[PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

A group of Linux kernel hackers reported chasing a bug that resulted
from their assumption that SLAB_DESTROY_BY_RCU provided an existence
guarantee, that is, that no block from such a slab would be reallocated
during an RCU read-side critical section.  Of course, that is not the
case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
slab of blocks.

However, there is a phrase for this, namely "type safety".  This commit
therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
to avoid future instances of this sort of confusion.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/Documentation/RCU/00-INDEX b/Documentation/RCU/00-INDEX
index f773a264ae02..1672573b037a 100644
--- a/Documentation/RCU/00-INDEX
+++ b/Documentation/RCU/00-INDEX
@@ -17,7 +17,7 @@ rcu_dereference.txt
 rcubarrier.txt
 	- RCU and Unloadable Modules
 rculist_nulls.txt
-	- RCU list primitives for use with SLAB_DESTROY_BY_RCU
+	- RCU list primitives for use with SLAB_TYPESAFE_BY_RCU
 rcuref.txt
 	- Reference-count design for elements of lists/arrays protected by RCU
 rcu.txt
diff --git a/Documentation/RCU/rculist_nulls.txt b/Documentation/RCU/rculist_nulls.txt
index 18f9651ff23d..8151f0195f76 100644
--- a/Documentation/RCU/rculist_nulls.txt
+++ b/Documentation/RCU/rculist_nulls.txt
@@ -1,5 +1,5 @@
 Using hlist_nulls to protect read-mostly linked lists and
-objects using SLAB_DESTROY_BY_RCU allocations.
+objects using SLAB_TYPESAFE_BY_RCU allocations.
 
 Please read the basics in Documentation/RCU/listRCU.txt
 
@@ -7,7 +7,7 @@ Using special makers (called 'nulls') is a convenient way
 to solve following problem :
 
 A typical RCU linked list managing objects which are
-allocated with SLAB_DESTROY_BY_RCU kmem_cache can
+allocated with SLAB_TYPESAFE_BY_RCU kmem_cache can
 use following algos :
 
 1) Lookup algo
@@ -96,7 +96,7 @@ unlock_chain(); // typically a spin_unlock()
 3) Remove algo
 --------------
 Nothing special here, we can use a standard RCU hlist deletion.
-But thanks to SLAB_DESTROY_BY_RCU, beware a deleted object can be reused
+But thanks to SLAB_TYPESAFE_BY_RCU, beware a deleted object can be reused
 very very fast (before the end of RCU grace period)
 
 if (put_last_reference_on(obj) {
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 5cbd8b2395b8..12374fa4cff1 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -925,7 +925,7 @@ d.	Do you need RCU grace periods to complete even in the face
 
 e.	Is your workload too update-intensive for normal use of
 	RCU, but inappropriate for other synchronization mechanisms?
-	If so, consider SLAB_DESTROY_BY_RCU.  But please be careful!
+	If so, consider SLAB_TYPESAFE_BY_RCU.  But please be careful!
 
 f.	Do you need read-side critical sections that are respected
 	even though they are in the middle of the idle loop, during
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3dd7fc662859..3871ca092aa6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4541,7 +4541,7 @@ i915_gem_load_init(struct drm_device *dev)
 	dev_priv->requests = KMEM_CACHE(drm_i915_gem_request,
 					SLAB_HWCACHE_ALIGN |
 					SLAB_RECLAIM_ACCOUNT |
-					SLAB_DESTROY_BY_RCU);
+					SLAB_TYPESAFE_BY_RCU);
 	if (!dev_priv->requests)
 		goto err_vmas;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index d229f47d1028..50d1075c9dab 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -504,7 +504,7 @@ static inline struct drm_i915_gem_request *
 __i915_gem_active_get_rcu(const struct i915_gem_active *active)
 {
 	/* Performing a lockless retrieval of the active request is super
-	 * tricky. SLAB_DESTROY_BY_RCU merely guarantees that the backing
+	 * tricky. SLAB_TYPESAFE_BY_RCU merely guarantees that the backing
 	 * slab of request objects will not be freed whilst we hold the
 	 * RCU read lock. It does not guarantee that the request itself
 	 * will not be freed and then *reused*. Viz,
diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
index 12647af5a336..e7fb47e84a93 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
@@ -1071,7 +1071,7 @@ int ldlm_init(void)
 	ldlm_lock_slab = kmem_cache_create("ldlm_locks",
 					   sizeof(struct ldlm_lock), 0,
 					   SLAB_HWCACHE_ALIGN |
-					   SLAB_DESTROY_BY_RCU, NULL);
+					   SLAB_TYPESAFE_BY_RCU, NULL);
 	if (!ldlm_lock_slab) {
 		kmem_cache_destroy(ldlm_resource_slab);
 		return -ENOMEM;
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index a097048ed1a3..8d0cbcc4c877 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2340,7 +2340,7 @@ static int jbd2_journal_init_journal_head_cache(void)
 	jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
 				sizeof(struct journal_head),
 				0,		/* offset */
-				SLAB_TEMPORARY | SLAB_DESTROY_BY_RCU,
+				SLAB_TEMPORARY | SLAB_TYPESAFE_BY_RCU,
 				NULL);		/* ctor */
 	retval = 0;
 	if (!jbd2_journal_head_cache) {
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 270221fcef42..7e3d71109f51 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -38,7 +38,7 @@ void signalfd_cleanup(struct sighand_struct *sighand)
 	/*
 	 * The lockless check can race with remove_wait_queue() in progress,
 	 * but in this case its caller should run under rcu_read_lock() and
-	 * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
+	 * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
 	 */
 	if (likely(!waitqueue_active(wqh)))
 		return;
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index d51a7d23c358..236fc0dbef39 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -229,7 +229,7 @@ static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)
  *
  * Function returns NULL if no refcount could be obtained, or the fence.
  * This function handles acquiring a reference to a fence that may be
- * reallocated within the RCU grace period (such as with SLAB_DESTROY_BY_RCU),
+ * reallocated within the RCU grace period (such as with SLAB_TYPESAFE_BY_RCU),
  * so long as the caller is using RCU on the pointer to the fence.
  *
  * An alternative mechanism is to employ a seqlock to protect a bunch of
@@ -257,7 +257,7 @@ dma_fence_get_rcu_safe(struct dma_fence * __rcu *fencep)
 		 * have successfully acquire a reference to it. If it no
 		 * longer matches, we are holding a reference to some other
 		 * reallocated pointer. This is possible if the allocator
-		 * is using a freelist like SLAB_DESTROY_BY_RCU where the
+		 * is using a freelist like SLAB_TYPESAFE_BY_RCU where the
 		 * fence remains valid for the RCU grace period, but it
 		 * may be reallocated. When using such allocators, we are
 		 * responsible for ensuring the reference we get is to
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 084b12bad198..708d5b1dc439 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -28,7 +28,7 @@
 #define SLAB_STORE_USER		0x00010000UL	/* DEBUG: Store the last owner for bug hunting */
 #define SLAB_PANIC		0x00040000UL	/* Panic if kmem_cache_create() fails */
 /*
- * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
+ * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
  *
  * This delays freeing the SLAB page by a grace period, it does _NOT_
  * delay object freeing. This means that if you do kmem_cache_free()
@@ -62,7 +62,7 @@
  * rcu_read_lock before reading the address, then rcu_read_unlock after
  * taking the spinlock within the structure expected at that address.
  */
-#define SLAB_DESTROY_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
+#define SLAB_TYPESAFE_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
 #define SLAB_MEM_SPREAD		0x00100000UL	/* Spread some memory over cpuset */
 #define SLAB_TRACE		0x00200000UL	/* Trace allocations and frees */
 
diff --git a/include/net/sock.h b/include/net/sock.h
index f0e867f58722..981b0cad8358 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -989,7 +989,7 @@ struct raw_hashinfo;
 struct module;
 
