Commit 96d8dbb6 authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm, slab, kasan: replace kasan_never_merge() with SLAB_NO_MERGE 



The SLAB_KASAN flag prevents merging of caches in some configurations,
which is handled in a rather complicated way via kasan_never_merge().
Since we now have a generic SLAB_NO_MERGE flag, we can instead use it
for KASAN caches in addition to SLAB_KASAN in those configurations,
and simplify the SLAB_NEVER_MERGE handling.

Tested-by: default avatarXiongwei Song <xiongwei.song@windriver.com>
Reviewed-by: default avatarChengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Tested-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent cc61eb85

include/linux/kasan.h

+0 −6
Original line number Diff line number Diff line
@@ -429,7 +429,6 @@ struct kasan_cache { 
};



size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object);

slab_flags_t kasan_never_merge(void);

void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,

			slab_flags_t *flags);
@@ -446,11 +445,6 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache, 
{

	return 0;

}

/* And thus nothing prevents cache merging. */

static inline slab_flags_t kasan_never_merge(void)

{

	return 0;

}

/* And no cache-related metadata initialization is required. */

static inline void kasan_cache_create(struct kmem_cache *cache,

				      unsigned int *size,

mm/kasan/generic.c

+6 −16
Original line number Diff line number Diff line
@@ -334,14 +334,6 @@ DEFINE_ASAN_SET_SHADOW(f3); 
DEFINE_ASAN_SET_SHADOW(f5);

DEFINE_ASAN_SET_SHADOW(f8);



/* Only allow cache merging when no per-object metadata is present. */

slab_flags_t kasan_never_merge(void)

{

	if (!kasan_requires_meta())

		return 0;

	return SLAB_KASAN;

}



/*

 * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.

 * For larger allocations larger redzones are used.
@@ -370,15 +362,13 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, 
		return;



	/*

	 * SLAB_KASAN is used to mark caches that are sanitized by KASAN

	 * and that thus have per-object metadata.

	 * Currently this flag is used in two places:

	 * 1. In slab_ksize() to account for per-object metadata when

	 *    calculating the size of the accessible memory within the object.

	 * 2. In slab_common.c via kasan_never_merge() to prevent merging of

	 *    caches with per-object metadata.

	 * SLAB_KASAN is used to mark caches that are sanitized by KASAN and

	 * that thus have per-object metadata. Currently, this flag is used in

	 * slab_ksize() to account for per-object metadata when calculating the

	 * size of the accessible memory within the object. Additionally, we use

	 * SLAB_NO_MERGE to prevent merging of caches with per-object metadata.

	 */

	*flags |= SLAB_KASAN;

	*flags |= SLAB_KASAN | SLAB_NO_MERGE;



	ok_size = *size;

mm/slab_common.c

+1 −1
Original line number Diff line number Diff line
@@ -50,7 +50,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 
 */

#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \

		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \

		SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge())

		SLAB_FAILSLAB | SLAB_NO_MERGE)



#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \

			 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)