X-Git-Url: http://git.monstr.eu/?a=blobdiff_plain;f=mm%2Fslub.c;h=3d2025f7163b295c45c2b26a8c5260414b2fc238;hb=2c3ef25c4a60cc18cf3f05a74c78220748f25684;hp=e9d582eee7d7514ba2aa5571bd77d5c2cd3b509e;hpb=75c8ff281d7a6faa650bb9b32052f3ee1b5f8e83;p=linux-2.6-microblaze.git

diff --git a/mm/slub.c b/mm/slub.c
index e9d582eee7d7..3d2025f7163b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -46,13 +46,21 @@
 /*
  * Lock order:
  *   1. slab_mutex (Global Mutex)
- *   2. node->list_lock
- *   3. slab_lock(page) (Only on some arches and for debugging)
+ *   2. node->list_lock (Spinlock)
+ *   3. kmem_cache->cpu_slab->lock (Local lock)
+ *   4. slab_lock(page) (Only on some arches or for debugging)
+ *   5. object_map_lock (Only for debugging)
  *
  *   slab_mutex
  *
  *   The role of the slab_mutex is to protect the list of all the slabs
  *   and to synchronize major metadata changes to slab cache structures.
+ *   Also synchronizes memory hotplug callbacks.
+ *
+ *   slab_lock
+ *
+ *   The slab_lock is a wrapper around the page lock, thus it is a bit
+ *   spinlock.
  *
  *   The slab_lock is only used for debugging and on arches that do not
  *   have the ability to do a cmpxchg_double. It only protects:
@@ -61,6 +69,8 @@
  *	C. page->objects	-> Number of objects in page
  *	D. page->frozen		-> frozen state
  *
+ *   Frozen slabs
+ *
  *   If a slab is frozen then it is exempt from list management. It is not
  *   on any list except per cpu partial list. The processor that froze the
  *   slab is the one who can perform list operations on the page. Other
@@ -68,6 +78,8 @@
  *   froze the slab is the only one that can retrieve the objects from the
  *   page's freelist.
  *
+ *   list_lock
+ *
  *   The list_lock protects the partial and full list on each node and
  *   the partial slab counter. If taken then no new slabs may be added or
  *   removed from the lists nor make the number of partial slabs be modified.
@@ -79,10 +91,36 @@
  *   slabs, operations can continue without any centralized lock. F.e.
  *   allocating a long series of objects that fill up slabs does not require
  *   the list lock.
- *   Interrupts are disabled during allocation and deallocation in order to
- *   make the slab allocator safe to use in the context of an irq. In addition
- *   interrupts are disabled to ensure that the processor does not change
- *   while handling per_cpu slabs, due to kernel preemption.
+ *
+ *   cpu_slab->lock local lock
+ *
+ *   This locks protect slowpath manipulation of all kmem_cache_cpu fields
+ *   except the stat counters. This is a percpu structure manipulated only by
+ *   the local cpu, so the lock protects against being preempted or interrupted
+ *   by an irq. Fast path operations rely on lockless operations instead.
+ *   On PREEMPT_RT, the local lock does not actually disable irqs (and thus
+ *   prevent the lockless operations), so fastpath operations also need to take
+ *   the lock and are no longer lockless.
+ *
+ *   lockless fastpaths
+ *
+ *   The fast path allocation (slab_alloc_node()) and freeing (do_slab_free())
+ *   are fully lockless when satisfied from the percpu slab (and when
+ *   cmpxchg_double is possible to use, otherwise slab_lock is taken).
+ *   They also don't disable preemption or migration or irqs. They rely on
+ *   the transaction id (tid) field to detect being preempted or moved to
+ *   another cpu.
+ *
+ *   irq, preemption, migration considerations
+ *
+ *   Interrupts are disabled as part of list_lock or local_lock operations, or
+ *   around the slab_lock operation, in order to make the slab allocator safe
+ *   to use in the context of an irq.
+ *
+ *   In addition, preemption (or migration on PREEMPT_RT) is disabled in the
+ *   allocation slowpath, bulk allocation, and put_cpu_partial(), so that the
+ *   local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer
+ *   doesn't have to be revalidated in each section protected by the local lock.
  *
  * SLUB assigns one slab for allocation to each processor.
  * Allocations only occur from these slabs called cpu slabs.
@@ -118,6 +156,26 @@
  * 			the fast path and disables lockless freelists.
  */
 
+/*
+ * We could simply use migrate_disable()/enable() but as long as it's a
+ * function call even on !PREEMPT_RT, use inline preempt_disable() there.
+ */
+#ifndef CONFIG_PREEMPT_RT
+#define slub_get_cpu_ptr(var)	get_cpu_ptr(var)
+#define slub_put_cpu_ptr(var)	put_cpu_ptr(var)
+#else
+#define slub_get_cpu_ptr(var)		\
+({					\
+	migrate_disable();		\
+	this_cpu_ptr(var);		\
+})
+#define slub_put_cpu_ptr(var)		\
+do {					\
+	(void)(var);			\
+	migrate_enable();		\
+} while (0)
+#endif
+
 #ifdef CONFIG_SLUB_DEBUG
 #ifdef CONFIG_SLUB_DEBUG_ON
 DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
@@ -359,25 +417,44 @@ static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
 /*
  * Per slab locking using the pagelock
  */
-static __always_inline void slab_lock(struct page *page)
+static __always_inline void __slab_lock(struct page *page)
 {
 	VM_BUG_ON_PAGE(PageTail(page), page);
 	bit_spin_lock(PG_locked, &page->flags);
 }
 
