1 files changed, 517 insertions, 179 deletions

diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index dd5aedee99e7..fa56c30833ff 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c
@@ -11,6 +11,9 @@
 #include <net/sock.h>
 #include <uapi/linux/sock_diag.h>
 #include <uapi/linux/btf.h>
+#include <linux/rcupdate.h>
+#include <linux/rcupdate_trace.h>
+#include <linux/rcupdate_wait.h>
 
 #define BPF_LOCAL_STORAGE_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_CLONE)
 
@@ -48,11 +51,21 @@ owner_storage(struct bpf_local_storage_map *smap, void *owner)
 	return map->ops->map_owner_storage_ptr(owner);
 }
 
+static bool selem_linked_to_storage_lockless(const struct bpf_local_storage_elem *selem)
+{
+	return !hlist_unhashed_lockless(&selem->snode);
+}
+
 static bool selem_linked_to_storage(const struct bpf_local_storage_elem *selem)
 {
 	return !hlist_unhashed(&selem->snode);
 }
 
+static bool selem_linked_to_map_lockless(const struct bpf_local_storage_elem *selem)
+{
+	return !hlist_unhashed_lockless(&selem->map_node);
+}
+
 static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem)
 {
 	return !hlist_unhashed(&selem->map_node);
@@ -60,18 +73,36 @@ static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem)
 
 struct bpf_local_storage_elem *
 bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
-		void *value, bool charge_mem)
+		void *value, bool charge_mem, bool swap_uptrs, gfp_t gfp_flags)
 {
 	struct bpf_local_storage_elem *selem;
 
 	if (charge_mem && mem_charge(smap, owner, smap->elem_size))
 		return NULL;
 
-	selem = bpf_map_kzalloc(&smap->map, smap->elem_size,
-				GFP_ATOMIC | __GFP_NOWARN);
+	if (smap->bpf_ma) {
+		selem = bpf_mem_cache_alloc_flags(&smap->selem_ma, gfp_flags);
+		if (selem)
+			/* Keep the original bpf_map_kzalloc behavior
+			 * before started using the bpf_mem_cache_alloc.
+			 *
+			 * No need to use zero_map_value. The bpf_selem_free()
+			 * only does bpf_mem_cache_free when there is
+			 * no other bpf prog is using the selem.
+			 */
+			memset(SDATA(selem)->data, 0, smap->map.value_size);
+	} else {
+		selem = bpf_map_kzalloc(&smap->map, smap->elem_size,
+					gfp_flags | __GFP_NOWARN);
+	}
+
 	if (selem) {
-		if (value)
-			memcpy(SDATA(selem)->data, value, smap->map.value_size);
+		if (value) {
+			/* No need to call check_and_init_map_value as memory is zero init */
+			copy_map_value(&smap->map, SDATA(selem)->data, value);
+			if (swap_uptrs)
+				bpf_obj_swap_uptrs(smap->map.record, SDATA(selem)->data, value);
+		}
 		return selem;
 	}
 
@@ -81,19 +112,185 @@ bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
 	return NULL;
 }
 
