy@linutronix.de
Fixes: aa456c7a ("slub: remove kmalloc under list_lock from list_slab_objects() V2")
Link: https://lkml.kernel.org/r/alpine.DEB.2.22.394.2006181501480.12014@www.lameter.com


Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8982ae52

mm/slub.c

+4 −15
Original line number Diff line number Diff line
@@ -3766,15 +3766,13 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags) 
}



static void list_slab_objects(struct kmem_cache *s, struct page *page,

			      const char *text, unsigned long *map)

			      const char *text)

{

#ifdef CONFIG_SLUB_DEBUG

	void *addr = page_address(page);

	unsigned long *map;

	void *p;



	if (!map)

		return;



	slab_err(s, page, text, s->name);

	slab_lock(page);
@@ -3786,6 +3784,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page, 
			print_tracking(s, p);

		}

	}

	put_map(map);

	slab_unlock(page);

#endif

}
@@ -3799,11 +3798,6 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n) 
{

	LIST_HEAD(discard);

	struct page *page, *h;

	unsigned long *map = NULL;



#ifdef CONFIG_SLUB_DEBUG

	map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL);

#endif



	BUG_ON(irqs_disabled());

	spin_lock_irq(&n->list_lock);
@@ -3813,16 +3807,11 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n) 
			list_add(&page->slab_list, &discard);

		} else {

			list_slab_objects(s, page,

			  "Objects remaining in %s on __kmem_cache_shutdown()",

			  map);

			  "Objects remaining in %s on __kmem_cache_shutdown()");

		}

	}

	spin_unlock_irq(&n->list_lock);



#ifdef CONFIG_SLUB_DEBUG

	bitmap_free(map);

#endif



	list_for_each_entry_safe(page, h, &discard, slab_list)

		discard_slab(s, page);

}