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--- libmalloc/libmalloc-283.100.5/src/magazine_tiny.c
+++ libmalloc/libmalloc-374.100.5/src/magazine_tiny.c
@@ -44,13 +44,13 @@
 {
 #if CONFIG_TINY_USES_HYPER_SHIFT
 	if (os_likely(_os_cpu_number_override == -1)) {
-		return _os_cpu_number() >> hyper_shift;
+		return _malloc_cpu_number() >> hyper_shift;
 	} else {
 		return _os_cpu_number_override >> hyper_shift;
 	}
 #else // CONFIG_SMALL_USES_HYPER_SHIFT
 	if (os_likely(_os_cpu_number_override == -1)) {
-		return _os_cpu_number();
+		return _malloc_cpu_number();
 	} else {
 		return _os_cpu_number_override;
 	}
@@ -81,7 +81,11 @@
 		if (BITARRAY_BIT(prev_header, prev_index)) {
 			return 1;
 		}
-		return TINY_PREVIOUS_MSIZE(ptr);
+		msize_t *prev_msize_ptr = &TINY_PREVIOUS_MSIZE(ptr);
+		// This is a speculative read of potentially in-use app memory, we need
+		// to use _malloc_read_uint16_via_rsp to avoid triggering warnings in
+		// memory diagnostic tools.
+		return _malloc_read_uint16_via_rsp(prev_msize_ptr);
 	}
 	// don't read possibly unmapped memory before the beginning of the region
 	return 0;
@@ -836,18 +840,30 @@
 	for (mag_index = 0; mag_index < rack->num_magazines; mag_index++) {
 		size_t index;
 		for (index = 0; index < rack->region_generation->num_regions_allocated; ++index) {
-			SZONE_LOCK(TINY_SZONE_FROM_RACK(rack));
+			rack_region_lock(rack);
 
 			region_t tiny = rack->region_generation->hashed_regions[index];
 			if (!tiny || tiny == HASHRING_REGION_DEALLOCATED) {
-				SZONE_UNLOCK(TINY_SZONE_FROM_RACK(rack));
+				rack_region_unlock(rack);
 				continue;
 			}
 
+			region_trailer_t *trailer = REGION_TRAILER_FOR_TINY_REGION(tiny);
+			// Make sure that the owning magazine doesn't try and take this out
+			// from under our feet.
+			trailer->dispose_flags |= RACK_DISPOSE_DELAY;
+			rack_region_unlock(rack);
+
 			magazine_t *mag_ptr = mag_lock_zine_for_region_trailer(rack->magazines,
-					REGION_TRAILER_FOR_TINY_REGION(tiny),
-					MAGAZINE_INDEX_FOR_TINY_REGION(tiny));
-			SZONE_UNLOCK(TINY_SZONE_FROM_RACK(rack));
+					trailer, MAGAZINE_INDEX_FOR_TINY_REGION(tiny));
+
+			// If acquiring the region lock was enough to prevent the owning
+			// magazine from deallocating the region, free it now so we don't
+			// do wasted work.
+			if (rack_region_maybe_dispose(rack, tiny, TINY_REGION_SIZE, trailer)) {
+				SZONE_MAGAZINE_PTR_UNLOCK(mag_ptr);
+				continue;
+			}
 
 			/* Ordering is important here, the magazine of a region may potentially change
 			 * during mag_lock_zine_for_region_trailer, so src_mag_index must be taken
@@ -861,6 +877,11 @@
 				continue;
 			}
 
+			if (REGION_TRAILER_FOR_TINY_REGION(tiny)->pinned_to_depot > 0) {
+				SZONE_MAGAZINE_PTR_UNLOCK(mag_ptr);
+				continue;
+			}
+
 			if (tiny == mag_ptr->mag_last_region && (mag_ptr->mag_bytes_free_at_end || mag_ptr->mag_bytes_free_at_start)) {
 				tiny_finalize_region(rack, mag_ptr);
 			}
@@ -875,7 +896,7 @@
 