+/* rcu tasks trace callback for bpf_ma == false */
+static void __bpf_local_storage_free_trace_rcu(struct rcu_head *rcu)
+{
+	struct bpf_local_storage *local_storage;
+
+	/* If RCU Tasks Trace grace period implies RCU grace period, do
+	 * kfree(), else do kfree_rcu().
+	 */
+	local_storage = container_of(rcu, struct bpf_local_storage, rcu);
+	if (rcu_trace_implies_rcu_gp())
+		kfree(local_storage);
+	else
+		kfree_rcu(local_storage, rcu);
+}
+
+static void bpf_local_storage_free_rcu(struct rcu_head *rcu)
+{
+	struct bpf_local_storage *local_storage;
+
+	local_storage = container_of(rcu, struct bpf_local_storage, rcu);
+	bpf_mem_cache_raw_free(local_storage);
+}
+
+static void bpf_local_storage_free_trace_rcu(struct rcu_head *rcu)
+{
+	if (rcu_trace_implies_rcu_gp())
+		bpf_local_storage_free_rcu(rcu);
+	else
+		call_rcu(rcu, bpf_local_storage_free_rcu);
+}
+
+/* Handle bpf_ma == false */
+static void __bpf_local_storage_free(struct bpf_local_storage *local_storage,
+				     bool vanilla_rcu)
+{
+	if (vanilla_rcu)
+		kfree_rcu(local_storage, rcu);
+	else
+		call_rcu_tasks_trace(&local_storage->rcu,
+				     __bpf_local_storage_free_trace_rcu);
+}
+
+static void bpf_local_storage_free(struct bpf_local_storage *local_storage,
+				   struct bpf_local_storage_map *smap,
+				   bool bpf_ma, bool reuse_now)
+{
+	if (!local_storage)
+		return;
+
+	if (!bpf_ma) {
+		__bpf_local_storage_free(local_storage, reuse_now);
+		return;
+	}
+
+	if (!reuse_now) {
+		call_rcu_tasks_trace(&local_storage->rcu,
+				     bpf_local_storage_free_trace_rcu);
+		return;
+	}
+
+	if (smap)
+		bpf_mem_cache_free(&smap->storage_ma, local_storage);
+	else
+		/* smap could be NULL if the selem that triggered
+		 * this 'local_storage' creation had been long gone.
+		 * In this case, directly do call_rcu().
+		 */
+		call_rcu(&local_storage->rcu, bpf_local_storage_free_rcu);
+}
+
+/* rcu tasks trace callback for bpf_ma == false */
+static void __bpf_selem_free_trace_rcu(struct rcu_head *rcu)
+{
+	struct bpf_local_storage_elem *selem;
+
+	selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
+	if (rcu_trace_implies_rcu_gp())
+		kfree(selem);
+	else
+		kfree_rcu(selem, rcu);
+}
+
+/* Handle bpf_ma == false */
+static void __bpf_selem_free(struct bpf_local_storage_elem *selem,
+			     bool vanilla_rcu)
+{
+	if (vanilla_rcu)
+		kfree_rcu(selem, rcu);
+	else
+		call_rcu_tasks_trace(&selem->rcu, __bpf_selem_free_trace_rcu);
+}
+
+static void bpf_selem_free_rcu(struct rcu_head *rcu)
+{
+	struct bpf_local_storage_elem *selem;
+	struct bpf_local_storage_map *smap;
+
+	selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
+	/* The bpf_local_storage_map_free will wait for rcu_barrier */
+	smap = rcu_dereference_check(SDATA(selem)->smap, 1);
+
+	migrate_disable();
+	bpf_obj_free_fields(smap->map.record, SDATA(selem)->data);
+	migrate_enable();
+	bpf_mem_cache_raw_free(selem);
+}
+
+static void bpf_selem_free_trace_rcu(struct rcu_head *rcu)
+{
+	if (rcu_trace_implies_rcu_gp())
+		bpf_selem_free_rcu(rcu);
+	else
+		call_rcu(rcu, bpf_selem_free_rcu);
+}
+
+void bpf_selem_free(struct bpf_local_storage_elem *selem,
+		    struct bpf_local_storage_map *smap,
+		    bool reuse_now)
+{
+	if (!smap->bpf_ma) {
+		/* Only task storage has uptrs and task storage
+		 * has moved to bpf_mem_alloc. Meaning smap->bpf_ma == true
+		 * for task storage, so this bpf_obj_free_fields() won't unpin
+		 * any uptr.
+		 */
+		bpf_obj_free_fields(smap->map.record, SDATA(selem)->data);
+		__bpf_selem_free(selem, reuse_now);
+		return;
+	}
+
+	if (reuse_now) {
+		/* reuse_now == true only happens when the storage owner
+		 * (e.g. task_struct) is being destructed or the map itself
+		 * is being destructed (ie map_free). In both cases,
+		 * no bpf prog can have a hold on the selem. It is
+		 * safe to unpin the uptrs and free the selem now.
+		 */
+		bpf_obj_free_fields(smap->map.record, SDATA(selem)->data);
+		/* Instead of using the vanilla call_rcu(),
+		 * bpf_mem_cache_free will be able to reuse selem
+		 * immediately.
+		 */
+		bpf_mem_cache_free(&smap->selem_ma, selem);
+		return;
+	}
+
+	call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_trace_rcu);
+}
+
+static void bpf_selem_free_list(struct hlist_head *list, bool reuse_now)
+{
+	struct bpf_local_storage_elem *selem;
+	struct bpf_local_storage_map *smap;
+	struct hlist_node *n;
+
+	/* The "_safe" iteration is needed.
+	 * The loop is not removing the selem from the list
+	 * but bpf_selem_free will use the selem->rcu_head
+	 * which is union-ized with the selem->free_node.
+	 */
+	hlist_for_each_entry_safe(selem, n, list, free_node) {
+		smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
+		bpf_selem_free(selem, smap, reuse_now);
+	}
+}
+
 /* local_storage->lock must be held and selem->local_storage == local_storage.
  * The caller must ensure selem->smap is still valid to be
  * dereferenced for its smap->elem_size and smap->cache_idx.
  */
-bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
-				     struct bpf_local_storage_elem *selem,
-				     bool uncharge_mem)
+static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
+					    struct bpf_local_storage_elem *selem,
+					    bool uncharge_mem, struct hlist_head *free_selem_list)
 {
 	struct bpf_local_storage_map *smap;
 	bool free_local_storage;
 	void *owner;
 
