Merge series "SLUB percpu sheaves"

This series adds an opt-in percpu array-based caching layer to SLUB.
It has evolved to a state where kmem caches with sheaves are compatible
with all SLUB features (slub_debug, SLUB_TINY, NUMA locality
considerations). The plan is therefore that it will be later enabled for
all kmem caches and replace the complicated cpu (partial) slabs code.

Note the name "sheaf" was invented by Matthew Wilcox so we don't call
the arrays magazines like the original Bonwick paper. The per-NUMA-node
cache of sheaves is thus called "barn".

This caching may seem similar to the arrays we had in SLAB, but there
are some important differences:

- deals differently with NUMA locality of freed objects, thus there are
  no per-node "shared" arrays (with possible lock contention) and no
  "alien" arrays that would need periodical flushing
  - instead, freeing remote objects (which is rare) bypasses the sheaves
  - percpu sheaves thus contain only local objects (modulo rare races
    and local node exhaustion)
  - NUMA restricted allocations and strict_numa mode is still honoured
- improves kfree_rcu() handling by reusing whole sheaves
- there is an API for obtaining a preallocated sheaf that can be used
  for guaranteed and efficient allocations in a restricted context, when
  the upper bound for needed objects is known but rarely reached
- opt-in, not used for every cache (for now)

The motivation comes mainly from the ongoing work related to VMA locking
scalability and the related maple tree operations. This is why VMA and
maple nodes caches are sheaf-enabled in the patchset.

A sheaf-enabled cache has the following expected advantages:

- Cheaper fast paths. For allocations, instead of local double cmpxchg,
  thanks to local_trylock() it becomes a preempt_disable() and no atomic
  operations. Same for freeing, which is otherwise a local double cmpxchg
  only for short term allocations (so the same slab is still active on the
  same cpu when freeing the object) and a more costly locked double
  cmpxchg otherwise.

- kfree_rcu() batching and recycling. kfree_rcu() will put objects to a
  separate percpu sheaf and only submit the whole sheaf to call_rcu()
  when full. After the grace period, the sheaf can be used for
  allocations, which is more efficient than freeing and reallocating
  individual slab objects (even with the batching done by kfree_rcu()
  implementation itself). In case only some cpus are allowed to handle rcu
  callbacks, the sheaf can still be made available to other cpus on the
  same node via the shared barn. The maple_node cache uses kfree_rcu() and
  thus can benefit from this.
  Note: this path is currently limited to !PREEMPT_RT

- Preallocation support. A prefilled sheaf can be privately borrowed to
  perform a short term operation that is not allowed to block in the
  middle and may need to allocate some objects. If an upper bound (worst
  case) for the number of allocations is known, but only much fewer
  allocations actually needed on average, borrowing and returning a sheaf
  is much more efficient then a bulk allocation for the worst case
  followed by a bulk free of the many unused objects. Maple tree write
  operations should benefit from this.

- Compatibility with slub_debug. When slub_debug is enabled for a cache,
  we simply don't create the percpu sheaves so that the debugging hooks
  (at the node partial list slowpaths) are reached as before. The same
  thing is done for CONFIG_SLUB_TINY. Sheaf preallocation still works by
  reusing the (ineffective) paths for requests exceeding the cache's
  sheaf_capacity. This is in line with the existing approach where
  debugging bypasses the fast paths and SLUB_TINY preferes memory
  savings over performance.

The above is adapted from the cover letter [1], which contains also
in-kernel microbenchmark results showing the lower overhead of sheaves.

Results from Suren Baghdasaryan [2] using a mmap/munmap microbenchmark
also show improvements.

Results from Sudarsan Mahendran [3] using will-it-scale show both
benefits and regressions, probably due to overall noisiness of those
tests.

Link: https://lore.kernel.org/all/20250910-slub-percpu-caches-v8-0-ca3099d8352c@suse.cz/ [1]
Link: https://lore.kernel.org/all/CAJuCfpEQ%3DRUgcAvRzE5jRrhhFpkm8E2PpBK9e9GhK26ZaJQt%3DQ@mail.gmail.com/ [2]
Link: https://lore.kernel.org/all/20250913000935.1021068-1-sudarsanm@google.com/ [3]

1 files changed, 26 insertions, 488 deletions

diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
index 172700fb7784..83260f2efb19 100644
--- a/tools/testing/radix-tree/maple.c
+++ b/tools/testing/radix-tree/maple.c
@@ -8,14 +8,6 @@
  * difficult to handle in kernel tests.
  */
 