 			SZONE_MAGAZINE_PTR_LOCK(tiny_depot_ptr);
 			MAGAZINE_INDEX_FOR_TINY_REGION(tiny) = DEPOT_MAGAZINE_INDEX;
-			REGION_TRAILER_FOR_TINY_REGION(tiny)->pinned_to_depot = 0;
+			MALLOC_ASSERT(REGION_TRAILER_FOR_TINY_REGION(tiny)->pinned_to_depot == 0);
 
 			size_t bytes_inplay = tiny_free_reattach_region(rack, tiny_depot_ptr, tiny);
 
@@ -981,22 +1002,32 @@
 	// Appropriate a Depot'd region that can satisfy requested msize.
 	region_trailer_t *node;
 	region_t sparse_region;
+	msize_t try_msize = msize;
 
 	while (1) {
-		sparse_region = tiny_find_msize_region(rack, depot_ptr, DEPOT_MAGAZINE_INDEX, msize);
+		sparse_region = tiny_find_msize_region(rack, depot_ptr, DEPOT_MAGAZINE_INDEX, try_msize);
 		if (NULL == sparse_region) { // Depot empty?
 			SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
 			return 0;
 		}
 
 		node = REGION_TRAILER_FOR_TINY_REGION(sparse_region);
-		if (0 >= node->pinned_to_depot) {
+		if (0 == node->pinned_to_depot) {
+			// Found one!
 			break;
 		}
 
-		SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
-		yield();
-		SZONE_MAGAZINE_PTR_LOCK(depot_ptr);
+		// Try the next msize up - maybe the head of its free list will be in
+		// a region we can use. Once we get the region we'll still allocate the
+		// original msize.
+		try_msize++;
+
+		if (try_msize > NUM_TINY_SLOTS) {
+			// Tried all the msizes but couldn't get a usable region. Let's
+			// give up for now and we'll allocate a new region from the kernel.
+			SZONE_MAGAZINE_PTR_UNLOCK(depot_ptr);
+			return 0;
+		}
 	}
 
 	// disconnect node from Depot
@@ -1007,7 +1038,7 @@
 
 	// Transfer ownership of the region
 	MAGAZINE_INDEX_FOR_TINY_REGION(sparse_region) = mag_index;
-	node->pinned_to_depot = 0;
+	MALLOC_ASSERT(node->pinned_to_depot == 0);
 
 	// Iterate the region putting its free entries on its new (locked) magazine's free list
 	size_t bytes_inplay = tiny_free_reattach_region(rack, tiny_mag_ptr, sparse_region);
@@ -1049,32 +1080,19 @@
 	int objects_in_use = tiny_free_detach_region(rack, depot_ptr, sparse_region);
 
 	if (0 == objects_in_use) {
-		// Invalidate the hash table entry for this region with HASHRING_REGION_DEALLOCATED.
-		// Using HASHRING_REGION_DEALLOCATED preserves the collision chain, using HASHRING_OPEN_ENTRY (0) would not.
-		rgnhdl_t pSlot = hash_lookup_region_no_lock(rack->region_generation->hashed_regions,
-				rack->region_generation->num_regions_allocated,
-				rack->region_generation->num_regions_allocated_shift,
-				sparse_region);
-
-		if (NULL == pSlot) {
-			malloc_zone_error(rack->debug_flags, true, "tiny_free_try_depot_unmap_no_lock hash lookup failed: %p\n", sparse_region);
+		if (!rack_region_remove(rack, sparse_region, node)) {
 			return NULL;
 		}
-		*pSlot = HASHRING_REGION_DEALLOCATED;
 		depot_ptr->num_bytes_in_magazine -= TINY_HEAP_SIZE;
 
-		// Atomically increment num_regions_dealloc
-#ifdef __LP64___
-		OSAtomicIncrement64(&rack->num_regions_dealloc);
-#else
-		OSAtomicIncrement32((int32_t *)&rack->num_regions_dealloc);
-#endif
-
 		// Caller will transfer ownership of the region back to the OS with no locks held
-		MAGMALLOC_DEALLOCREGION(TINY_SZONE_FROM_RACK(rack), (void *)sparse_region, TINY_REGION_SIZE); // DTrace USDT Probe
+		MAGMALLOC_DEALLOCREGION(TINY_SZONE_FROM_RACK(rack),
+				(void *)sparse_region, TINY_REGION_SIZE); // DTrace USDT Probe
 		return sparse_region;
 	} else {
-		malloc_zone_error(rack->debug_flags, true, "tiny_free_try_depot_unmap_no_lock objects_in_use not zero: %d\n", objects_in_use);
+		malloc_zone_error(rack->debug_flags, true,
+				"tiny_free_try_depot_unmap_no_lock objects_in_use not zero: %d\n",
+				objects_in_use);
 		return NULL;
 	}
 }
@@ -1147,10 +1165,13 @@
 	MAGMALLOC_RECIRCREGION(TINY_SZONE_FROM_RACK(rack), (int)mag_index, (void *)sparse_region, TINY_REGION_SIZE,
 						   (int)BYTES_USED_FOR_TINY_REGION(sparse_region)); // DTrace USDT Probe
 