-static __always_inline void slab_unlock(struct page *page)
+static __always_inline void __slab_unlock(struct page *page)
 {
 	VM_BUG_ON_PAGE(PageTail(page), page);
 	__bit_spin_unlock(PG_locked, &page->flags);
 }
 
-/* Interrupts must be disabled (for the fallback code to work right) */
+static __always_inline void slab_lock(struct page *page, unsigned long *flags)
+{
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_save(*flags);
+	__slab_lock(page);
+}
+
+static __always_inline void slab_unlock(struct page *page, unsigned long *flags)
+{
+	__slab_unlock(page);
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_restore(*flags);
+}
+
+/*
+ * Interrupts must be disabled (for the fallback code to work right), typically
+ * by an _irqsave() lock variant. Except on PREEMPT_RT where locks are different
+ * so we disable interrupts as part of slab_[un]lock().
+ */
 static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
 		void *freelist_old, unsigned long counters_old,
 		void *freelist_new, unsigned long counters_new,
 		const char *n)
 {
-	VM_BUG_ON(!irqs_disabled());
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		lockdep_assert_irqs_disabled();
 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
 	if (s->flags & __CMPXCHG_DOUBLE) {
@@ -388,15 +465,18 @@ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page
 	} else
 #endif
 	{
-		slab_lock(page);
+		/* init to 0 to prevent spurious warnings */
+		unsigned long flags = 0;
+
+		slab_lock(page, &flags);
 		if (page->freelist == freelist_old &&
 					page->counters == counters_old) {
 			page->freelist = freelist_new;
 			page->counters = counters_new;
-			slab_unlock(page);
+			slab_unlock(page, &flags);
 			return true;
 		}
-		slab_unlock(page);
+		slab_unlock(page, &flags);
 	}
 
 	cpu_relax();
@@ -427,16 +507,16 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
 		unsigned long flags;
 
 		local_irq_save(flags);
-		slab_lock(page);
+		__slab_lock(page);
 		if (page->freelist == freelist_old &&
 					page->counters == counters_old) {
 			page->freelist = freelist_new;
 			page->counters = counters_new;
-			slab_unlock(page);
+			__slab_unlock(page);
 			local_irq_restore(flags);
 			return true;
 		}
-		slab_unlock(page);
+		__slab_unlock(page);
 		local_irq_restore(flags);
 	}
 
@@ -452,7 +532,7 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
 
 #ifdef CONFIG_SLUB_DEBUG
 static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
-static DEFINE_SPINLOCK(object_map_lock);
+static DEFINE_RAW_SPINLOCK(object_map_lock);
 
 static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
 		       struct page *page)
@@ -497,7 +577,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page)
 {
 	VM_BUG_ON(!irqs_disabled());
 
-	spin_lock(&object_map_lock);
+	raw_spin_lock(&object_map_lock);
 
 	__fill_map(object_map, s, page);
 
@@ -507,7 +587,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page)
 static void put_map(unsigned long *map) __releases(&object_map_lock)
 {
 	VM_BUG_ON(map != object_map);
-	spin_unlock(&object_map_lock);
+	raw_spin_unlock(&object_map_lock);
 }
 
 static inline unsigned int size_from_object(struct kmem_cache *s)
@@ -1009,8 +1089,6 @@ static int check_slab(struct kmem_cache *s, struct page *page)
 {
 	int maxobj;
 
-	VM_BUG_ON(!irqs_disabled());
-
 	if (!PageSlab(page)) {
 		slab_err(s, page, "Not a valid slab page");
 		return 0;
@@ -1271,11 +1349,11 @@ static noinline int free_debug_processing(
 	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
 	void *object = head;
 	int cnt = 0;
-	unsigned long flags;
+	unsigned long flags, flags2;
 	int ret = 0;
 
 	spin_lock_irqsave(&n->list_lock, flags);
-	slab_lock(page);
+	slab_lock(page, &flags2);
 
 	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
 		if (!check_slab(s, page))
@@ -1308,7 +1386,7 @@ out:
 		slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n",
 			 bulk_cnt, cnt);
 
-	slab_unlock(page);
+	slab_unlock(page, &flags2);
 	spin_unlock_irqrestore(&n->list_lock, flags);
 	if (!ret)
 		slab_fix(s, "Object at 0x%p not freed", object);
@@ -1809,9 +1887,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 	flags &= gfp_allowed_mask;
 
-	if (gfpflags_allow_blocking(flags))
-		local_irq_enable();
-
 	flags |= s->allocflags;
 
 	/*
@@ -1870,8 +1945,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	page->frozen = 1;
 
 out:
-	if (gfpflags_allow_blocking(flags))
-		local_irq_disable();
 	if (!page)
 		return NULL;
 
@@ -2010,18 +2083,24 @@ static inline void *acquire_slab(struct kmem_cache *s,
 	return freelist;
 }
 