-#define CONFIG_DEBUG_MAPLE_TREE
-#define CONFIG_MAPLE_SEARCH
-#define MAPLE_32BIT (MAPLE_NODE_SLOTS > 31)
-#include "test.h"
-#include <stdlib.h>
-#include <time.h>
-#include <linux/init.h>
-
 #define module_init(x)
 #define module_exit(x)
 #define MODULE_AUTHOR(x)
@@ -23,7 +15,9 @@
 #define MODULE_LICENSE(x)
 #define dump_stack()	assert(0)
 
-#include "../../../lib/maple_tree.c"
+#include "test.h"
+
+#include "../shared/maple-shim.c"
 #include "../../../lib/test_maple_tree.c"
 
 #define RCU_RANGE_COUNT 1000
@@ -63,430 +57,6 @@ struct rcu_reader_struct {
 	struct rcu_test_struct2 *test;
 };
 
-static int get_alloc_node_count(struct ma_state *mas)
-{
-	int count = 1;
-	struct maple_alloc *node = mas->alloc;
-
-	if (!node || ((unsigned long)node & 0x1))
-		return 0;
-	while (node->node_count) {
-		count += node->node_count;
-		node = node->slot[0];
-	}
-	return count;
-}
-
-static void check_mas_alloc_node_count(struct ma_state *mas)
-{
-	mas_node_count_gfp(mas, MAPLE_ALLOC_SLOTS + 1, GFP_KERNEL);
-	mas_node_count_gfp(mas, MAPLE_ALLOC_SLOTS + 3, GFP_KERNEL);
-	MT_BUG_ON(mas->tree, get_alloc_node_count(mas) != mas->alloc->total);
-	mas_destroy(mas);
-}
-
-/*
- * check_new_node() - Check the creation of new nodes and error path
- * verification.
- */
-static noinline void __init check_new_node(struct maple_tree *mt)
-{
-
-	struct maple_node *mn, *mn2, *mn3;
-	struct maple_alloc *smn;
-	struct maple_node *nodes[100];
-	int i, j, total;
-
-	MA_STATE(mas, mt, 0, 0);
-
-	check_mas_alloc_node_count(&mas);
-
-	/* Try allocating 3 nodes */
-	mtree_lock(mt);
-	mt_set_non_kernel(0);
-	/* request 3 nodes to be allocated. */
-	mas_node_count(&mas, 3);
-	/* Allocation request of 3. */
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != 3);
-	/* Allocate failed. */
-	MT_BUG_ON(mt, mas.node != MA_ERROR(-ENOMEM));
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-
-	MT_BUG_ON(mt, mas_allocated(&mas) != 3);
-	mn = mas_pop_node(&mas);
-	MT_BUG_ON(mt, not_empty(mn));
-	MT_BUG_ON(mt, mn == NULL);
-	MT_BUG_ON(mt, mas.alloc == NULL);
-	MT_BUG_ON(mt, mas.alloc->slot[0] == NULL);
-	mas_push_node(&mas, mn);
-	mas_reset(&mas);
-	mas_destroy(&mas);
-	mtree_unlock(mt);
-
-
-	/* Try allocating 1 node, then 2 more */
-	mtree_lock(mt);
-	/* Set allocation request to 1. */
-	mas_set_alloc_req(&mas, 1);
-	/* Check Allocation request of 1. */
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != 1);
-	mas_set_err(&mas, -ENOMEM);
-	/* Validate allocation request. */
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-	/* Eat the requested node. */
-	mn = mas_pop_node(&mas);
-	MT_BUG_ON(mt, not_empty(mn));
-	MT_BUG_ON(mt, mn == NULL);
-	MT_BUG_ON(mt, mn->slot[0] != NULL);
-	MT_BUG_ON(mt, mn->slot[1] != NULL);
-	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-
-	mn->parent = ma_parent_ptr(mn);
-	ma_free_rcu(mn);
-	mas.status = ma_start;
-	mas_destroy(&mas);
-	/* Allocate 3 nodes, will fail. */
-	mas_node_count(&mas, 3);
-	/* Drop the lock and allocate 3 nodes. */
-	mas_nomem(&mas, GFP_KERNEL);
-	/* Ensure 3 are allocated. */
-	MT_BUG_ON(mt, mas_allocated(&mas) != 3);
-	/* Allocation request of 0. */
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != 0);
-
-	MT_BUG_ON(mt, mas.alloc == NULL);
-	MT_BUG_ON(mt, mas.alloc->slot[0] == NULL);
-	MT_BUG_ON(mt, mas.alloc->slot[1] == NULL);