-	smap = rcu_dereference(SDATA(selem)->smap);
+	smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
 	owner = local_storage->owner;
 
 	/* All uncharging on the owner must be done first.
@@ -117,13 +314,13 @@ bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
 		 * will be done by the caller.
 		 *
 		 * Although the unlock will be done under
-		 * rcu_read_lock(),  it is more intutivie to
-		 * read if kfree_rcu(local_storage, rcu) is done
+		 * rcu_read_lock(),  it is more intuitive to
+		 * read if the freeing of the storage is done
 		 * after the raw_spin_unlock_bh(&local_storage->lock).
 		 *
 		 * Hence, a "bool free_local_storage" is returned
-		 * to the caller which then calls the kfree_rcu()
-		 * after unlock.
+		 * to the caller which then calls then frees the storage after
+		 * all the RCU grace periods have expired.
 		 */
 	}
 	hlist_del_init_rcu(&selem->snode);
@@ -131,29 +328,78 @@ bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
 	    SDATA(selem))
 		RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL);
 
-	kfree_rcu(selem, rcu);
+	hlist_add_head(&selem->free_node, free_selem_list);
+
+	if (rcu_access_pointer(local_storage->smap) == smap)
+		RCU_INIT_POINTER(local_storage->smap, NULL);
 
 	return free_local_storage;
 }
 
-static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem)
+static bool check_storage_bpf_ma(struct bpf_local_storage *local_storage,
+				 struct bpf_local_storage_map *storage_smap,
+				 struct bpf_local_storage_elem *selem)
+{
+
+	struct bpf_local_storage_map *selem_smap;
+
+	/* local_storage->smap may be NULL. If it is, get the bpf_ma
+	 * from any selem in the local_storage->list. The bpf_ma of all
+	 * local_storage and selem should have the same value
+	 * for the same map type.
+	 *
+	 * If the local_storage->list is already empty, the caller will not
+	 * care about the bpf_ma value also because the caller is not
+	 * responsible to free the local_storage.
+	 */
+
+	if (storage_smap)
+		return storage_smap->bpf_ma;
+
+	if (!selem) {
+		struct hlist_node *n;
+
+		n = rcu_dereference_check(hlist_first_rcu(&local_storage->list),
+					  bpf_rcu_lock_held());
+		if (!n)
+			return false;
+
+		selem = hlist_entry(n, struct bpf_local_storage_elem, snode);
+	}
+	selem_smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
+
+	return selem_smap->bpf_ma;
+}
+
+static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem,
+				     bool reuse_now)
 {
+	struct bpf_local_storage_map *storage_smap;
 	struct bpf_local_storage *local_storage;
-	bool free_local_storage = false;
+	bool bpf_ma, free_local_storage = false;
+	HLIST_HEAD(selem_free_list);
+	unsigned long flags;
 
-	if (unlikely(!selem_linked_to_storage(selem)))
+	if (unlikely(!selem_linked_to_storage_lockless(selem)))
 		/* selem has already been unlinked from sk */
 		return;
 
-	local_storage = rcu_dereference(selem->local_storage);
-	raw_spin_lock_bh(&local_storage->lock);
+	local_storage = rcu_dereference_check(selem->local_storage,
+					      bpf_rcu_lock_held());
+	storage_smap = rcu_dereference_check(local_storage->smap,
+					     bpf_rcu_lock_held());
+	bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, selem);
+
+	raw_spin_lock_irqsave(&local_storage->lock, flags);
 	if (likely(selem_linked_to_storage(selem)))
 		free_local_storage = bpf_selem_unlink_storage_nolock(
-			local_storage, selem, true);
-	raw_spin_unlock_bh(&local_storage->lock);
+			local_storage, selem, true, &selem_free_list);
+	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
+
+	bpf_selem_free_list(&selem_free_list, reuse_now);
 
 	if (free_local_storage)
-		kfree_rcu(local_storage, rcu);
+		bpf_local_storage_free(local_storage, storage_smap, bpf_ma, reuse_now);
 }
 
 void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
@@ -163,80 +409,61 @@ void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
 	hlist_add_head_rcu(&selem->snode, &local_storage->list);
 }
 