+#ifdef CONFIG_SLUB_CPU_PARTIAL
 static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
+#else
+static inline void put_cpu_partial(struct kmem_cache *s, struct page *page,
+				   int drain) { }
+#endif
 static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
 
 /*
  * Try to allocate a partial slab from a specific node.
  */
 static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
-			      struct page **ret_page, gfp_t flags)
+			      struct page **ret_page, gfp_t gfpflags)
 {
 	struct page *page, *page2;
 	void *object = NULL;
 	unsigned int available = 0;
+	unsigned long flags;
 	int objects;
 
 	/*
@@ -2033,11 +2112,11 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
 	if (!n || !n->nr_partial)
 		return NULL;
 
-	spin_lock(&n->list_lock);
+	spin_lock_irqsave(&n->list_lock, flags);
 	list_for_each_entry_safe(page, page2, &n->partial, slab_list) {
 		void *t;
 
-		if (!pfmemalloc_match(page, flags))
+		if (!pfmemalloc_match(page, gfpflags))
 			continue;
 
 		t = acquire_slab(s, n, page, object == NULL, &objects);
@@ -2058,7 +2137,7 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
 			break;
 
 	}
-	spin_unlock(&n->list_lock);
+	spin_unlock_irqrestore(&n->list_lock, flags);
 	return object;
 }
 
@@ -2209,16 +2288,23 @@ static inline void note_cmpxchg_failure(const char *n,
 static void init_kmem_cache_cpus(struct kmem_cache *s)
 {
 	int cpu;
+	struct kmem_cache_cpu *c;
 
-	for_each_possible_cpu(cpu)
-		per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu);
+	for_each_possible_cpu(cpu) {
+		c = per_cpu_ptr(s->cpu_slab, cpu);
+		local_lock_init(&c->lock);
+		c->tid = init_tid(cpu);
+	}
 }
 
 /*
- * Remove the cpu slab
+ * Finishes removing the cpu slab. Merges cpu's freelist with page's freelist,
+ * unfreezes the slabs and puts it on the proper list.
+ * Assumes the slab has been already safely taken away from kmem_cache_cpu
+ * by the caller.
  */
 static void deactivate_slab(struct kmem_cache *s, struct page *page,
-				void *freelist, struct kmem_cache_cpu *c)
+			    void *freelist)
 {
 	enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
 	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
@@ -2226,6 +2312,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
 	enum slab_modes l = M_NONE, m = M_NONE;
 	void *nextfree, *freelist_iter, *freelist_tail;
 	int tail = DEACTIVATE_TO_HEAD;
+	unsigned long flags = 0;
 	struct page new;
 	struct page old;
 
@@ -2301,7 +2388,7 @@ redo:
 			 * that acquire_slab() will see a slab page that
 			 * is frozen
 			 */
-			spin_lock(&n->list_lock);
+			spin_lock_irqsave(&n->list_lock, flags);
 		}
 	} else {
 		m = M_FULL;
@@ -2312,7 +2399,7 @@ redo:
 			 * slabs from diagnostic functions will not see
 			 * any frozen slabs.
 			 */
-			spin_lock(&n->list_lock);
+			spin_lock_irqsave(&n->list_lock, flags);
 		}
 	}
 
@@ -2329,14 +2416,14 @@ redo:
 	}
 
 	l = m;
-	if (!__cmpxchg_double_slab(s, page,
+	if (!cmpxchg_double_slab(s, page,
 				old.freelist, old.counters,
 				new.freelist, new.counters,
 				"unfreezing slab"))
 		goto redo;
 
 	if (lock)
-		spin_unlock(&n->list_lock);
+		spin_unlock_irqrestore(&n->list_lock, flags);
 
 	if (m == M_PARTIAL)
 		stat(s, tail);
@@ -2347,38 +2434,29 @@ redo:
 		discard_slab(s, page);
 		stat(s, FREE_SLAB);
 	}
-
-	c->page = NULL;
-	c->freelist = NULL;
 }
 
-/*
- * Unfreeze all the cpu partial slabs.
- *
- * This function must be called with interrupts disabled
- * for the cpu using c (or some other guarantee must be there
- * to guarantee no concurrent accesses).
- */
-static void unfreeze_partials(struct kmem_cache *s,
-		struct kmem_cache_cpu *c)
-{
 #ifdef CONFIG_SLUB_CPU_PARTIAL
+static void __unfreeze_partials(struct kmem_cache *s, struct page *partial_page)
+{
 	struct kmem_cache_node *n = NULL, *n2 = NULL;
 	struct page *page, *discard_page = NULL;
+	unsigned long flags = 0;
 
-	while ((page = slub_percpu_partial(c))) {
+	while (partial_page) {
 		struct page new;
 		struct page old;
 