-	/* Ensure we counted 3. */
-	MT_BUG_ON(mt, mas_allocated(&mas) != 3);
-	/* Free. */
-	mas_reset(&mas);
-	mas_destroy(&mas);
-
-	/* Set allocation request to 1. */
-	mas_set_alloc_req(&mas, 1);
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != 1);
-	mas_set_err(&mas, -ENOMEM);
-	/* Validate allocation request. */
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-	MT_BUG_ON(mt, mas_allocated(&mas) != 1);
-	/* Check the node is only one node. */
-	mn = mas_pop_node(&mas);
-	MT_BUG_ON(mt, not_empty(mn));
-	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-	MT_BUG_ON(mt, mn == NULL);
-	MT_BUG_ON(mt, mn->slot[0] != NULL);
-	MT_BUG_ON(mt, mn->slot[1] != NULL);
-	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-	mas_push_node(&mas, mn);
-	MT_BUG_ON(mt, mas_allocated(&mas) != 1);
-	MT_BUG_ON(mt, mas.alloc->node_count);
-
-	mas_set_alloc_req(&mas, 2); /* request 2 more. */
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != 2);
-	mas_set_err(&mas, -ENOMEM);
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-	MT_BUG_ON(mt, mas_allocated(&mas) != 3);
-	MT_BUG_ON(mt, mas.alloc == NULL);
-	MT_BUG_ON(mt, mas.alloc->slot[0] == NULL);
-	MT_BUG_ON(mt, mas.alloc->slot[1] == NULL);
-	for (i = 2; i >= 0; i--) {
-		mn = mas_pop_node(&mas);
-		MT_BUG_ON(mt, mas_allocated(&mas) != i);
-		MT_BUG_ON(mt, !mn);
-		MT_BUG_ON(mt, not_empty(mn));
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-	}
-
-	total = 64;
-	mas_set_alloc_req(&mas, total); /* request 2 more. */
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != total);
-	mas_set_err(&mas, -ENOMEM);
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-	for (i = total; i > 0; i--) {
-		unsigned int e = 0; /* expected node_count */
-
-		if (!MAPLE_32BIT) {
-			if (i >= 35)
-				e = i - 34;
-			else if (i >= 5)
-				e = i - 4;
-			else if (i >= 2)
-				e = i - 1;
-		} else {
-			if (i >= 4)
-				e = i - 3;
-			else if (i >= 1)
-				e = i - 1;
-			else
-				e = 0;
-		}
-
-		MT_BUG_ON(mt, mas.alloc->node_count != e);
-		mn = mas_pop_node(&mas);
-		MT_BUG_ON(mt, not_empty(mn));
-		MT_BUG_ON(mt, mas_allocated(&mas) != i - 1);
-		MT_BUG_ON(mt, !mn);
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-	}
-
-	total = 100;
-	for (i = 1; i < total; i++) {
-		mas_set_alloc_req(&mas, i);
-		mas_set_err(&mas, -ENOMEM);
-		MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-		for (j = i; j > 0; j--) {
-			mn = mas_pop_node(&mas);
-			MT_BUG_ON(mt, mas_allocated(&mas) != j - 1);
-			MT_BUG_ON(mt, !mn);
-			MT_BUG_ON(mt, not_empty(mn));
-			mas_push_node(&mas, mn);
-			MT_BUG_ON(mt, mas_allocated(&mas) != j);
-			mn = mas_pop_node(&mas);
-			MT_BUG_ON(mt, not_empty(mn));
-			MT_BUG_ON(mt, mas_allocated(&mas) != j - 1);
-			mn->parent = ma_parent_ptr(mn);
-			ma_free_rcu(mn);
-		}
-		MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-
-		mas_set_alloc_req(&mas, i);
-		mas_set_err(&mas, -ENOMEM);
-		MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-		for (j = 0; j <= i/2; j++) {
-			MT_BUG_ON(mt, mas_allocated(&mas) != i - j);
-			nodes[j] = mas_pop_node(&mas);
-			MT_BUG_ON(mt, mas_allocated(&mas) != i - j - 1);
-		}
-
-		while (j) {
-			j--;
-			mas_push_node(&mas, nodes[j]);
-			MT_BUG_ON(mt, mas_allocated(&mas) != i - j);
-		}
-		MT_BUG_ON(mt, mas_allocated(&mas) != i);
-		for (j = 0; j <= i/2; j++) {
-			MT_BUG_ON(mt, mas_allocated(&mas) != i - j);