-void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem)
+static void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem)
 {
 	struct bpf_local_storage_map *smap;
 	struct bpf_local_storage_map_bucket *b;
+	unsigned long flags;
 
-	if (unlikely(!selem_linked_to_map(selem)))
+	if (unlikely(!selem_linked_to_map_lockless(selem)))
 		/* selem has already be unlinked from smap */
 		return;
 
-	smap = rcu_dereference(SDATA(selem)->smap);
+	smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
 	b = select_bucket(smap, selem);
-	raw_spin_lock_bh(&b->lock);
+	raw_spin_lock_irqsave(&b->lock, flags);
 	if (likely(selem_linked_to_map(selem)))
 		hlist_del_init_rcu(&selem->map_node);
-	raw_spin_unlock_bh(&b->lock);
+	raw_spin_unlock_irqrestore(&b->lock, flags);
 }
 
 void bpf_selem_link_map(struct bpf_local_storage_map *smap,
 			struct bpf_local_storage_elem *selem)
 {
 	struct bpf_local_storage_map_bucket *b = select_bucket(smap, selem);
+	unsigned long flags;
 
-	raw_spin_lock_bh(&b->lock);
+	raw_spin_lock_irqsave(&b->lock, flags);
 	RCU_INIT_POINTER(SDATA(selem)->smap, smap);
 	hlist_add_head_rcu(&selem->map_node, &b->list);
-	raw_spin_unlock_bh(&b->lock);
+	raw_spin_unlock_irqrestore(&b->lock, flags);
 }
 
-void bpf_selem_unlink(struct bpf_local_storage_elem *selem)
+void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now)
 {
 	/* Always unlink from map before unlinking from local_storage
 	 * because selem will be freed after successfully unlinked from
 	 * the local_storage.
 	 */
 	bpf_selem_unlink_map(selem);
-	__bpf_selem_unlink_storage(selem);
+	bpf_selem_unlink_storage(selem, reuse_now);
 }
 
-struct bpf_local_storage_data *
-bpf_local_storage_lookup(struct bpf_local_storage *local_storage,
-			 struct bpf_local_storage_map *smap,
-			 bool cacheit_lockit)
+void __bpf_local_storage_insert_cache(struct bpf_local_storage *local_storage,
+				      struct bpf_local_storage_map *smap,
+				      struct bpf_local_storage_elem *selem)
 {
-	struct bpf_local_storage_data *sdata;
-	struct bpf_local_storage_elem *selem;
-
-	/* Fast path (cache hit) */
-	sdata = rcu_dereference(local_storage->cache[smap->cache_idx]);
-	if (sdata && rcu_access_pointer(sdata->smap) == smap)
-		return sdata;
-
-	/* Slow path (cache miss) */
-	hlist_for_each_entry_rcu(selem, &local_storage->list, snode)
-		if (rcu_access_pointer(SDATA(selem)->smap) == smap)
-			break;
-
-	if (!selem)
-		return NULL;
-
-	sdata = SDATA(selem);
-	if (cacheit_lockit) {
-		/* spinlock is needed to avoid racing with the
-		 * parallel delete.  Otherwise, publishing an already
-		 * deleted sdata to the cache will become a use-after-free
-		 * problem in the next bpf_local_storage_lookup().
-		 */
-		raw_spin_lock_bh(&local_storage->lock);
-		if (selem_linked_to_storage(selem))
-			rcu_assign_pointer(local_storage->cache[smap->cache_idx],
-					   sdata);
-		raw_spin_unlock_bh(&local_storage->lock);
-	}
+	unsigned long flags;
 
-	return sdata;
+	/* spinlock is needed to avoid racing with the
+	 * parallel delete.  Otherwise, publishing an already
+	 * deleted sdata to the cache will become a use-after-free
+	 * problem in the next bpf_local_storage_lookup().
+	 */
+	raw_spin_lock_irqsave(&local_storage->lock, flags);
+	if (selem_linked_to_storage(selem))
+		rcu_assign_pointer(local_storage->cache[smap->cache_idx], SDATA(selem));
+	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
 }
 
 static int check_flags(const struct bpf_local_storage_data *old_sdata,
@@ -255,7 +482,8 @@ static int check_flags(const struct bpf_local_storage_data *old_sdata,
 
 int bpf_local_storage_alloc(void *owner,
 			    struct bpf_local_storage_map *smap,
-			    struct bpf_local_storage_elem *first_selem)
+			    struct bpf_local_storage_elem *first_selem,
+			    gfp_t gfp_flags)
 {
 	struct bpf_local_storage *prev_storage, *storage;
 	struct bpf_local_storage **owner_storage_ptr;
@@ -265,13 +493,17 @@ int bpf_local_storage_alloc(void *owner,
 	if (err)
 		return err;
 