 /*
- * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
+ * caches using SLAB_TYPESAFE_BY_RCU should let .next pointer from nulls nodes
  * un-modified. Special care is taken when initializing object to zero.
  */
 static inline void sk_prot_clear_nulls(struct sock *sk, int size)
diff --git a/kernel/fork.c b/kernel/fork.c
index 11c5c8ab827c..bed8eb2ac981 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1297,7 +1297,7 @@ void __cleanup_sighand(struct sighand_struct *sighand)
 	if (atomic_dec_and_test(&sighand->count)) {
 		signalfd_cleanup(sighand);
 		/*
-		 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
+		 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
 		 * without an RCU grace period, see __lock_task_sighand().
 		 */
 		kmem_cache_free(sighand_cachep, sighand);
@@ -2069,7 +2069,7 @@ void __init proc_caches_init(void)
 {
 	sighand_cachep = kmem_cache_create("sighand_cache",
 			sizeof(struct sighand_struct), 0,
-			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
 			SLAB_NOTRACK|SLAB_ACCOUNT, sighand_ctor);
 	signal_cachep = kmem_cache_create("signal_cache",
 			sizeof(struct signal_struct), 0,
diff --git a/kernel/signal.c b/kernel/signal.c
index ff046b73ff2d..48b252238059 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1232,7 +1232,7 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
 		}
 		/*
 		 * This sighand can be already freed and even reused, but
-		 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
+		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
 		 * initializes ->siglock: this slab can't go away, it has
 		 * the same object type, ->siglock can't be reinitialized.
 		 *
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index b2a0cff2bb35..8f380e4e5cfe 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -402,7 +402,7 @@ void kasan_cache_create(struct kmem_cache *cache, size_t *size,
 	*size += sizeof(struct kasan_alloc_meta);
 
 	/* Add free meta. */
-	if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
+	if (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
 	    cache->object_size < sizeof(struct kasan_free_meta)) {
 		cache->kasan_info.free_meta_offset = *size;
 		*size += sizeof(struct kasan_free_meta);
@@ -550,7 +550,7 @@ static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
 	unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
 
 	/* RCU slabs could be legally used after free within the RCU period */
-	if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
+	if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
 		return;
 
 	kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
@@ -561,7 +561,7 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object)
 	s8 shadow_byte;
 
 	/* RCU slabs could be legally used after free within the RCU period */
-	if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
+	if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
 		return false;
 
 	shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
index 5bf191756a4a..2d5959c5f7c5 100644
--- a/mm/kmemcheck.c
+++ b/mm/kmemcheck.c
@@ -95,7 +95,7 @@ void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
 void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
 {
 	/* TODO: RCU freeing is unsupported for now; hide false positives. */
-	if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
+	if (!s->ctor && !(s->flags & SLAB_TYPESAFE_BY_RCU))
 		kmemcheck_mark_freed(object, size);
 }
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 91619fd70939..c48e9c18c8ff 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -428,7 +428,7 @@ static void anon_vma_ctor(void *data)
 void __init anon_vma_init(void)
 {
 	anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
-			0, SLAB_DESTROY_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
+			0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
 			anon_vma_ctor);
 	anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
 			SLAB_PANIC|SLAB_ACCOUNT);
@@ -479,7 +479,7 @@ struct anon_vma *page_get_anon_vma(struct page *page)
 	 * If this page is still mapped, then its anon_vma cannot have been
 	 * freed.  But if it has been unmapped, we have no security against the
 	 * anon_vma structure being freed and reused (for another anon_vma:
-	 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
+	 * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
 	 * above cannot corrupt).
 	 */
 	if (!page_mapped(page)) {
diff --git a/mm/slab.c b/mm/slab.c
index 29bc6c0dedd0..e835c652491e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1726,7 +1726,7 @@ static void slab_destroy(struct kmem_cache *cachep, struct page *page)
 
 	freelist = page->freelist;
 	slab_destroy_debugcheck(cachep, page);
-	if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
+	if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU))
 		call_rcu(&page->rcu_head, kmem_rcu_free);
 	else
 		kmem_freepages(cachep, page);
@@ -1922,7 +1922,7 @@ static bool set_objfreelist_slab_cache(struct kmem_cache *cachep,
 
 	cachep->num = 0;
 
-	if (cachep->ctor || flags & SLAB_DESTROY_BY_RCU)
+	if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU)
 		return false;
 
 	left = calculate_slab_order(cachep, size,
@@ -2028,7 +2028,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
 	if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
 						2 * sizeof(unsigned long long)))
 		flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
-	if (!(flags & SLAB_DESTROY_BY_RCU))
+	if (!(flags & SLAB_TYPESAFE_BY_RCU))
 		flags |= SLAB_POISON;
 #endif
 #endif
diff --git a/mm/slab.h b/mm/slab.h
index de6579dc362c..a379979dacc1 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -120,7 +120,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
 
 /* Legal flag mask for kmem_cache_create(), for various configurations */
 #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
-			 SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS )
+			 SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
 
 #if defined(CONFIG_DEBUG_SLAB)
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
@@ -391,7 +391,7 @@ static inline size_t slab_ksize(const struct kmem_cache *s)
 	 * back there or track user information then we can
 	 * only use the space before that information.
 	 */
-	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
+	if (s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_STORE_USER))
 		return s->inuse;
 	/*
 	 * Else we can use all the padding etc for the allocation
diff --git a/mm/slab_common.c b/mm/slab_common.c
index ae323841adb1..296413c2bbcd 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -34,7 +34,7 @@ struct kmem_cache *kmem_cache;
  * Set of flags that will prevent slab merging
  */
 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
 		SLAB_FAILSLAB | SLAB_KASAN)
 
 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
@@ -464,7 +464,7 @@ static int shutdown_cache(struct kmem_cache *s,
 	if (__kmem_cache_shutdown(s) != 0)
 		return -EBUSY;
 
-	if (s->flags & SLAB_DESTROY_BY_RCU)
+	if (s->flags & SLAB_TYPESAFE_BY_RCU)
 		*need_rcu_barrier = true;
 
 	list_move(&s->list, release);
diff --git a/mm/slob.c b/mm/slob.c
index eac04d4357ec..1bae78d71096 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -126,7 +126,7 @@ static inline void clear_slob_page_free(struct page *sp)
 