-		slub_set_percpu_partial(c, page);
+		page = partial_page;
+		partial_page = page->next;
 
 		n2 = get_node(s, page_to_nid(page));
 		if (n != n2) {
 			if (n)
-				spin_unlock(&n->list_lock);
+				spin_unlock_irqrestore(&n->list_lock, flags);
 
 			n = n2;
-			spin_lock(&n->list_lock);
+			spin_lock_irqsave(&n->list_lock, flags);
 		}
 
 		do {
@@ -2407,7 +2485,7 @@ static void unfreeze_partials(struct kmem_cache *s,
 	}
 
 	if (n)
-		spin_unlock(&n->list_lock);
+		spin_unlock_irqrestore(&n->list_lock, flags);
 
 	while (discard_page) {
 		page = discard_page;
@@ -2417,7 +2495,35 @@ static void unfreeze_partials(struct kmem_cache *s,
 		discard_slab(s, page);
 		stat(s, FREE_SLAB);
 	}
-#endif	/* CONFIG_SLUB_CPU_PARTIAL */
+}
+
+/*
+ * Unfreeze all the cpu partial slabs.
+ */
+static void unfreeze_partials(struct kmem_cache *s)
+{
+	struct page *partial_page;
+	unsigned long flags;
+
+	local_lock_irqsave(&s->cpu_slab->lock, flags);
+	partial_page = this_cpu_read(s->cpu_slab->partial);
+	this_cpu_write(s->cpu_slab->partial, NULL);
+	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+
+	if (partial_page)
+		__unfreeze_partials(s, partial_page);
+}
+
+static void unfreeze_partials_cpu(struct kmem_cache *s,
+				  struct kmem_cache_cpu *c)
+{
+	struct page *partial_page;
+
+	partial_page = slub_percpu_partial(c);
+	c->partial = NULL;
+
+	if (partial_page)
+		__unfreeze_partials(s, partial_page);
 }
 
 /*
@@ -2429,90 +2535,170 @@ static void unfreeze_partials(struct kmem_cache *s,
  */
 static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
 {
-#ifdef CONFIG_SLUB_CPU_PARTIAL
 	struct page *oldpage;
-	int pages;
-	int pobjects;
+	struct page *page_to_unfreeze = NULL;
+	unsigned long flags;
+	int pages = 0;
+	int pobjects = 0;
 
-	preempt_disable();
-	do {
-		pages = 0;
-		pobjects = 0;
-		oldpage = this_cpu_read(s->cpu_slab->partial);
+	local_lock_irqsave(&s->cpu_slab->lock, flags);
 
-		if (oldpage) {
+	oldpage = this_cpu_read(s->cpu_slab->partial);
+
+	if (oldpage) {
+		if (drain && oldpage->pobjects > slub_cpu_partial(s)) {
+			/*
+			 * Partial array is full. Move the existing set to the
+			 * per node partial list. Postpone the actual unfreezing
+			 * outside of the critical section.
+			 */
+			page_to_unfreeze = oldpage;
+			oldpage = NULL;
+		} else {
 			pobjects = oldpage->pobjects;
 			pages = oldpage->pages;
-			if (drain && pobjects > slub_cpu_partial(s)) {
-				unsigned long flags;
-				/*
-				 * partial array is full. Move the existing
-				 * set to the per node partial list.
-				 */
-				local_irq_save(flags);
-				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
-				local_irq_restore(flags);
-				oldpage = NULL;
-				pobjects = 0;
-				pages = 0;
-				stat(s, CPU_PARTIAL_DRAIN);
-			}
 		}
+	}
 
-		pages++;
-		pobjects += page->objects - page->inuse;
+	pages++;
+	pobjects += page->objects - page->inuse;
 
-		page->pages = pages;
-		page->pobjects = pobjects;
-		page->next = oldpage;
+	page->pages = pages;
+	page->pobjects = pobjects;
+	page->next = oldpage;
 
-	} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page)
-								!= oldpage);
-	preempt_enable();
-#endif	/* CONFIG_SLUB_CPU_PARTIAL */
+	this_cpu_write(s->cpu_slab->partial, page);
+
+	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+
+	if (page_to_unfreeze) {
+		__unfreeze_partials(s, page_to_unfreeze);
+		stat(s, CPU_PARTIAL_DRAIN);
+	}
 }
 
+#else	/* CONFIG_SLUB_CPU_PARTIAL */
+
+static inline void unfreeze_partials(struct kmem_cache *s) { }
+static inline void unfreeze_partials_cpu(struct kmem_cache *s,
+				  struct kmem_cache_cpu *c) { }
+
+#endif	/* CONFIG_SLUB_CPU_PARTIAL */
+
 static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
 {
-	stat(s, CPUSLAB_FLUSH);
-	deactivate_slab(s, c->page, c->freelist, c);
+	unsigned long flags;
+	struct page *page;
+	void *freelist;
+
+	local_lock_irqsave(&s->cpu_slab->lock, flags);
 
+	page = c->page;
+	freelist = c->freelist;
+
+	c->page = NULL;
+	c->freelist = NULL;
 	c->tid = next_tid(c->tid);
+
+	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+
+	if (page) {
+		deactivate_slab(s, page, freelist);
+		stat(s, CPUSLAB_FLUSH);
+	}
 }
 