-	storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
-				  GFP_ATOMIC | __GFP_NOWARN);
+	if (smap->bpf_ma)
+		storage = bpf_mem_cache_alloc_flags(&smap->storage_ma, gfp_flags);
+	else
+		storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
+					  gfp_flags | __GFP_NOWARN);
 	if (!storage) {
 		err = -ENOMEM;
 		goto uncharge;
 	}
 
+	RCU_INIT_POINTER(storage->smap, smap);
 	INIT_HLIST_HEAD(&storage->list);
 	raw_spin_lock_init(&storage->lock);
 	storage->owner = owner;
@@ -301,7 +533,8 @@ int bpf_local_storage_alloc(void *owner,
 		 * bucket->list, first_selem can be freed immediately
 		 * (instead of kfree_rcu) because
 		 * bpf_local_storage_map_free() does a
-		 * synchronize_rcu() before walking the bucket->list.
+		 * synchronize_rcu_mult (waiting for both sleepable and
+		 * normal programs) before walking the bucket->list.
 		 * Hence, no one is accessing selem from the
 		 * bucket->list under rcu_read_lock().
 		 */
@@ -310,7 +543,7 @@ int bpf_local_storage_alloc(void *owner,
 	return 0;
 
 uncharge:
-	kfree(storage);
+	bpf_local_storage_free(storage, smap, smap->bpf_ma, true);
 	mem_uncharge(smap, owner, sizeof(*storage));
 	return err;
 }
@@ -322,34 +555,40 @@ uncharge:
  */
 struct bpf_local_storage_data *
 bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
-			 void *value, u64 map_flags)
+			 void *value, u64 map_flags, bool swap_uptrs, gfp_t gfp_flags)
 {
 	struct bpf_local_storage_data *old_sdata = NULL;
-	struct bpf_local_storage_elem *selem;
+	struct bpf_local_storage_elem *alloc_selem, *selem = NULL;
 	struct bpf_local_storage *local_storage;
+	HLIST_HEAD(old_selem_free_list);
+	unsigned long flags;
 	int err;
 
 	/* BPF_EXIST and BPF_NOEXIST cannot be both set */
 	if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) ||
 	    /* BPF_F_LOCK can only be used in a value with spin_lock */
 	    unlikely((map_flags & BPF_F_LOCK) &&
-		     !map_value_has_spin_lock(&smap->map)))
+		     !btf_record_has_field(smap->map.record, BPF_SPIN_LOCK)))
 		return ERR_PTR(-EINVAL);
 
-	local_storage = rcu_dereference(*owner_storage(smap, owner));
+	if (gfp_flags == GFP_KERNEL && (map_flags & ~BPF_F_LOCK) != BPF_NOEXIST)
+		return ERR_PTR(-EINVAL);
+
+	local_storage = rcu_dereference_check(*owner_storage(smap, owner),
+					      bpf_rcu_lock_held());
 	if (!local_storage || hlist_empty(&local_storage->list)) {
 		/* Very first elem for the owner */
 		err = check_flags(NULL, map_flags);
 		if (err)
 			return ERR_PTR(err);
 
-		selem = bpf_selem_alloc(smap, owner, value, true);
+		selem = bpf_selem_alloc(smap, owner, value, true, swap_uptrs, gfp_flags);
 		if (!selem)
 			return ERR_PTR(-ENOMEM);
 
-		err = bpf_local_storage_alloc(owner, smap, selem);
+		err = bpf_local_storage_alloc(owner, smap, selem, gfp_flags);
 		if (err) {
-			kfree(selem);
+			bpf_selem_free(selem, smap, true);
 			mem_uncharge(smap, owner, smap->elem_size);
 			return ERR_PTR(err);
 		}
@@ -367,14 +606,21 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 		err = check_flags(old_sdata, map_flags);
 		if (err)
 			return ERR_PTR(err);
-		if (old_sdata && selem_linked_to_storage(SELEM(old_sdata))) {
+		if (old_sdata && selem_linked_to_storage_lockless(SELEM(old_sdata))) {
 			copy_map_value_locked(&smap->map, old_sdata->data,
 					      value, false);
 			return old_sdata;
 		}
 	}
 