 /*
  * struct slob_rcu is inserted at the tail of allocated slob blocks, which
- * were created with a SLAB_DESTROY_BY_RCU slab. slob_rcu is used to free
+ * were created with a SLAB_TYPESAFE_BY_RCU slab. slob_rcu is used to free
  * the block using call_rcu.
  */
 struct slob_rcu {
@@ -524,7 +524,7 @@ EXPORT_SYMBOL(ksize);
 
 int __kmem_cache_create(struct kmem_cache *c, unsigned long flags)
 {
-	if (flags & SLAB_DESTROY_BY_RCU) {
+	if (flags & SLAB_TYPESAFE_BY_RCU) {
 		/* leave room for rcu footer at the end of object */
 		c->size += sizeof(struct slob_rcu);
 	}
@@ -598,7 +598,7 @@ static void kmem_rcu_free(struct rcu_head *head)
 void kmem_cache_free(struct kmem_cache *c, void *b)
 {
 	kmemleak_free_recursive(b, c->flags);
-	if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
+	if (unlikely(c->flags & SLAB_TYPESAFE_BY_RCU)) {
 		struct slob_rcu *slob_rcu;
 		slob_rcu = b + (c->size - sizeof(struct slob_rcu));
 		slob_rcu->size = c->size;
diff --git a/mm/slub.c b/mm/slub.c
index 067598a00849..c55da883d995 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1677,7 +1677,7 @@ static void rcu_free_slab(struct rcu_head *h)
 
 static void free_slab(struct kmem_cache *s, struct page *page)
 {
-	if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
+	if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
 		struct rcu_head *head;
 
 		if (need_reserve_slab_rcu) {
@@ -2953,7 +2953,7 @@ static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
 	 * slab_free_freelist_hook() could have put the items into quarantine.
 	 * If so, no need to free them.
 	 */
-	if (s->flags & SLAB_KASAN && !(s->flags & SLAB_DESTROY_BY_RCU))
+	if (s->flags & SLAB_KASAN && !(s->flags & SLAB_TYPESAFE_BY_RCU))
 		return;
 	do_slab_free(s, page, head, tail, cnt, addr);
 }
@@ -3423,7 +3423,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
 	 * the slab may touch the object after free or before allocation
 	 * then we should never poison the object itself.
 	 */
-	if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
+	if ((flags & SLAB_POISON) && !(flags & SLAB_TYPESAFE_BY_RCU) &&
 			!s->ctor)
 		s->flags |= __OBJECT_POISON;
 	else
@@ -3445,7 +3445,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
 	 */
 	s->inuse = size;
 
-	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
+	if (((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
 		s->ctor)) {
 		/*
 		 * Relocate free pointer after the object if it is not
@@ -3527,7 +3527,7 @@ static int kmem_cache_open(struct kmem_cache *s, unsigned long flags)
 	s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor);
 	s->reserved = 0;
 
-	if (need_reserve_slab_rcu && (s->flags & SLAB_DESTROY_BY_RCU))
+	if (need_reserve_slab_rcu && (s->flags & SLAB_TYPESAFE_BY_RCU))
 		s->reserved = sizeof(struct rcu_head);
 
 	if (!calculate_sizes(s, -1))
@@ -4978,7 +4978,7 @@ SLAB_ATTR_RO(cache_dma);
 
 static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
 {
-	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU));
 }
 SLAB_ATTR_RO(destroy_by_rcu);
 
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index d859a5c36e70..570ff0f03c05 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -951,7 +951,7 @@ static struct proto dccp_v4_prot = {
 	.orphan_count		= &dccp_orphan_count,
 	.max_header		= MAX_DCCP_HEADER,
 	.obj_size		= sizeof(struct dccp_sock),
-	.slab_flags		= SLAB_DESTROY_BY_RCU,
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
 	.rsk_prot		= &dccp_request_sock_ops,
 	.twsk_prot		= &dccp_timewait_sock_ops,
 	.h.hashinfo		= &dccp_hashinfo,
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index adfc790f7193..05418bb9416f 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1014,7 +1014,7 @@ static struct proto dccp_v6_prot = {
 	.orphan_count	   = &dccp_orphan_count,
 	.max_header	   = MAX_DCCP_HEADER,
 	.obj_size	   = sizeof(struct dccp6_sock),
-	.slab_flags	   = SLAB_DESTROY_BY_RCU,
+	.slab_flags	   = SLAB_TYPESAFE_BY_RCU,
 	.rsk_prot	   = &dccp6_request_sock_ops,
 	.twsk_prot	   = &dccp6_timewait_sock_ops,
 	.h.hashinfo	   = &dccp_hashinfo,
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index fe9da4fb96bf..3f622887126e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2394,7 +2394,7 @@ struct proto tcp_prot = {
 	.sysctl_rmem		= sysctl_tcp_rmem,
 	.max_header		= MAX_TCP_HEADER,
 	.obj_size		= sizeof(struct tcp_sock),
-	.slab_flags		= SLAB_DESTROY_BY_RCU,
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
 	.twsk_prot		= &tcp_timewait_sock_ops,
 	.rsk_prot		= &tcp_request_sock_ops,
 	.h.hashinfo		= &tcp_hashinfo,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 73bc8fc68acd..7c8b6ad81c66 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1907,7 +1907,7 @@ struct proto tcpv6_prot = {
 	.sysctl_rmem		= sysctl_tcp_rmem,
 	.max_header		= MAX_TCP_HEADER,
 	.obj_size		= sizeof(struct tcp6_sock),
-	.slab_flags		= SLAB_DESTROY_BY_RCU,
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
 	.twsk_prot		= &tcp6_timewait_sock_ops,
 	.rsk_prot		= &tcp6_request_sock_ops,
 	.h.hashinfo		= &tcp_hashinfo,
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 5e9296382420..b596f90340e0 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -140,7 +140,7 @@ static struct proto llc_proto = {
 	.name	  = "LLC",
 	.owner	  = THIS_MODULE,
 	.obj_size = sizeof(struct llc_sock),
-	.slab_flags = SLAB_DESTROY_BY_RCU,
+	.slab_flags = SLAB_TYPESAFE_BY_RCU,
 };
 
 /**
diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 3e821daf9dd4..ae70ba89d44f 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -506,7 +506,7 @@ static struct sock *__llc_lookup_established(struct llc_sap *sap,
 again:
 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 		if (llc_estab_match(sap, daddr, laddr, rc)) {
-			/* Extra checks required by SLAB_DESTROY_BY_RCU */
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
 				goto again;
 			if (unlikely(llc_sk(rc)->sap != sap ||
@@ -565,7 +565,7 @@ static struct sock *__llc_lookup_listener(struct llc_sap *sap,
 again:
 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 		if (llc_listener_match(sap, laddr, rc)) {
-			/* Extra checks required by SLAB_DESTROY_BY_RCU */
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
 				goto again;
 			if (unlikely(llc_sk(rc)->sap != sap ||
diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index d0e1e804ebd7..c984c4631369 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -325,7 +325,7 @@ static struct sock *llc_lookup_dgram(struct llc_sap *sap,
 again:
 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 		if (llc_dgram_match(sap, laddr, rc)) {
-			/* Extra checks required by SLAB_DESTROY_BY_RCU */
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
 				goto again;
 			if (unlikely(llc_sk(rc)->sap != sap ||
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 3a073cd9fcf4..13b7e5159660 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -895,7 +895,7 @@ static unsigned int early_drop_list(struct net *net,
 			continue;
 
 		/* kill only if still in same netns -- might have moved due to
-		 * SLAB_DESTROY_BY_RCU rules.
+		 * SLAB_TYPESAFE_BY_RCU rules.
 		 *
 		 * We steal the timer reference.  If that fails timer has
 		 * already fired or someone else deleted it. Just drop ref
@@ -1052,7 +1052,7 @@ __nf_conntrack_alloc(struct net *net,
 
 	/*
 	 * Do not use kmem_cache_zalloc(), as this cache uses
-	 * SLAB_DESTROY_BY_RCU.
+	 * SLAB_TYPESAFE_BY_RCU.
 	 */
 	ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
 	if (ct == NULL)
@@ -1097,7 +1097,7 @@ void nf_conntrack_free(struct nf_conn *ct)
 	struct net *net = nf_ct_net(ct);
 
 	/* A freed object has refcnt == 0, that's
-	 * the golden rule for SLAB_DESTROY_BY_RCU
+	 * the golden rule for SLAB_TYPESAFE_BY_RCU
 	 */
 	NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 0);
 
@@ -1863,7 +1863,7 @@ int nf_conntrack_init_start(void)
 
 	nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
 						sizeof(struct nf_conn), 0,
-						SLAB_DESTROY_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
+						SLAB_TYPESAFE_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
 	if (!nf_conntrack_cachep)
 		goto err_cachep;
 

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[willy]

On Wed, Jan 18, 2017 at 03:07:32AM -0800, Paul E. McKenney wrote:
> A group of Linux kernel hackers reported chasing a bug that resulted
> from their assumption that SLAB_DESTROY_BY_RCU provided an existence
> guarantee, that is, that no block from such a slab would be reallocated
> during an RCU read-side critical section.  Of course, that is not the
> case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
> slab of blocks.
> 
> However, there is a phrase for this, namely "type safety".  This commit
> therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
> to avoid future instances of this sort of confusion.