-			mn = mas_pop_node(&mas);
-			MT_BUG_ON(mt, not_empty(mn));
-			mn->parent = ma_parent_ptr(mn);
-			ma_free_rcu(mn);
-			MT_BUG_ON(mt, mas_allocated(&mas) != i - j - 1);
-		}
-		mas_reset(&mas);
-		MT_BUG_ON(mt, mas_nomem(&mas, GFP_KERNEL));
-		mas_destroy(&mas);
-
-	}
-
-	/* Set allocation request. */
-	total = 500;
-	mas_node_count(&mas, total);
-	/* Drop the lock and allocate the nodes. */
-	mas_nomem(&mas, GFP_KERNEL);
-	MT_BUG_ON(mt, !mas.alloc);
-	i = 1;
-	smn = mas.alloc;
-	while (i < total) {
-		for (j = 0; j < MAPLE_ALLOC_SLOTS; j++) {
-			i++;
-			MT_BUG_ON(mt, !smn->slot[j]);
-			if (i == total)
-				break;
-		}
-		smn = smn->slot[0]; /* next. */
-	}
-	MT_BUG_ON(mt, mas_allocated(&mas) != total);
-	mas_reset(&mas);
-	mas_destroy(&mas); /* Free. */
-
-	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-	for (i = 1; i < 128; i++) {
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		MT_BUG_ON(mt, mas_allocated(&mas) != i); /* check request filled */
-		for (j = i; j > 0; j--) { /*Free the requests */
-			mn = mas_pop_node(&mas); /* get the next node. */
-			MT_BUG_ON(mt, mn == NULL);
-			MT_BUG_ON(mt, not_empty(mn));
-			mn->parent = ma_parent_ptr(mn);
-			ma_free_rcu(mn);
-		}
-		MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-	}
-
-	for (i = 1; i < MAPLE_NODE_MASK + 1; i++) {
-		MA_STATE(mas2, mt, 0, 0);
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		MT_BUG_ON(mt, mas_allocated(&mas) != i); /* check request filled */
-		for (j = 1; j <= i; j++) { /* Move the allocations to mas2 */
-			mn = mas_pop_node(&mas); /* get the next node. */
-			MT_BUG_ON(mt, mn == NULL);
-			MT_BUG_ON(mt, not_empty(mn));
-			mas_push_node(&mas2, mn);
-			MT_BUG_ON(mt, mas_allocated(&mas2) != j);
-		}
-		MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-		MT_BUG_ON(mt, mas_allocated(&mas2) != i);
-
-		for (j = i; j > 0; j--) { /*Free the requests */
-			MT_BUG_ON(mt, mas_allocated(&mas2) != j);
-			mn = mas_pop_node(&mas2); /* get the next node. */
-			MT_BUG_ON(mt, mn == NULL);
-			MT_BUG_ON(mt, not_empty(mn));
-			mn->parent = ma_parent_ptr(mn);
-			ma_free_rcu(mn);
-		}
-		MT_BUG_ON(mt, mas_allocated(&mas2) != 0);
-	}
-
-
-	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS + 1); /* Request */
-	MT_BUG_ON(mt, mas.node != MA_ERROR(-ENOMEM));
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 1);
-	MT_BUG_ON(mt, mas.alloc->node_count != MAPLE_ALLOC_SLOTS);
-
-	mn = mas_pop_node(&mas); /* get the next node. */
-	MT_BUG_ON(mt, mn == NULL);
-	MT_BUG_ON(mt, not_empty(mn));
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS);
-	MT_BUG_ON(mt, mas.alloc->node_count != MAPLE_ALLOC_SLOTS - 1);
-
-	mas_push_node(&mas, mn);
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 1);
-	MT_BUG_ON(mt, mas.alloc->node_count != MAPLE_ALLOC_SLOTS);
-
-	/* Check the limit of pop/push/pop */
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS + 2); /* Request */
-	MT_BUG_ON(mt, mas_alloc_req(&mas) != 1);
-	MT_BUG_ON(mt, mas.node != MA_ERROR(-ENOMEM));
-	MT_BUG_ON(mt, !mas_nomem(&mas, GFP_KERNEL));
-	MT_BUG_ON(mt, mas_alloc_req(&mas));
-	MT_BUG_ON(mt, mas.alloc->node_count != 1);
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 2);
-	mn = mas_pop_node(&mas);
-	MT_BUG_ON(mt, not_empty(mn));
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 1);