+static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
+{
+	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+	void *freelist = c->freelist;
+	struct page *page = c->page;
+
+	c->page = NULL;
+	c->freelist = NULL;
+	c->tid = next_tid(c->tid);
+
+	if (page) {
+		deactivate_slab(s, page, freelist);
+		stat(s, CPUSLAB_FLUSH);
+	}
+
+	unfreeze_partials_cpu(s, c);
+}
+
+struct slub_flush_work {
+	struct work_struct work;
+	struct kmem_cache *s;
+	bool skip;
+};
+
 /*
  * Flush cpu slab.
  *
- * Called from IPI handler with interrupts disabled.
+ * Called from CPU work handler with migration disabled.
  */
-static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
+static void flush_cpu_slab(struct work_struct *w)
 {
-	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+	struct kmem_cache *s;
+	struct kmem_cache_cpu *c;
+	struct slub_flush_work *sfw;
+
+	sfw = container_of(w, struct slub_flush_work, work);
+
+	s = sfw->s;
+	c = this_cpu_ptr(s->cpu_slab);
 
 	if (c->page)
 		flush_slab(s, c);
 
-	unfreeze_partials(s, c);
+	unfreeze_partials(s);
 }
 
-static void flush_cpu_slab(void *d)
+static bool has_cpu_slab(int cpu, struct kmem_cache *s)
 {
-	struct kmem_cache *s = d;
+	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
 
-	__flush_cpu_slab(s, smp_processor_id());
+	return c->page || slub_percpu_partial(c);
 }
 
-static bool has_cpu_slab(int cpu, void *info)
+static DEFINE_MUTEX(flush_lock);
+static DEFINE_PER_CPU(struct slub_flush_work, slub_flush);
+
+static void flush_all_cpus_locked(struct kmem_cache *s)
 {
-	struct kmem_cache *s = info;
-	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+	struct slub_flush_work *sfw;
+	unsigned int cpu;
 
-	return c->page || slub_percpu_partial(c);
+	lockdep_assert_cpus_held();
+	mutex_lock(&flush_lock);
+
+	for_each_online_cpu(cpu) {
+		sfw = &per_cpu(slub_flush, cpu);
+		if (!has_cpu_slab(cpu, s)) {
+			sfw->skip = true;
+			continue;
+		}
+		INIT_WORK(&sfw->work, flush_cpu_slab);
+		sfw->skip = false;
+		sfw->s = s;
+		schedule_work_on(cpu, &sfw->work);
+	}
+
+	for_each_online_cpu(cpu) {
+		sfw = &per_cpu(slub_flush, cpu);
+		if (sfw->skip)
+			continue;
+		flush_work(&sfw->work);
+	}
+
+	mutex_unlock(&flush_lock);
 }
 
 static void flush_all(struct kmem_cache *s)
 {
-	on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1);
+	cpus_read_lock();
+	flush_all_cpus_locked(s);
+	cpus_read_unlock();
 }
 
 /*
@@ -2522,14 +2708,10 @@ static void flush_all(struct kmem_cache *s)
 static int slub_cpu_dead(unsigned int cpu)
 {
 	struct kmem_cache *s;
-	unsigned long flags;
 
 	mutex_lock(&slab_mutex);
-	list_for_each_entry(s, &slab_caches, list) {
-		local_irq_save(flags);
+	list_for_each_entry(s, &slab_caches, list)
 		__flush_cpu_slab(s, cpu);
-		local_irq_restore(flags);
-	}
 	mutex_unlock(&slab_mutex);
 	return 0;
 }
@@ -2620,6 +2802,19 @@ static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags)
 	return true;
 }
 
+/*
+ * A variant of pfmemalloc_match() that tests page flags without asserting
+ * PageSlab. Intended for opportunistic checks before taking a lock and
+ * rechecking that nobody else freed the page under us.
+ */
+static inline bool pfmemalloc_match_unsafe(struct page *page, gfp_t gfpflags)
+{
+	if (unlikely(__PageSlabPfmemalloc(page)))
+		return gfp_pfmemalloc_allowed(gfpflags);
+
+	return true;
+}
+
 /*
  * Check the page->freelist of a page and either transfer the freelist to the
  * per cpu freelist or deactivate the page.
@@ -2627,8 +2822,6 @@ static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags)
  * The page is still frozen if the return value is not NULL.
  *
  * If this function returns NULL then the page has been unfrozen.
- *
- * This function must be called with interrupt disabled.
  */
 static inline void *get_freelist(struct kmem_cache *s, struct page *page)
 {
@@ -2636,6 +2829,8 @@ static inline void *get_freelist(struct kmem_cache *s, struct page *page)
 	unsigned long counters;
 	void *freelist;
 
+	lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
+
 	do {
 		freelist = page->freelist;
 		counters = page->counters;
@@ -2670,7 +2865,7 @@ static inline void *get_freelist(struct kmem_cache *s, struct page *page)
  * we need to allocate a new slab. This is the slowest path since it involves
  * a call to the page allocator and the setup of a new slab.
  *
- * Version of __slab_alloc to use when we know that interrupts are
+ * Version of __slab_alloc to use when we know that preemption is
  * already disabled (which is the case for bulk allocation).
  */
 static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
@@ -2678,10 +2873,13 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 {
 	void *freelist;
 	struct page *page;
+	unsigned long flags;
 
 	stat(s, ALLOC_SLOWPATH);
 