This is probably the ultimate in bikeshedding, but RCU is not the
thing which is providing the typesafety.  Slab is providing the
typesafety in order to help RCU.  So would a better name not be
'SLAB_TYPESAFETY_FOR_RCU', or more succinctly 'SLAB_RCU_TYPESAFE'?

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

On Wed, Jan 18, 2017 at 03:12:01AM -0800, willy@infradead.org wrote:
> On Wed, Jan 18, 2017 at 03:07:32AM -0800, Paul E. McKenney wrote:
> > A group of Linux kernel hackers reported chasing a bug that resulted
> > from their assumption that SLAB_DESTROY_BY_RCU provided an existence
> > guarantee, that is, that no block from such a slab would be reallocated
> > during an RCU read-side critical section.  Of course, that is not the
> > case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
> > slab of blocks.
> > 
> > However, there is a phrase for this, namely "type safety".  This commit
> > therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
> > to avoid future instances of this sort of confusion.
> 
> This is probably the ultimate in bikeshedding, but RCU is not the
> thing which is providing the typesafety.  Slab is providing the
> typesafety in order to help RCU.  So would a better name not be
> 'SLAB_TYPESAFETY_FOR_RCU', or more succinctly 'SLAB_RCU_TYPESAFE'?

Actually, slab is using RCU to provide type safety to those slab users
who request it.

							Thanx, Paul

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Christoph Lameter]

On Wed, 18 Jan 2017, Paul E. McKenney wrote:

> Actually, slab is using RCU to provide type safety to those slab users
> who request it.

Typesafety is a side effect. The main idea here is that the object can
still be accessed in RCU sections after another processor frees the
object. We guarantee that the object is not freed but it may be reused
for another object within the RCU period.

Can we have a name that expresses all of that properly?

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

On Wed, Jan 18, 2017 at 06:00:24PM -0600, Christoph Lameter wrote:
> On Wed, 18 Jan 2017, Paul E. McKenney wrote:
> 
> > Actually, slab is using RCU to provide type safety to those slab users
> > who request it.
> 
> Typesafety is a side effect. The main idea here is that the object can
> still be accessed in RCU sections after another processor frees the
> object. We guarantee that the object is not freed but it may be reused
> for another object within the RCU period.
> 
> Can we have a name that expresses all of that properly?

But of course!!!  "Type safety".  http://wiki.c2.com/?TypeSafe

							Thanx, Paul

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Christoph Lameter]

On Sun, 22 Jan 2017, Paul E. McKenney wrote:

> On Wed, Jan 18, 2017 at 06:00:24PM -0600, Christoph Lameter wrote:
> > On Wed, 18 Jan 2017, Paul E. McKenney wrote:
> >
> > > Actually, slab is using RCU to provide type safety to those slab users
> > > who request it.
> >
> > Typesafety is a side effect. The main idea here is that the object can
> > still be accessed in RCU sections after another processor frees the
> > object. We guarantee that the object is not freed but it may be reused
> > for another object within the RCU period.
> >
> > Can we have a name that expresses all of that properly?
>
> But of course!!!  "Type safety".  http://wiki.c2.com/?TypeSafe

Well that does not convey the idea that RCU is involved here.

SLAB_DESTROY_RCU_TYPESAFE

?

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Eric Dumazet]

On Wed, 2017-01-25 at 10:45 -0600, Christoph Lameter wrote:
> On Sun, 22 Jan 2017, Paul E. McKenney wrote:
> 
> > On Wed, Jan 18, 2017 at 06:00:24PM -0600, Christoph Lameter wrote:
> > > On Wed, 18 Jan 2017, Paul E. McKenney wrote:
> > >
> > > > Actually, slab is using RCU to provide type safety to those slab users
> > > > who request it.
> > >
> > > Typesafety is a side effect. The main idea here is that the object can
> > > still be accessed in RCU sections after another processor frees the
> > > object. We guarantee that the object is not freed but it may be reused
> > > for another object within the RCU period.
> > >
> > > Can we have a name that expresses all of that properly?
> >
> > But of course!!!  "Type safety".  http://wiki.c2.com/?TypeSafe
> 
> Well that does not convey the idea that RCU is involved here.
> 
> SLAB_DESTROY_RCU_TYPESAFE

Not clear why we need to change this very fine name ?

SLAB_DESTROY_BY_RCU was only used by few of us, we know damn well what
it means.

Consider we wont be able to change it in various web pages / archives /
changelogs.

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

On Wed, Jan 25, 2017 at 09:04:47AM -0800, Eric Dumazet wrote:
> On Wed, 2017-01-25 at 10:45 -0600, Christoph Lameter wrote:
> > On Sun, 22 Jan 2017, Paul E. McKenney wrote:
> > 
> > > On Wed, Jan 18, 2017 at 06:00:24PM -0600, Christoph Lameter wrote:
> > > > On Wed, 18 Jan 2017, Paul E. McKenney wrote:
> > > >
> > > > > Actually, slab is using RCU to provide type safety to those slab users
> > > > > who request it.
> > > >
> > > > Typesafety is a side effect. The main idea here is that the object can
> > > > still be accessed in RCU sections after another processor frees the
> > > > object. We guarantee that the object is not freed but it may be reused
> > > > for another object within the RCU period.
> > > >
> > > > Can we have a name that expresses all of that properly?
> > >
> > > But of course!!!  "Type safety".  http://wiki.c2.com/?TypeSafe
> > 
> > Well that does not convey the idea that RCU is involved here.
> > 
> > SLAB_DESTROY_RCU_TYPESAFE
> 
> Not clear why we need to change this very fine name ?
> 
> SLAB_DESTROY_BY_RCU was only used by few of us, we know damn well what
> it means.
> 
> Consider we wont be able to change it in various web pages / archives /
> changelogs.

The reason I proposed this change is that I ran into some people last
week who had burned some months learning that this very fine flag
provides only type safety, not identity safety.

Other proposals?

							Thanx, Paul

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Johannes Weiner]

On Wed, Jan 18, 2017 at 03:07:32AM -0800, Paul E. McKenney wrote:
> A group of Linux kernel hackers reported chasing a bug that resulted
> from their assumption that SLAB_DESTROY_BY_RCU provided an existence
> guarantee, that is, that no block from such a slab would be reallocated
> during an RCU read-side critical section.  Of course, that is not the
> case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
> slab of blocks.
> 
> However, there is a phrase for this, namely "type safety".  This commit
> therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
> to avoid future instances of this sort of confusion.
> 
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

This has come up in the past, and it always proved hard to agree on a
better name for it. But I like SLAB_TYPESAFE_BY_RCU the best out of
all proposals, and it's much more poignant than the current name.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Vlastimil Babka]

On 01/25/2017 09:25 PM, Johannes Weiner wrote:
> On Wed, Jan 18, 2017 at 03:07:32AM -0800, Paul E. McKenney wrote:
>> A group of Linux kernel hackers reported chasing a bug that resulted
>> from their assumption that SLAB_DESTROY_BY_RCU provided an existence
>> guarantee, that is, that no block from such a slab would be reallocated
>> during an RCU read-side critical section.  Of course, that is not the
>> case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
>> slab of blocks.
>>
>> However, there is a phrase for this, namely "type safety".  This commit
>> therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
>> to avoid future instances of this sort of confusion.
>>
>> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> This has come up in the past, and it always proved hard to agree on a
> better name for it. But I like SLAB_TYPESAFE_BY_RCU the best out of
> all proposals, and it's much more poignant than the current name.