-	MT_BUG_ON(mt, mas.alloc->node_count  != MAPLE_ALLOC_SLOTS);
-	mas_push_node(&mas, mn);
-	MT_BUG_ON(mt, mas.alloc->node_count != 1);
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 2);
-	mn = mas_pop_node(&mas);
-	MT_BUG_ON(mt, not_empty(mn));
-	mn->parent = ma_parent_ptr(mn);
-	ma_free_rcu(mn);
-	for (i = 1; i <= MAPLE_ALLOC_SLOTS + 1; i++) {
-		mn = mas_pop_node(&mas);
-		MT_BUG_ON(mt, not_empty(mn));
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-	}
-	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
-
-
-	for (i = 3; i < MAPLE_NODE_MASK * 3; i++) {
-		mas.node = MA_ERROR(-ENOMEM);
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mas_push_node(&mas, mn); /* put it back */
-		mas_destroy(&mas);
-
-		mas.node = MA_ERROR(-ENOMEM);
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mn2 = mas_pop_node(&mas); /* get the next node. */
-		mas_push_node(&mas, mn); /* put them back */
-		mas_push_node(&mas, mn2);
-		mas_destroy(&mas);
-
-		mas.node = MA_ERROR(-ENOMEM);
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mn2 = mas_pop_node(&mas); /* get the next node. */
-		mn3 = mas_pop_node(&mas); /* get the next node. */
-		mas_push_node(&mas, mn); /* put them back */
-		mas_push_node(&mas, mn2);
-		mas_push_node(&mas, mn3);
-		mas_destroy(&mas);
-
-		mas.node = MA_ERROR(-ENOMEM);
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-		mas_destroy(&mas);
-
-		mas.node = MA_ERROR(-ENOMEM);
-		mas_node_count(&mas, i); /* Request */
-		mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-		mn = mas_pop_node(&mas); /* get the next node. */
-		mn->parent = ma_parent_ptr(mn);
-		ma_free_rcu(mn);
-		mas_destroy(&mas);
-	}
-
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, 5); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	MT_BUG_ON(mt, mas_allocated(&mas) != 5);
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, 10); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	mas.status = ma_start;
-	MT_BUG_ON(mt, mas_allocated(&mas) != 10);
-	mas_destroy(&mas);
-
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS - 1); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS - 1);
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, 10 + MAPLE_ALLOC_SLOTS - 1); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	mas.status = ma_start;
-	MT_BUG_ON(mt, mas_allocated(&mas) != 10 + MAPLE_ALLOC_SLOTS - 1);
-	mas_destroy(&mas);
-
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS + 1); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 1);
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS * 2 + 2); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	mas.status = ma_start;
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS * 2 + 2);
-	mas_destroy(&mas);
-
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS * 2 + 1); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS * 2 + 1);
-	mas.node = MA_ERROR(-ENOMEM);
-	mas_node_count(&mas, MAPLE_ALLOC_SLOTS * 3 + 2); /* Request */
-	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
-	mas.status = ma_start;
-	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS * 3 + 2);
-	mas_destroy(&mas);
-
-	mtree_unlock(mt);
-}
-
 /*
  * Check erasing including RCU.
  */
@@ -35455,17 +35025,6 @@ static void check_dfs_preorder(struct maple_tree *mt)
 	MT_BUG_ON(mt, count != e);
 	mtree_destroy(mt);
 