-	raw_spin_lock_bh(&local_storage->lock);
+	/* A lookup has just been done before and concluded a new selem is
+	 * needed. The chance of an unnecessary alloc is unlikely.
+	 */
+	alloc_selem = selem = bpf_selem_alloc(smap, owner, value, true, swap_uptrs, gfp_flags);
+	if (!alloc_selem)
+		return ERR_PTR(-ENOMEM);
+
+	raw_spin_lock_irqsave(&local_storage->lock, flags);
 
 	/* Recheck local_storage->list under local_storage->lock */
 	if (unlikely(hlist_empty(&local_storage->list))) {
@@ -384,13 +630,13 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 		 * simple.
 		 */
 		err = -EAGAIN;
-		goto unlock_err;
+		goto unlock;
 	}
 
 	old_sdata = bpf_local_storage_lookup(local_storage, smap, false);
 	err = check_flags(old_sdata, map_flags);
 	if (err)
-		goto unlock_err;
+		goto unlock;
 
 	if (old_sdata && (map_flags & BPF_F_LOCK)) {
 		copy_map_value_locked(&smap->map, old_sdata->data, value,
@@ -399,21 +645,7 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 		goto unlock;
 	}
 
-	/* local_storage->lock is held.  Hence, we are sure
-	 * we can unlink and uncharge the old_sdata successfully
-	 * later.  Hence, instead of charging the new selem now
-	 * and then uncharge the old selem later (which may cause
-	 * a potential but unnecessary charge failure),  avoid taking
-	 * a charge at all here (the "!old_sdata" check) and the
-	 * old_sdata will not be uncharged later during
-	 * bpf_selem_unlink_storage_nolock().
-	 */
-	selem = bpf_selem_alloc(smap, owner, value, !old_sdata);
-	if (!selem) {
-		err = -ENOMEM;
-		goto unlock_err;
-	}
-
+	alloc_selem = NULL;
 	/* First, link the new selem to the map */
 	bpf_selem_link_map(smap, selem);
 
@@ -424,19 +656,20 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 	if (old_sdata) {
 		bpf_selem_unlink_map(SELEM(old_sdata));
 		bpf_selem_unlink_storage_nolock(local_storage, SELEM(old_sdata),
-						false);
+						true, &old_selem_free_list);
 	}
 
 unlock:
-	raw_spin_unlock_bh(&local_storage->lock);
-	return SDATA(selem);
-
-unlock_err:
-	raw_spin_unlock_bh(&local_storage->lock);
-	return ERR_PTR(err);
+	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
+	bpf_selem_free_list(&old_selem_free_list, false);
+	if (alloc_selem) {
+		mem_uncharge(smap, owner, smap->elem_size);
+		bpf_selem_free(alloc_selem, smap, true);
+	}
+	return err ? ERR_PTR(err) : SDATA(selem);
 }
 
-u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache)
+static u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache)
 {
 	u64 min_usage = U64_MAX;
 	u16 i, res = 0;
@@ -460,20 +693,184 @@ u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache)
 	return res;
 }
 
-void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,
-				      u16 idx)
+static void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,
+					     u16 idx)
 {
 	spin_lock(&cache->idx_lock);
 	cache->idx_usage_counts[idx]--;
 	spin_unlock(&cache->idx_lock);
 }
 