Heh, until I've seen this thread I had the same wrong assumption about the flag, 
so it suprised me. Good thing I didn't have a chance to use it wrongly so far :)

"Type safety" in this context seems quite counter-intuitive for me, as I've only 
heard it to describe programming languages. But that's fine when the name sounds 
so exotic that one has to look up what it does. Much safer than when the meaning 
seems obvious, but in fact it's misleading.

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

On Wed, Jan 25, 2017 at 10:26:08PM +0100, Vlastimil Babka wrote:
> On 01/25/2017 09:25 PM, Johannes Weiner wrote:
> >On Wed, Jan 18, 2017 at 03:07:32AM -0800, Paul E. McKenney wrote:
> >>A group of Linux kernel hackers reported chasing a bug that resulted
> >>from their assumption that SLAB_DESTROY_BY_RCU provided an existence
> >>guarantee, that is, that no block from such a slab would be reallocated
> >>during an RCU read-side critical section.  Of course, that is not the
> >>case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
> >>slab of blocks.
> >>
> >>However, there is a phrase for this, namely "type safety".  This commit
> >>therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
> >>to avoid future instances of this sort of confusion.
> >>
> >>Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> >
> >This has come up in the past, and it always proved hard to agree on a
> >better name for it. But I like SLAB_TYPESAFE_BY_RCU the best out of
> >all proposals, and it's much more poignant than the current name.
> 
> Heh, until I've seen this thread I had the same wrong assumption
> about the flag, so it suprised me. Good thing I didn't have a chance
> to use it wrongly so far :)
> 
> "Type safety" in this context seems quite counter-intuitive for me,
> as I've only heard it to describe programming languages. But that's
> fine when the name sounds so exotic that one has to look up what it
> does. Much safer than when the meaning seems obvious, but in fact
> it's misleading.
> 
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> 
> >Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Thank you both!  I have added these, as well as a Not-acked-by
for Eric.  ;-)

							Thanx, Paul

> >--
> >To unsubscribe, send a message with 'unsubscribe linux-mm' in
> >the body to majordomo@kvack.org.  For more info on Linux MM,
> >see: http://www.linux-mm.org/ .
> >Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> >
> 

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Eric Dumazet]

On Wed, 2017-01-25 at 12:07 -0800, Paul E. McKenney wrote:
> On Wed, Jan 25, 2017 at 09:04:47AM -0800, Eric Dumazet wrote:

> > 
> > Not clear why we need to change this very fine name ?
> > 
> > SLAB_DESTROY_BY_RCU was only used by few of us, we know damn well what
> > it means.
> > 
> > Consider we wont be able to change it in various web pages / archives /
> > changelogs.
> 
> The reason I proposed this change is that I ran into some people last
> week who had burned some months learning that this very fine flag
> provides only type safety, not identity safety.
> 
> Other proposals?

Bung hunting requires scrapping git log, in particular in areas touching
RCU (not exactly trivial stuff :) :) :) )

git log | grep SLAB_DESTROY_BY_RCU 

A Google search on SLAB_DESTROY_BY_RCU finds ~4600 results.

If we rename SLAB_DESTROY_BY_RCU by XXXXXXXX, someone trying to see
prior patches or articles about XXXXXXXX mistakes will find nothing.

So please leave comments giving the old name ( SLAB_DESTROY_BY_RCU ) and
save time for future hackers.

Thanks.

Re: [PATCH RFC] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

On Wed, Jan 25, 2017 at 02:46:17PM -0800, Eric Dumazet wrote:
> On Wed, 2017-01-25 at 12:07 -0800, Paul E. McKenney wrote:
> > On Wed, Jan 25, 2017 at 09:04:47AM -0800, Eric Dumazet wrote:
> 
> > > 
> > > Not clear why we need to change this very fine name ?
> > > 
> > > SLAB_DESTROY_BY_RCU was only used by few of us, we know damn well what
> > > it means.
> > > 
> > > Consider we wont be able to change it in various web pages / archives /
> > > changelogs.
> > 
> > The reason I proposed this change is that I ran into some people last
> > week who had burned some months learning that this very fine flag
> > provides only type safety, not identity safety.
> > 
> > Other proposals?
> 
> Bung hunting requires scrapping git log, in particular in areas touching
> RCU (not exactly trivial stuff :) :) :) )
> 
> git log | grep SLAB_DESTROY_BY_RCU 
> 
> A Google search on SLAB_DESTROY_BY_RCU finds ~4600 results.
> 
> If we rename SLAB_DESTROY_BY_RCU by XXXXXXXX, someone trying to see
> prior patches or articles about XXXXXXXX mistakes will find nothing.
> 
> So please leave comments giving the old name ( SLAB_DESTROY_BY_RCU ) and
> save time for future hackers.

Good point!  How about the following diff against the old patch?

------------------------------------------------------------------------

diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 12374fa4cff1..91c912e86915 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -925,7 +925,8 @@ d.	Do you need RCU grace periods to complete even in the face
 
 e.	Is your workload too update-intensive for normal use of
 	RCU, but inappropriate for other synchronization mechanisms?
-	If so, consider SLAB_TYPESAFE_BY_RCU.  But please be careful!
+	If so, consider SLAB_TYPESAFE_BY_RCU (which was originally
+	named SLAB_DESTROY_BY_RCU).  But please be careful!
 
 f.	Do you need read-side critical sections that are respected
 	even though they are in the middle of the idle loop, during
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 708d5b1dc439..f57b6c7cd530 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -61,6 +61,8 @@
  *
  * rcu_read_lock before reading the address, then rcu_read_unlock after
  * taking the spinlock within the structure expected at that address.
+ *
+ * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
  */
 #define SLAB_TYPESAFE_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
 #define SLAB_MEM_SPREAD		0x00100000UL	/* Spread some memory over cpuset */

------------------------------------------------------------------------

Any other "tombstone" comments needed?

The full patch is shown below for completeness.

							Thanx, Paul

------------------------------------------------------------------------

commit 55f619e5c322171698f0d5aecf5009391ac7e2db
Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date:   Wed Jan 18 02:53:44 2017 -0800

    mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU
    
    A group of Linux kernel hackers reported chasing a bug that resulted
    from their assumption that SLAB_DESTROY_BY_RCU provided an existence
    guarantee, that is, that no block from such a slab would be reallocated
    during an RCU read-side critical section.  Of course, that is not the
    case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
    slab of blocks.
    
    However, there is a phrase for this, namely "type safety".  This commit
    therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order
    to avoid future instances of this sort of confusion.
    