-	page = c->page;
+reread_page:
+
+	page = READ_ONCE(c->page);
 	if (!page) {
 		/*
 		 * if the node is not online or has no normal memory, just
@@ -2704,8 +2902,7 @@ redo:
 			goto redo;
 		} else {
 			stat(s, ALLOC_NODE_MISMATCH);
-			deactivate_slab(s, page, c->freelist, c);
-			goto new_slab;
+			goto deactivate_slab;
 		}
 	}
 
@@ -2714,12 +2911,15 @@ redo:
 	 * PFMEMALLOC but right now, we are losing the pfmemalloc
 	 * information when the page leaves the per-cpu allocator
 	 */
-	if (unlikely(!pfmemalloc_match(page, gfpflags))) {
-		deactivate_slab(s, page, c->freelist, c);
-		goto new_slab;
+	if (unlikely(!pfmemalloc_match_unsafe(page, gfpflags)))
+		goto deactivate_slab;
+
+	/* must check again c->page in case we got preempted and it changed */
+	local_lock_irqsave(&s->cpu_slab->lock, flags);
+	if (unlikely(page != c->page)) {
+		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+		goto reread_page;
 	}
-
-	/* must check again c->freelist in case of cpu migration or IRQ */
 	freelist = c->freelist;
 	if (freelist)
 		goto load_freelist;
@@ -2728,6 +2928,7 @@ redo:
 
 	if (!freelist) {
 		c->page = NULL;
+		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
 		stat(s, DEACTIVATE_BYPASS);
 		goto new_slab;
 	}
@@ -2735,6 +2936,9 @@ redo:
 	stat(s, ALLOC_REFILL);
 
 load_freelist:
+
+	lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
+
 	/*
 	 * freelist is pointing to the list of objects to be used.
 	 * page is pointing to the page from which the objects are obtained.
@@ -2743,34 +2947,58 @@ load_freelist:
 	VM_BUG_ON(!c->page->frozen);
 	c->freelist = get_freepointer(s, freelist);
 	c->tid = next_tid(c->tid);
+	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
 	return freelist;
 
+deactivate_slab:
+
+	local_lock_irqsave(&s->cpu_slab->lock, flags);
+	if (page != c->page) {
+		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+		goto reread_page;
+	}
+	freelist = c->freelist;
+	c->page = NULL;
+	c->freelist = NULL;
+	local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+	deactivate_slab(s, page, freelist);
+
 new_slab:
 
 	if (slub_percpu_partial(c)) {
+		local_lock_irqsave(&s->cpu_slab->lock, flags);
+		if (unlikely(c->page)) {
+			local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+			goto reread_page;
+		}
+		if (unlikely(!slub_percpu_partial(c))) {
+			local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+			/* we were preempted and partial list got empty */
+			goto new_objects;
+		}
+
 		page = c->page = slub_percpu_partial(c);
 		slub_set_percpu_partial(c, page);
+		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
 		stat(s, CPU_PARTIAL_ALLOC);
 		goto redo;
 	}
 
+new_objects:
+
 	freelist = get_partial(s, gfpflags, node, &page);
-	if (freelist) {
-		c->page = page;
+	if (freelist)
 		goto check_new_page;
-	}
 
+	slub_put_cpu_ptr(s->cpu_slab);
 	page = new_slab(s, gfpflags, node);
+	c = slub_get_cpu_ptr(s->cpu_slab);
 
 	if (unlikely(!page)) {
 		slab_out_of_memory(s, gfpflags, node);
 		return NULL;
 	}
 
-	c = raw_cpu_ptr(s->cpu_slab);
-	if (c->page)
-		flush_slab(s, c);
-
 	/*
 	 * No other reference to the page yet so we can
 	 * muck around with it freely without cmpxchg
@@ -2779,43 +3007,81 @@ new_slab:
 	page->freelist = NULL;
 
 	stat(s, ALLOC_SLAB);
-	c->page = page;
 
 check_new_page:
-	if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags)))
-		goto load_freelist;
 
-	/* Only entered in the debug case */
-	if (kmem_cache_debug(s) &&
-			!alloc_debug_processing(s, page, freelist, addr))
-		goto new_slab;	/* Slab failed checks. Next slab needed */
+	if (kmem_cache_debug(s)) {
+		if (!alloc_debug_processing(s, page, freelist, addr)) {
+			/* Slab failed checks. Next slab needed */
+			goto new_slab;
+		} else {
+			/*
+			 * For debug case, we don't load freelist so that all
+			 * allocations go through alloc_debug_processing()
+			 */
+			goto return_single;
+		}
+	}
+
+	if (unlikely(!pfmemalloc_match(page, gfpflags)))
+		/*
+		 * For !pfmemalloc_match() case we don't load freelist so that
+		 * we don't make further mismatched allocations easier.
+		 */
+		goto return_single;
+
+retry_load_page:
+
+	local_lock_irqsave(&s->cpu_slab->lock, flags);
+	if (unlikely(c->page)) {
+		void *flush_freelist = c->freelist;
+		struct page *flush_page = c->page;
+
+		c->page = NULL;
+		c->freelist = NULL;
+		c->tid = next_tid(c->tid);
+
+		local_unlock_irqrestore(&s->cpu_slab->lock, flags);
+
+		deactivate_slab(s, flush_page, flush_freelist);
+
+		stat(s, CPUSLAB_FLUSH);
+
+		goto retry_load_page;
+	}
+	c->page = page;
+
+	goto load_freelist;
 