-	mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
-	mas_reset(&mas);
-	mt_zero_nr_tallocated();
-	mt_set_non_kernel(200);
-	mas_expected_entries(&mas, max);
-	for (count = 0; count <= max; count++) {
-		mas.index = mas.last = count;
-		mas_store(&mas, xa_mk_value(count));
-		MT_BUG_ON(mt, mas_is_err(&mas));
-	}
-	mas_destroy(&mas);
 	rcu_barrier();
 	/*
 	 * pr_info(" ->seq test of 0-%lu %luK in %d active (%d total)\n",
@@ -35524,6 +35083,18 @@ static unsigned char get_vacant_height(struct ma_wr_state *wr_mas, void *entry)
 	return vacant_height;
 }
 
+static int mas_allocated(struct ma_state *mas)
+{
+	int total = 0;
+
+	if (mas->alloc)
+		total++;
+
+	if (mas->sheaf)
+		total += kmem_cache_sheaf_size(mas->sheaf);
+
+	return total;
+}
 /* Preallocation testing */
 static noinline void __init check_prealloc(struct maple_tree *mt)
 {
@@ -35542,7 +35113,10 @@ static noinline void __init check_prealloc(struct maple_tree *mt)
 
 	/* Spanning store */
 	mas_set_range(&mas, 470, 500);
-	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
+
+	mas_wr_preallocate(&wr_mas, ptr);
+	MT_BUG_ON(mt, mas.store_type != wr_spanning_store);
+	MT_BUG_ON(mt, mas_is_err(&mas));
 	allocated = mas_allocated(&mas);
 	height = mas_mt_height(&mas);
 	vacant_height = get_vacant_height(&wr_mas, ptr);
@@ -35552,6 +35126,7 @@ static noinline void __init check_prealloc(struct maple_tree *mt)
 	allocated = mas_allocated(&mas);
 	MT_BUG_ON(mt, allocated != 0);
 
+	mas_wr_preallocate(&wr_mas, ptr);
 	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
 	allocated = mas_allocated(&mas);
 	height = mas_mt_height(&mas);
@@ -35597,20 +35172,6 @@ static noinline void __init check_prealloc(struct maple_tree *mt)
 	height = mas_mt_height(&mas);
 	vacant_height = get_vacant_height(&wr_mas, ptr);
 	MT_BUG_ON(mt, allocated != 1 + (height - vacant_height) * 3);
-	mn = mas_pop_node(&mas);
-	MT_BUG_ON(mt, mas_allocated(&mas) != allocated - 1);
-	mas_push_node(&mas, mn);
-	MT_BUG_ON(mt, mas_allocated(&mas) != allocated);
-	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
-	mas_destroy(&mas);
-	allocated = mas_allocated(&mas);
-	MT_BUG_ON(mt, allocated != 0);
-
-	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
-	allocated = mas_allocated(&mas);
-	height = mas_mt_height(&mas);
-	vacant_height = get_vacant_height(&wr_mas, ptr);
-	MT_BUG_ON(mt, allocated != 1 + (height - vacant_height) * 3);
 	mas_store_prealloc(&mas, ptr);
 	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
 
@@ -36406,11 +35967,17 @@ static void check_nomem_writer_race(struct maple_tree *mt)
 	check_load(mt, 6, xa_mk_value(0xC));
 	mtree_unlock(mt);
 
+	mt_set_non_kernel(0);
 	/* test for the same race but with mas_store_gfp() */
 	mtree_store_range(mt, 0, 5, xa_mk_value(0xA), GFP_KERNEL);
 	mtree_store_range(mt, 6, 10, NULL, GFP_KERNEL);
 
 	mas_set_range(&mas, 0, 5);
+
+	/* setup writer 2 that will trigger the race condition */
+	mt_set_private(mt);
+	mt_set_callback(writer2);
+
 	mtree_lock(mt);
 	mas_store_gfp(&mas, NULL, GFP_KERNEL);
 
@@ -36454,27 +36021,6 @@ static inline int check_vma_modification(struct maple_tree *mt)
 	return 0;
 }
 
-/*
- * test to check that bulk stores do not use wr_rebalance as the store
- * type.
- */
-static inline void check_bulk_rebalance(struct maple_tree *mt)
-{
-	MA_STATE(mas, mt, ULONG_MAX, ULONG_MAX);
-	int max = 10;
-
-	build_full_tree(mt, 0, 2);
-
-	/* erase every entry in the tree */
-	do {
-		/* set up bulk store mode */
-		mas_expected_entries(&mas, max);
-		mas_erase(&mas);
-		MT_BUG_ON(mt, mas.store_type == wr_rebalance);
-	} while (mas_prev(&mas, 0) != NULL);
-
-	mas_destroy(&mas);
-}
 
 void farmer_tests(void)
 {
@@ -36487,10 +36033,6 @@ void farmer_tests(void)
 	check_vma_modification(&tree);
 	mtree_destroy(&tree);
 
-	mt_init(&tree);
-	check_bulk_rebalance(&tree);
-	mtree_destroy(&tree);
-
 	tree.ma_root = xa_mk_value(0);
 	mt_dump(&tree, mt_dump_dec);
 
@@ -36550,10 +36092,6 @@ void farmer_tests(void)
 	check_erase_testset(&tree);
 	mtree_destroy(&tree);
 
-	mt_init_flags(&tree, 0);
-	check_new_node(&tree);
-	mtree_destroy(&tree);
-
 	if (!MAPLE_32BIT) {
 		mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
 		check_rcu_simulated(&tree);