    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: <linux-mm@kvack.org>
    Acked-by: Johannes Weiner <hannes@cmpxchg.org>
    Acked-by: Vlastimil Babka <vbabka@suse.cz>
    [ paulmck: Add "tombstone" comments as requested by Eric Dumazet. ]

diff --git a/Documentation/RCU/00-INDEX b/Documentation/RCU/00-INDEX
index f773a264ae02..1672573b037a 100644
--- a/Documentation/RCU/00-INDEX
+++ b/Documentation/RCU/00-INDEX
@@ -17,7 +17,7 @@ rcu_dereference.txt
 rcubarrier.txt
 	- RCU and Unloadable Modules
 rculist_nulls.txt
-	- RCU list primitives for use with SLAB_DESTROY_BY_RCU
+	- RCU list primitives for use with SLAB_TYPESAFE_BY_RCU
 rcuref.txt
 	- Reference-count design for elements of lists/arrays protected by RCU
 rcu.txt
diff --git a/Documentation/RCU/rculist_nulls.txt b/Documentation/RCU/rculist_nulls.txt
index 18f9651ff23d..8151f0195f76 100644
--- a/Documentation/RCU/rculist_nulls.txt
+++ b/Documentation/RCU/rculist_nulls.txt
@@ -1,5 +1,5 @@
 Using hlist_nulls to protect read-mostly linked lists and
-objects using SLAB_DESTROY_BY_RCU allocations.
+objects using SLAB_TYPESAFE_BY_RCU allocations.
 
 Please read the basics in Documentation/RCU/listRCU.txt
 
@@ -7,7 +7,7 @@ Using special makers (called 'nulls') is a convenient way
 to solve following problem :
 
 A typical RCU linked list managing objects which are
-allocated with SLAB_DESTROY_BY_RCU kmem_cache can
+allocated with SLAB_TYPESAFE_BY_RCU kmem_cache can
 use following algos :
 
 1) Lookup algo
@@ -96,7 +96,7 @@ unlock_chain(); // typically a spin_unlock()
 3) Remove algo
 --------------
 Nothing special here, we can use a standard RCU hlist deletion.
-But thanks to SLAB_DESTROY_BY_RCU, beware a deleted object can be reused
+But thanks to SLAB_TYPESAFE_BY_RCU, beware a deleted object can be reused
 very very fast (before the end of RCU grace period)
 
 if (put_last_reference_on(obj) {
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 5cbd8b2395b8..91c912e86915 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -925,7 +925,8 @@ d.	Do you need RCU grace periods to complete even in the face
 
 e.	Is your workload too update-intensive for normal use of
 	RCU, but inappropriate for other synchronization mechanisms?
-	If so, consider SLAB_DESTROY_BY_RCU.  But please be careful!
+	If so, consider SLAB_TYPESAFE_BY_RCU (which was originally
+	named SLAB_DESTROY_BY_RCU).  But please be careful!
 
 f.	Do you need read-side critical sections that are respected
 	even though they are in the middle of the idle loop, during
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3dd7fc662859..3871ca092aa6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4541,7 +4541,7 @@ i915_gem_load_init(struct drm_device *dev)
 	dev_priv->requests = KMEM_CACHE(drm_i915_gem_request,
 					SLAB_HWCACHE_ALIGN |
 					SLAB_RECLAIM_ACCOUNT |
-					SLAB_DESTROY_BY_RCU);
+					SLAB_TYPESAFE_BY_RCU);
 	if (!dev_priv->requests)
 		goto err_vmas;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
index d229f47d1028..50d1075c9dab 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.h
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -504,7 +504,7 @@ static inline struct drm_i915_gem_request *
 __i915_gem_active_get_rcu(const struct i915_gem_active *active)
 {
 	/* Performing a lockless retrieval of the active request is super
-	 * tricky. SLAB_DESTROY_BY_RCU merely guarantees that the backing
+	 * tricky. SLAB_TYPESAFE_BY_RCU merely guarantees that the backing
 	 * slab of request objects will not be freed whilst we hold the
 	 * RCU read lock. It does not guarantee that the request itself
 	 * will not be freed and then *reused*. Viz,
diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
index 12647af5a336..e7fb47e84a93 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c
@@ -1071,7 +1071,7 @@ int ldlm_init(void)
 	ldlm_lock_slab = kmem_cache_create("ldlm_locks",
 					   sizeof(struct ldlm_lock), 0,
 					   SLAB_HWCACHE_ALIGN |
-					   SLAB_DESTROY_BY_RCU, NULL);
+					   SLAB_TYPESAFE_BY_RCU, NULL);
 	if (!ldlm_lock_slab) {
 		kmem_cache_destroy(ldlm_resource_slab);
 		return -ENOMEM;
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index a097048ed1a3..8d0cbcc4c877 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2340,7 +2340,7 @@ static int jbd2_journal_init_journal_head_cache(void)
 	jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
 				sizeof(struct journal_head),
 				0,		/* offset */
-				SLAB_TEMPORARY | SLAB_DESTROY_BY_RCU,
+				SLAB_TEMPORARY | SLAB_TYPESAFE_BY_RCU,
 				NULL);		/* ctor */
 	retval = 0;
 	if (!jbd2_journal_head_cache) {
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 270221fcef42..7e3d71109f51 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -38,7 +38,7 @@ void signalfd_cleanup(struct sighand_struct *sighand)
 	/*
 	 * The lockless check can race with remove_wait_queue() in progress,
 	 * but in this case its caller should run under rcu_read_lock() and
-	 * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return.
+	 * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return.
 	 */
 	if (likely(!waitqueue_active(wqh)))
 		return;
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index d51a7d23c358..236fc0dbef39 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -229,7 +229,7 @@ static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)
  *
  * Function returns NULL if no refcount could be obtained, or the fence.
  * This function handles acquiring a reference to a fence that may be
- * reallocated within the RCU grace period (such as with SLAB_DESTROY_BY_RCU),
+ * reallocated within the RCU grace period (such as with SLAB_TYPESAFE_BY_RCU),
  * so long as the caller is using RCU on the pointer to the fence.
  *
  * An alternative mechanism is to employ a seqlock to protect a bunch of
@@ -257,7 +257,7 @@ dma_fence_get_rcu_safe(struct dma_fence * __rcu *fencep)
 		 * have successfully acquire a reference to it. If it no
 		 * longer matches, we are holding a reference to some other
 		 * reallocated pointer. This is possible if the allocator
-		 * is using a freelist like SLAB_DESTROY_BY_RCU where the
+		 * is using a freelist like SLAB_TYPESAFE_BY_RCU where the
 		 * fence remains valid for the RCU grace period, but it
 		 * may be reallocated. When using such allocators, we are
 		 * responsible for ensuring the reference we get is to
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 084b12bad198..f57b6c7cd530 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -28,7 +28,7 @@
 #define SLAB_STORE_USER		0x00010000UL	/* DEBUG: Store the last owner for bug hunting */
 #define SLAB_PANIC		0x00040000UL	/* Panic if kmem_cache_create() fails */
 /*
- * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
+ * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
  *
  * This delays freeing the SLAB page by a grace period, it does _NOT_
  * delay object freeing. This means that if you do kmem_cache_free()
@@ -61,8 +61,10 @@
  *
  * rcu_read_lock before reading the address, then rcu_read_unlock after
  * taking the spinlock within the structure expected at that address.
+ *
+ * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
  */
-#define SLAB_DESTROY_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
+#define SLAB_TYPESAFE_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
 #define SLAB_MEM_SPREAD		0x00100000UL	/* Spread some memory over cpuset */
 #define SLAB_TRACE		0x00200000UL	/* Trace allocations and frees */
 
diff --git a/include/net/sock.h b/include/net/sock.h
index f0e867f58722..981b0cad8358 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -989,7 +989,7 @@ struct raw_hashinfo;
 struct module;
 