-void bpf_local_storage_map_free(struct bpf_local_storage_map *smap)
+int bpf_local_storage_map_alloc_check(union bpf_attr *attr)
 {
+	if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK ||
+	    !(attr->map_flags & BPF_F_NO_PREALLOC) ||
+	    attr->max_entries ||
+	    attr->key_size != sizeof(int) || !attr->value_size ||
+	    /* Enforce BTF for userspace sk dumping */
+	    !attr->btf_key_type_id || !attr->btf_value_type_id)
+		return -EINVAL;
+
+	if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE)
+		return -E2BIG;
+
+	return 0;
+}
+
+int bpf_local_storage_map_check_btf(const struct bpf_map *map,
+				    const struct btf *btf,
+				    const struct btf_type *key_type,
+				    const struct btf_type *value_type)
+{
+	u32 int_data;
+
+	if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
+		return -EINVAL;
+
+	int_data = *(u32 *)(key_type + 1);
+	if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
+		return -EINVAL;
+
+	return 0;
+}
+
+void bpf_local_storage_destroy(struct bpf_local_storage *local_storage)
+{
+	struct bpf_local_storage_map *storage_smap;
 	struct bpf_local_storage_elem *selem;
+	bool bpf_ma, free_storage = false;
+	HLIST_HEAD(free_selem_list);
+	struct hlist_node *n;
+	unsigned long flags;
+
+	storage_smap = rcu_dereference_check(local_storage->smap, bpf_rcu_lock_held());
+	bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, NULL);
+
+	/* Neither the bpf_prog nor the bpf_map's syscall
+	 * could be modifying the local_storage->list now.
+	 * Thus, no elem can be added to or deleted from the
+	 * local_storage->list by the bpf_prog or by the bpf_map's syscall.
+	 *
+	 * It is racing with bpf_local_storage_map_free() alone
+	 * when unlinking elem from the local_storage->list and
+	 * the map's bucket->list.
+	 */
+	raw_spin_lock_irqsave(&local_storage->lock, flags);
+	hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
+		/* Always unlink from map before unlinking from
+		 * local_storage.
+		 */
+		bpf_selem_unlink_map(selem);
+		/* If local_storage list has only one element, the
+		 * bpf_selem_unlink_storage_nolock() will return true.
+		 * Otherwise, it will return false. The current loop iteration
+		 * intends to remove all local storage. So the last iteration
+		 * of the loop will set the free_cgroup_storage to true.
+		 */
+		free_storage = bpf_selem_unlink_storage_nolock(
+			local_storage, selem, true, &free_selem_list);
+	}
+	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
+
+	bpf_selem_free_list(&free_selem_list, true);
+
+	if (free_storage)
+		bpf_local_storage_free(local_storage, storage_smap, bpf_ma, true);
+}
+
+u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map)
+{
+	struct bpf_local_storage_map *smap = (struct bpf_local_storage_map *)map;
+	u64 usage = sizeof(*smap);
+
+	/* The dynamically callocated selems are not counted currently. */
+	usage += sizeof(*smap->buckets) * (1ULL << smap->bucket_log);
+	return usage;
+}
+
+/* When bpf_ma == true, the bpf_mem_alloc is used to allocate and free memory.
+ * A deadlock free allocator is useful for storage that the bpf prog can easily
+ * get a hold of the owner PTR_TO_BTF_ID in any context. eg. bpf_get_current_task_btf.
+ * The task and cgroup storage fall into this case. The bpf_mem_alloc reuses
+ * memory immediately. To be reuse-immediate safe, the owner destruction
+ * code path needs to go through a rcu grace period before calling
+ * bpf_local_storage_destroy().
+ *
+ * When bpf_ma == false, the kmalloc and kfree are used.
+ */
+struct bpf_map *
+bpf_local_storage_map_alloc(union bpf_attr *attr,
+			    struct bpf_local_storage_cache *cache,
+			    bool bpf_ma)
+{
+	struct bpf_local_storage_map *smap;
+	unsigned int i;
+	u32 nbuckets;
+	int err;
+
+	smap = bpf_map_area_alloc(sizeof(*smap), NUMA_NO_NODE);
+	if (!smap)
+		return ERR_PTR(-ENOMEM);
+	bpf_map_init_from_attr(&smap->map, attr);
+
+	nbuckets = roundup_pow_of_two(num_possible_cpus());
+	/* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */
+	nbuckets = max_t(u32, 2, nbuckets);
+	smap->bucket_log = ilog2(nbuckets);
+
+	smap->buckets = bpf_map_kvcalloc(&smap->map, nbuckets,
+					 sizeof(*smap->buckets), GFP_USER | __GFP_NOWARN);
+	if (!smap->buckets) {
+		err = -ENOMEM;
+		goto free_smap;
+	}
+
+	for (i = 0; i < nbuckets; i++) {
+		INIT_HLIST_HEAD(&smap->buckets[i].list);
+		raw_spin_lock_init(&smap->buckets[i].lock);
+	}
+
+	smap->elem_size = offsetof(struct bpf_local_storage_elem,
+				   sdata.data[attr->value_size]);
+
+	/* In PREEMPT_RT, kmalloc(GFP_ATOMIC) is still not safe in non
+	 * preemptible context. Thus, enforce all storages to use
+	 * bpf_mem_alloc when CONFIG_PREEMPT_RT is enabled.
+	 */
+	smap->bpf_ma = IS_ENABLED(CONFIG_PREEMPT_RT) ? true : bpf_ma;
+	if (smap->bpf_ma) {
+		err = bpf_mem_alloc_init(&smap->selem_ma, smap->elem_size, false);
+		if (err)
+			goto free_smap;
+
+		err = bpf_mem_alloc_init(&smap->storage_ma, sizeof(struct bpf_local_storage), false);
+		if (err) {
+			bpf_mem_alloc_destroy(&smap->selem_ma);
+			goto free_smap;
+		}
+	}
+
+	smap->cache_idx = bpf_local_storage_cache_idx_get(cache);
+	return &smap->map;
+
+free_smap:
+	kvfree(smap->buckets);
+	bpf_map_area_free(smap);
+	return ERR_PTR(err);
+}
+
+void bpf_local_storage_map_free(struct bpf_map *map,
+				struct bpf_local_storage_cache *cache,
+				int __percpu *busy_counter)
+{
 	struct bpf_local_storage_map_bucket *b;
+	struct bpf_local_storage_elem *selem;
+	struct bpf_local_storage_map *smap;
 	unsigned int i;
 