-#if !CONFIG_AGGRESSIVE_MADVISE
-	// Mark free'd dirty pages with MADV_FREE to reduce memory pressure
-	tiny_free_scan_madvise_free(rack, depot_ptr, sparse_region);
-#endif
+#if CONFIG_AGGRESSIVE_MADVISE
+	if (!aggressive_madvise_enabled)
+#endif
+	{
+		// Mark free'd dirty pages with MADV_FREE to reduce memory pressure
+		tiny_free_scan_madvise_free(rack, depot_ptr, sparse_region);
+	}
 
 	// If the region is entirely empty vm_deallocate() it outside the depot lock
 	region_t r_dealloc = tiny_free_try_depot_unmap_no_lock(rack, depot_ptr, node);
@@ -1197,11 +1218,14 @@
 			return tiny_free_do_recirc_to_depot(rack, tiny_mag_ptr, mag_index);
 		}
 	} else {
-#if !CONFIG_AGGRESSIVE_MADVISE
-		// We are free'ing into the depot, so madvise as we do so unless we were madvising every incoming
-		// allocation anyway.
-		tiny_madvise_free_range_no_lock(rack, tiny_mag_ptr, region, headptr, headsize, ptr, msize);
-#endif
+#if CONFIG_AGGRESSIVE_MADVISE
+		if (!aggressive_madvise_enabled)
+#endif
+		{
+			// We are free'ing into the depot, so madvise as we do so unless we were madvising every incoming
+			// allocation anyway.
+			tiny_madvise_free_range_no_lock(rack, tiny_mag_ptr, region, headptr, headsize, ptr, msize);
+		}
 
 		if (0 < bytes_used || 0 < node->pinned_to_depot) {
 			/* Depot'd region is still live. Leave it in place on the Depot's recirculation list
@@ -1344,9 +1368,11 @@
 		tiny_mag_ptr->mag_num_objects--;
 	}
 #if CONFIG_AGGRESSIVE_MADVISE
-	// Platforms that want to madvise every freed allocation do so here, even if we continue
-	// on to use the recirc depot after.
-	tiny_madvise_free_range_no_lock(rack, tiny_mag_ptr, region, original_ptr, original_size, ptr, msize);
+	if (aggressive_madvise_enabled) {
+		// Platforms that want to madvise every freed allocation do so here, even if we continue
+		// on to use the recirc depot after.
+		tiny_madvise_free_range_no_lock(rack, tiny_mag_ptr, region, original_ptr, original_size, ptr, msize);
+	}
 #endif
 
 	// Caller must do SZONE_MAGAZINE_PTR_UNLOCK(tiny_mag_ptr) if this function
@@ -2355,9 +2381,6 @@
 static MALLOC_NOINLINE void
 free_tiny_botch(rack_t *rack, tiny_free_list_t *ptr)
 {
-	mag_index_t mag_index = MAGAZINE_INDEX_FOR_TINY_REGION(TINY_REGION_FOR_PTR(ptr));
-	magazine_t *tiny_mag_ptr = &(rack->magazines[mag_index]);
-	SZONE_MAGAZINE_PTR_UNLOCK(tiny_mag_ptr);
 	malloc_zone_error(rack->debug_flags, true, "Double free of object %p\n", ptr);
 }
 
@@ -2401,6 +2424,7 @@
 
 			/* check that we don't already have this pointer in the cache */
 			if (ptr == ptr2) {
+				SZONE_MAGAZINE_PTR_UNLOCK(tiny_mag_ptr);
 				free_tiny_botch(rack, ptr);
 				return;
 			}