 /*
- * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
+ * caches using SLAB_TYPESAFE_BY_RCU should let .next pointer from nulls nodes
  * un-modified. Special care is taken when initializing object to zero.
  */
 static inline void sk_prot_clear_nulls(struct sock *sk, int size)
diff --git a/kernel/fork.c b/kernel/fork.c
index 11c5c8ab827c..bed8eb2ac981 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1297,7 +1297,7 @@ void __cleanup_sighand(struct sighand_struct *sighand)
 	if (atomic_dec_and_test(&sighand->count)) {
 		signalfd_cleanup(sighand);
 		/*
-		 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
+		 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
 		 * without an RCU grace period, see __lock_task_sighand().
 		 */
 		kmem_cache_free(sighand_cachep, sighand);
@@ -2069,7 +2069,7 @@ void __init proc_caches_init(void)
 {
 	sighand_cachep = kmem_cache_create("sighand_cache",
 			sizeof(struct sighand_struct), 0,
-			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
 			SLAB_NOTRACK|SLAB_ACCOUNT, sighand_ctor);
 	signal_cachep = kmem_cache_create("signal_cache",
 			sizeof(struct signal_struct), 0,
diff --git a/kernel/signal.c b/kernel/signal.c
index ff046b73ff2d..48b252238059 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1232,7 +1232,7 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
 		}
 		/*
 		 * This sighand can be already freed and even reused, but
-		 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
+		 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
 		 * initializes ->siglock: this slab can't go away, it has
 		 * the same object type, ->siglock can't be reinitialized.
 		 *
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index b2a0cff2bb35..8f380e4e5cfe 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -402,7 +402,7 @@ void kasan_cache_create(struct kmem_cache *cache, size_t *size,
 	*size += sizeof(struct kasan_alloc_meta);
 
 	/* Add free meta. */
-	if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
+	if (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
 	    cache->object_size < sizeof(struct kasan_free_meta)) {
 		cache->kasan_info.free_meta_offset = *size;
 		*size += sizeof(struct kasan_free_meta);
@@ -550,7 +550,7 @@ static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
 	unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
 
 	/* RCU slabs could be legally used after free within the RCU period */
-	if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
+	if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
 		return;
 
 	kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
@@ -561,7 +561,7 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object)
 	s8 shadow_byte;
 
 	/* RCU slabs could be legally used after free within the RCU period */
-	if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
+	if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
 		return false;
 
 	shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
index 5bf191756a4a..2d5959c5f7c5 100644
--- a/mm/kmemcheck.c
+++ b/mm/kmemcheck.c
@@ -95,7 +95,7 @@ void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
 void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
 {
 	/* TODO: RCU freeing is unsupported for now; hide false positives. */
-	if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
+	if (!s->ctor && !(s->flags & SLAB_TYPESAFE_BY_RCU))
 		kmemcheck_mark_freed(object, size);
 }
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 91619fd70939..c48e9c18c8ff 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -428,7 +428,7 @@ static void anon_vma_ctor(void *data)
 void __init anon_vma_init(void)
 {
 	anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
-			0, SLAB_DESTROY_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
+			0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
 			anon_vma_ctor);
 	anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
 			SLAB_PANIC|SLAB_ACCOUNT);
@@ -479,7 +479,7 @@ struct anon_vma *page_get_anon_vma(struct page *page)
 	 * If this page is still mapped, then its anon_vma cannot have been
 	 * freed.  But if it has been unmapped, we have no security against the
 	 * anon_vma structure being freed and reused (for another anon_vma:
-	 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
+	 * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
 	 * above cannot corrupt).
 	 */
 	if (!page_mapped(page)) {
diff --git a/mm/slab.c b/mm/slab.c
index 29bc6c0dedd0..e835c652491e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1726,7 +1726,7 @@ static void slab_destroy(struct kmem_cache *cachep, struct page *page)
 
 	freelist = page->freelist;
 	slab_destroy_debugcheck(cachep, page);
-	if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
+	if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU))
 		call_rcu(&page->rcu_head, kmem_rcu_free);
 	else
 		kmem_freepages(cachep, page);
@@ -1922,7 +1922,7 @@ static bool set_objfreelist_slab_cache(struct kmem_cache *cachep,
 
 	cachep->num = 0;
 
-	if (cachep->ctor || flags & SLAB_DESTROY_BY_RCU)
+	if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU)
 		return false;
 
 	left = calculate_slab_order(cachep, size,
@@ -2028,7 +2028,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
 	if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
 						2 * sizeof(unsigned long long)))
 		flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
-	if (!(flags & SLAB_DESTROY_BY_RCU))
+	if (!(flags & SLAB_TYPESAFE_BY_RCU))
 		flags |= SLAB_POISON;
 #endif
 #endif
diff --git a/mm/slab.h b/mm/slab.h
index de6579dc362c..a379979dacc1 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -120,7 +120,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
 
 /* Legal flag mask for kmem_cache_create(), for various configurations */
 #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
-			 SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS )
+			 SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
 
 #if defined(CONFIG_DEBUG_SLAB)
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
@@ -391,7 +391,7 @@ static inline size_t slab_ksize(const struct kmem_cache *s)
 	 * back there or track user information then we can
 	 * only use the space before that information.
 	 */
-	if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
+	if (s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_STORE_USER))
 		return s->inuse;
 	/*
 	 * Else we can use all the padding etc for the allocation
diff --git a/mm/slab_common.c b/mm/slab_common.c
index ae323841adb1..296413c2bbcd 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -34,7 +34,7 @@ struct kmem_cache *kmem_cache;
  * Set of flags that will prevent slab merging
  */
 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
 		SLAB_FAILSLAB | SLAB_KASAN)
 
 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
@@ -464,7 +464,7 @@ static int shutdown_cache(struct kmem_cache *s,
 	if (__kmem_cache_shutdown(s) != 0)
 		return -EBUSY;
 
-	if (s->flags & SLAB_DESTROY_BY_RCU)
+	if (s->flags & SLAB_TYPESAFE_BY_RCU)
 		*need_rcu_barrier = true;
 
 	list_move(&s->list, release);
diff --git a/mm/slob.c b/mm/slob.c
index eac04d4357ec..1bae78d71096 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -126,7 +126,7 @@ static inline void clear_slob_page_free(struct page *sp)
 
 /*
  * struct slob_rcu is inserted at the tail of allocated slob blocks, which
- * were created with a SLAB_DESTROY_BY_RCU slab. slob_rcu is used to free
+ * were created with a SLAB_TYPESAFE_BY_RCU slab. slob_rcu is used to free
  * the block using call_rcu.
  */
 struct slob_rcu {
@@ -524,7 +524,7 @@ EXPORT_SYMBOL(ksize);
 
 int __kmem_cache_create(struct kmem_cache *c, unsigned long flags)
 {
-	if (flags & SLAB_DESTROY_BY_RCU) {
+	if (flags & SLAB_TYPESAFE_BY_RCU) {
 		/* leave room for rcu footer at the end of object */
 		c->size += sizeof(struct slob_rcu);
 	}
@@ -598,7 +598,7 @@ static void kmem_rcu_free(struct rcu_head *head)
 void kmem_cache_free(struct kmem_cache *c, void *b)
 {
 	kmemleak_free_recursive(b, c->flags);
-	if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
+	if (unlikely(c->flags & SLAB_TYPESAFE_BY_RCU)) {
 		struct slob_rcu *slob_rcu;
 		slob_rcu = b + (c->size - sizeof(struct slob_rcu));
 		slob_rcu->size = c->size;
diff --git a/mm/slub.c b/mm/slub.c
index 067598a00849..c55da883d995 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1677,7 +1677,7 @@ static void rcu_free_slab(struct rcu_head *h)
 
 static void free_slab(struct kmem_cache *s, struct page *page)
 {
-	if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
+	if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
 		struct rcu_head *head;
 
 		if (need_reserve_slab_rcu) {
@@ -2953,7 +2953,7 @@ static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
 	 * slab_free_freelist_hook() could have put the items into quarantine.
 	 * If so, no need to free them.
 	 */
-	if (s->flags & SLAB_KASAN && !(s->flags & SLAB_DESTROY_BY_RCU))
+	if (s->flags & SLAB_KASAN && !(s->flags & SLAB_TYPESAFE_BY_RCU))
 		return;
 	do_slab_free(s, page, head, tail, cnt, addr);
 }
@@ -3423,7 +3423,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
 	 * the slab may touch the object after free or before allocation
 	 * then we should never poison the object itself.
 	 */
-	if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
+	if ((flags & SLAB_POISON) && !(flags & SLAB_TYPESAFE_BY_RCU) &&
 			!s->ctor)
 		s->flags |= __OBJECT_POISON;
 	else
@@ -3445,7 +3445,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
 	 */
 	s->inuse = size;
 