+	smap = (struct bpf_local_storage_map *)map;
+	bpf_local_storage_cache_idx_free(cache, smap->cache_idx);
+
 	/* Note that this map might be concurrently cloned from
 	 * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone
 	 * RCU read section to finish before proceeding. New RCU
@@ -497,7 +894,11 @@ void bpf_local_storage_map_free(struct bpf_local_storage_map *smap)
 		while ((selem = hlist_entry_safe(
 				rcu_dereference_raw(hlist_first_rcu(&b->list)),
 				struct bpf_local_storage_elem, map_node))) {
-			bpf_selem_unlink(selem);
+			if (busy_counter)
+				this_cpu_inc(*busy_counter);
+			bpf_selem_unlink(selem, true);
+			if (busy_counter)
+				this_cpu_dec(*busy_counter);
 			cond_resched_rcu();
 		}
 		rcu_read_unlock();
@@ -517,76 +918,13 @@ void bpf_local_storage_map_free(struct bpf_local_storage_map *smap)
 	 */
 	synchronize_rcu();
 
-	kvfree(smap->buckets);
-	kfree(smap);
-}
-
-int bpf_local_storage_map_alloc_check(union bpf_attr *attr)
-{
-	if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK ||
-	    !(attr->map_flags & BPF_F_NO_PREALLOC) ||
-	    attr->max_entries ||
-	    attr->key_size != sizeof(int) || !attr->value_size ||
-	    /* Enforce BTF for userspace sk dumping */
-	    !attr->btf_key_type_id || !attr->btf_value_type_id)
-		return -EINVAL;
-
-	if (!bpf_capable())
-		return -EPERM;
-
-	if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE)
-		return -E2BIG;
-
-	return 0;
-}
-
-struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr)
-{
-	struct bpf_local_storage_map *smap;
-	unsigned int i;
-	u32 nbuckets;
-
-	smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN | __GFP_ACCOUNT);
-	if (!smap)
-		return ERR_PTR(-ENOMEM);
-	bpf_map_init_from_attr(&smap->map, attr);
-
-	nbuckets = roundup_pow_of_two(num_possible_cpus());
-	/* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */
-	nbuckets = max_t(u32, 2, nbuckets);
-	smap->bucket_log = ilog2(nbuckets);
-
-	smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets,
-				 GFP_USER | __GFP_NOWARN | __GFP_ACCOUNT);
-	if (!smap->buckets) {
-		kfree(smap);
-		return ERR_PTR(-ENOMEM);
+	if (smap->bpf_ma) {
+		rcu_barrier_tasks_trace();
+		if (!rcu_trace_implies_rcu_gp())
+			rcu_barrier();
+		bpf_mem_alloc_destroy(&smap->selem_ma);
+		bpf_mem_alloc_destroy(&smap->storage_ma);
 	}
-
-	for (i = 0; i < nbuckets; i++) {
-		INIT_HLIST_HEAD(&smap->buckets[i].list);
-		raw_spin_lock_init(&smap->buckets[i].lock);
-	}
-
-	smap->elem_size =
-		sizeof(struct bpf_local_storage_elem) + attr->value_size;
-
-	return smap;
-}
-
-int bpf_local_storage_map_check_btf(const struct bpf_map *map,
-				    const struct btf *btf,
-				    const struct btf_type *key_type,
-				    const struct btf_type *value_type)
-{
-	u32 int_data;
-
-	if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
-		return -EINVAL;
-
-	int_data = *(u32 *)(key_type + 1);
-	if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
-		return -EINVAL;
-
-	return 0;
+	kvfree(smap->buckets);
+	bpf_map_area_free(smap);
 }