-	deactivate_slab(s, page, get_freepointer(s, freelist), c);
+return_single:
+
+	deactivate_slab(s, page, get_freepointer(s, freelist));
 	return freelist;
 }
 
 /*
- * Another one that disabled interrupt and compensates for possible
- * cpu changes by refetching the per cpu area pointer.
+ * A wrapper for ___slab_alloc() for contexts where preemption is not yet
+ * disabled. Compensates for possible cpu changes by refetching the per cpu area
+ * pointer.
  */
 static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 			  unsigned long addr, struct kmem_cache_cpu *c)
 {
 	void *p;
-	unsigned long flags;
 
-	local_irq_save(flags);
-#ifdef CONFIG_PREEMPTION
+#ifdef CONFIG_PREEMPT_COUNT
 	/*
 	 * We may have been preempted and rescheduled on a different
-	 * cpu before disabling interrupts. Need to reload cpu area
+	 * cpu before disabling preemption. Need to reload cpu area
 	 * pointer.
 	 */
-	c = this_cpu_ptr(s->cpu_slab);
+	c = slub_get_cpu_ptr(s->cpu_slab);
 #endif
 
 	p = ___slab_alloc(s, gfpflags, node, addr, c);
-	local_irq_restore(flags);
+#ifdef CONFIG_PREEMPT_COUNT
+	slub_put_cpu_ptr(s->cpu_slab);
+#endif
 	return p;
 }
 
@@ -2866,15 +3132,14 @@ redo:
 	 * reading from one cpu area. That does not matter as long
 	 * as we end up on the original cpu again when doing the cmpxchg.
 	 *
-	 * We should guarantee that tid and kmem_cache are retrieved on
-	 * the same cpu. It could be different if CONFIG_PREEMPTION so we need
-	 * to check if it is matched or not.
+	 * We must guarantee that tid and kmem_cache_cpu are retrieved on the
+	 * same cpu. We read first the kmem_cache_cpu pointer and use it to read
+	 * the tid. If we are preempted and switched to another cpu between the
+	 * two reads, it's OK as the two are still associated with the same cpu
+	 * and cmpxchg later will validate the cpu.
 	 */
-	do {
-		tid = this_cpu_read(s->cpu_slab->tid);
-		c = raw_cpu_ptr(s->cpu_slab);
-	} while (IS_ENABLED(CONFIG_PREEMPTION) &&
-		 unlikely(tid != READ_ONCE(c->tid)));
+	c = raw_cpu_ptr(s->cpu_slab);
+	tid = READ_ONCE(c->tid);
 
 	/*
 	 * Irqless object alloc/free algorithm used here depends on sequence
@@ -2895,7 +3160,15 @@ redo:
 
 	object = c->freelist;
 	page = c->page;
-	if (unlikely(!object || !page || !node_match(page, node))) {
+	/*
+	 * We cannot use the lockless fastpath on PREEMPT_RT because if a
+	 * slowpath has taken the local_lock_irqsave(), it is not protected
+	 * against a fast path operation in an irq handler. So we need to take
+	 * the slow path which uses local_lock. It is still relatively fast if
+	 * there is a suitable cpu freelist.
+	 */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT) ||
+	    unlikely(!object || !page || !node_match(page, node))) {
 		object = __slab_alloc(s, gfpflags, node, addr, c);
 	} else {
 		void *next_object = get_freepointer_safe(s, object);
@@ -3148,16 +3421,14 @@ redo:
 	 * data is retrieved via this pointer. If we are on the same cpu
 	 * during the cmpxchg then the free will succeed.
 	 */
-	do {
-		tid = this_cpu_read(s->cpu_slab->tid);
-		c = raw_cpu_ptr(s->cpu_slab);
-	} while (IS_ENABLED(CONFIG_PREEMPTION) &&
-		 unlikely(tid != READ_ONCE(c->tid)));
+	c = raw_cpu_ptr(s->cpu_slab);
+	tid = READ_ONCE(c->tid);
 
 	/* Same with comment on barrier() in slab_alloc_node() */
 	barrier();
 
 	if (likely(page == c->page)) {
+#ifndef CONFIG_PREEMPT_RT
 		void **freelist = READ_ONCE(c->freelist);
 
 		set_freepointer(s, tail_obj, freelist);
@@ -3170,6 +3441,31 @@ redo:
 			note_cmpxchg_failure("slab_free", s, tid);
 			goto redo;
 		}
+#else /* CONFIG_PREEMPT_RT */
+		/*
+		 * We cannot use the lockless fastpath on PREEMPT_RT because if
+		 * a slowpath has taken the local_lock_irqsave(), it is not
+		 * protected against a fast path operation in an irq handler. So
+		 * we need to take the local_lock. We shouldn't simply defer to
+		 * __slab_free() as that wouldn't use the cpu freelist at all.
+		 */
+		void **freelist;
+
+		local_lock(&s->cpu_slab->lock);
+		c = this_cpu_ptr(s->cpu_slab);
+		if (unlikely(page != c->page)) {
+			local_unlock(&s->cpu_slab->lock);
+			goto redo;
+		}
+		tid = c->tid;
+		freelist = c->freelist;
+
+		set_freepointer(s, tail_obj, freelist);
+		c->freelist = head;
+		c->tid = next_tid(tid);
+
+		local_unlock(&s->cpu_slab->lock);
+#endif
 		stat(s, FREE_FASTPATH);
 	} else
 		__slab_free(s, page, head, tail_obj, cnt, addr);
@@ -3347,8 +3643,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 	 * IRQs, which protects against PREEMPT and interrupts
 	 * handlers invoking normal fastpath.
 	 */
-	local_irq_disable();
-	c = this_cpu_ptr(s->cpu_slab);
+	c = slub_get_cpu_ptr(s->cpu_slab);
+	local_lock_irq(&s->cpu_slab->lock);
 