-	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
+	if (((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
 		s->ctor)) {
 		/*
 		 * Relocate free pointer after the object if it is not
@@ -3527,7 +3527,7 @@ static int kmem_cache_open(struct kmem_cache *s, unsigned long flags)
 	s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor);
 	s->reserved = 0;
 
-	if (need_reserve_slab_rcu && (s->flags & SLAB_DESTROY_BY_RCU))
+	if (need_reserve_slab_rcu && (s->flags & SLAB_TYPESAFE_BY_RCU))
 		s->reserved = sizeof(struct rcu_head);
 
 	if (!calculate_sizes(s, -1))
@@ -4978,7 +4978,7 @@ SLAB_ATTR_RO(cache_dma);
 
 static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
 {
-	return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
+	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU));
 }
 SLAB_ATTR_RO(destroy_by_rcu);
 
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index d859a5c36e70..570ff0f03c05 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -951,7 +951,7 @@ static struct proto dccp_v4_prot = {
 	.orphan_count		= &dccp_orphan_count,
 	.max_header		= MAX_DCCP_HEADER,
 	.obj_size		= sizeof(struct dccp_sock),
-	.slab_flags		= SLAB_DESTROY_BY_RCU,
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
 	.rsk_prot		= &dccp_request_sock_ops,
 	.twsk_prot		= &dccp_timewait_sock_ops,
 	.h.hashinfo		= &dccp_hashinfo,
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index adfc790f7193..05418bb9416f 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1014,7 +1014,7 @@ static struct proto dccp_v6_prot = {
 	.orphan_count	   = &dccp_orphan_count,
 	.max_header	   = MAX_DCCP_HEADER,
 	.obj_size	   = sizeof(struct dccp6_sock),
-	.slab_flags	   = SLAB_DESTROY_BY_RCU,
+	.slab_flags	   = SLAB_TYPESAFE_BY_RCU,
 	.rsk_prot	   = &dccp6_request_sock_ops,
 	.twsk_prot	   = &dccp6_timewait_sock_ops,
 	.h.hashinfo	   = &dccp_hashinfo,
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index fe9da4fb96bf..3f622887126e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2394,7 +2394,7 @@ struct proto tcp_prot = {
 	.sysctl_rmem		= sysctl_tcp_rmem,
 	.max_header		= MAX_TCP_HEADER,
 	.obj_size		= sizeof(struct tcp_sock),
-	.slab_flags		= SLAB_DESTROY_BY_RCU,
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
 	.twsk_prot		= &tcp_timewait_sock_ops,
 	.rsk_prot		= &tcp_request_sock_ops,
 	.h.hashinfo		= &tcp_hashinfo,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 73bc8fc68acd..7c8b6ad81c66 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1907,7 +1907,7 @@ struct proto tcpv6_prot = {
 	.sysctl_rmem		= sysctl_tcp_rmem,
 	.max_header		= MAX_TCP_HEADER,
 	.obj_size		= sizeof(struct tcp6_sock),
-	.slab_flags		= SLAB_DESTROY_BY_RCU,
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
 	.twsk_prot		= &tcp6_timewait_sock_ops,
 	.rsk_prot		= &tcp6_request_sock_ops,
 	.h.hashinfo		= &tcp_hashinfo,
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 5e9296382420..b596f90340e0 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -140,7 +140,7 @@ static struct proto llc_proto = {
 	.name	  = "LLC",
 	.owner	  = THIS_MODULE,
 	.obj_size = sizeof(struct llc_sock),
-	.slab_flags = SLAB_DESTROY_BY_RCU,
+	.slab_flags = SLAB_TYPESAFE_BY_RCU,
 };
 
 /**
diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 3e821daf9dd4..ae70ba89d44f 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -506,7 +506,7 @@ static struct sock *__llc_lookup_established(struct llc_sap *sap,
 again:
 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 		if (llc_estab_match(sap, daddr, laddr, rc)) {
-			/* Extra checks required by SLAB_DESTROY_BY_RCU */
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
 				goto again;
 			if (unlikely(llc_sk(rc)->sap != sap ||
@@ -565,7 +565,7 @@ static struct sock *__llc_lookup_listener(struct llc_sap *sap,
 again:
 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 		if (llc_listener_match(sap, laddr, rc)) {
-			/* Extra checks required by SLAB_DESTROY_BY_RCU */
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
 				goto again;
 			if (unlikely(llc_sk(rc)->sap != sap ||
diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index d0e1e804ebd7..c984c4631369 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -325,7 +325,7 @@ static struct sock *llc_lookup_dgram(struct llc_sap *sap,
 again:
 	sk_nulls_for_each_rcu(rc, node, laddr_hb) {
 		if (llc_dgram_match(sap, laddr, rc)) {
-			/* Extra checks required by SLAB_DESTROY_BY_RCU */
+			/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
 			if (unlikely(!atomic_inc_not_zero(&rc->sk_refcnt)))
 				goto again;
 			if (unlikely(llc_sk(rc)->sap != sap ||
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 3a073cd9fcf4..13b7e5159660 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -895,7 +895,7 @@ static unsigned int early_drop_list(struct net *net,
 			continue;
 
 		/* kill only if still in same netns -- might have moved due to
-		 * SLAB_DESTROY_BY_RCU rules.
+		 * SLAB_TYPESAFE_BY_RCU rules.
 		 *
 		 * We steal the timer reference.  If that fails timer has
 		 * already fired or someone else deleted it. Just drop ref
@@ -1052,7 +1052,7 @@ __nf_conntrack_alloc(struct net *net,
 
 	/*
 	 * Do not use kmem_cache_zalloc(), as this cache uses
-	 * SLAB_DESTROY_BY_RCU.
+	 * SLAB_TYPESAFE_BY_RCU.
 	 */
 	ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
 	if (ct == NULL)
@@ -1097,7 +1097,7 @@ void nf_conntrack_free(struct nf_conn *ct)
 	struct net *net = nf_ct_net(ct);
 
 	/* A freed object has refcnt == 0, that's
-	 * the golden rule for SLAB_DESTROY_BY_RCU
+	 * the golden rule for SLAB_TYPESAFE_BY_RCU
 	 */
 	NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 0);
 
@@ -1863,7 +1863,7 @@ int nf_conntrack_init_start(void)
 
 	nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
 						sizeof(struct nf_conn), 0,
-						SLAB_DESTROY_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
+						SLAB_TYPESAFE_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
 	if (!nf_conntrack_cachep)
 		goto err_cachep;