 	for (i = 0; i < size; i++) {
 		void *object = kfence_alloc(s, s->object_size, flags);
@@ -3369,6 +3665,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 			 */
 			c->tid = next_tid(c->tid);
 
+			local_unlock_irq(&s->cpu_slab->lock);
+
 			/*
 			 * Invoking slow path likely have side-effect
 			 * of re-populating per CPU c->freelist
@@ -3381,6 +3679,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 			c = this_cpu_ptr(s->cpu_slab);
 			maybe_wipe_obj_freeptr(s, p[i]);
 
+			local_lock_irq(&s->cpu_slab->lock);
+
 			continue; /* goto for-loop */
 		}
 		c->freelist = get_freepointer(s, object);
@@ -3388,7 +3688,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 		maybe_wipe_obj_freeptr(s, p[i]);
 	}
 	c->tid = next_tid(c->tid);
-	local_irq_enable();
+	local_unlock_irq(&s->cpu_slab->lock);
+	slub_put_cpu_ptr(s->cpu_slab);
 
 	/*
 	 * memcg and kmem_cache debug support and memory initialization.
@@ -3398,7 +3699,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 				slab_want_init_on_alloc(flags, s));
 	return i;
 error:
-	local_irq_enable();
+	slub_put_cpu_ptr(s->cpu_slab);
 	slab_post_alloc_hook(s, objcg, flags, i, p, false);
 	__kmem_cache_free_bulk(s, i, p);
 	return 0;
@@ -3912,11 +4213,12 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
 {
 #ifdef CONFIG_SLUB_DEBUG
 	void *addr = page_address(page);
+	unsigned long flags;
 	unsigned long *map;
 	void *p;
 
 	slab_err(s, page, text, s->name);
-	slab_lock(page);
+	slab_lock(page, &flags);
 
 	map = get_map(s, page);
 	for_each_object(p, s, addr, page->objects) {
@@ -3927,7 +4229,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
 		}
 	}
 	put_map(map);
-	slab_unlock(page);
+	slab_unlock(page, &flags);
 #endif
 }
 
@@ -3977,7 +4279,7 @@ int __kmem_cache_shutdown(struct kmem_cache *s)
 	int node;
 	struct kmem_cache_node *n;
 
-	flush_all(s);
+	flush_all_cpus_locked(s);
 	/* Attempt to free all objects */
 	for_each_kmem_cache_node(s, node, n) {
 		free_partial(s, n);
@@ -4253,7 +4555,7 @@ EXPORT_SYMBOL(kfree);
  * being allocated from last increasing the chance that the last objects
  * are freed in them.
  */
-int __kmem_cache_shrink(struct kmem_cache *s)
+static int __kmem_cache_do_shrink(struct kmem_cache *s)
 {
 	int node;
 	int i;
@@ -4265,7 +4567,6 @@ int __kmem_cache_shrink(struct kmem_cache *s)
 	unsigned long flags;
 	int ret = 0;
 
-	flush_all(s);
 	for_each_kmem_cache_node(s, node, n) {
 		INIT_LIST_HEAD(&discard);
 		for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
@@ -4315,13 +4616,21 @@ int __kmem_cache_shrink(struct kmem_cache *s)
 	return ret;
 }
 
+int __kmem_cache_shrink(struct kmem_cache *s)
+{
+	flush_all(s);
+	return __kmem_cache_do_shrink(s);
+}
+
 static int slab_mem_going_offline_callback(void *arg)
 {
 	struct kmem_cache *s;
 
 	mutex_lock(&slab_mutex);
-	list_for_each_entry(s, &slab_caches, list)
-		__kmem_cache_shrink(s);
+	list_for_each_entry(s, &slab_caches, list) {
+		flush_all_cpus_locked(s);
+		__kmem_cache_do_shrink(s);
+	}
 	mutex_unlock(&slab_mutex);
 
 	return 0;
@@ -4652,8 +4961,9 @@ static void validate_slab(struct kmem_cache *s, struct page *page,
 {
 	void *p;
 	void *addr = page_address(page);
+	unsigned long flags;
 
-	slab_lock(page);
+	slab_lock(page, &flags);
 
 	if (!check_slab(s, page) || !on_freelist(s, page, NULL))
 		goto unlock;
@@ -4668,7 +4978,7 @@ static void validate_slab(struct kmem_cache *s, struct page *page,
 			break;
 	}
 unlock:
-	slab_unlock(page);
+	slab_unlock(page, &flags);
 }
 
 static int validate_slab_node(struct kmem_cache *s,