[PATCH v3 15/15] mm/slab: replace __GFP_NO_OBJ_EXT with SLAB_ALLOC_NO_RECURSE for sheaves

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

Finish the switch away from __GFP_NO_OBJ_EXT by replacing it with
SLAB_ALLOC_NO_RECURSE when allocating empty sheaves. Pass alloc_flags to
[__]alloc_empty_sheaf(). Callers that can't be part of a recursive
kmalloc() chain simply pass SLAB_ALLOC_DEFAULT. Use kmalloc_flags()
instead of kzalloc() for allocating the sheaf.

With that we can finalize the removal the __GFP_NO_OBJ_EXT handling from
obj_ext allocations as well, leaving only SLAB_ALLOC_NO_RECURSE in
place.

This leaves __GFP_NO_OBJ_EXT with no users in slab, so stop allowing the
flag in kmalloc_nolock().

Link: https://patch.msgid.link/20260610-slab_alloc_flags-v2-16-7190909db118@kernel.org
Reviewed-by: Hao Li <hao.li@linux.dev>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
---
 include/linux/slab.h |  6 +++---
 mm/slub.c            | 34 +++++++++++++++++-----------------
 2 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index b955f3cbb732..43c3d9b51107 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -1039,9 +1039,9 @@ void *_kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_flags, in
 /**
  * kmalloc_nolock - Allocate an object of given size from any context.
  * @size: size to allocate
- * @gfp_flags: GFP flags. Only __GFP_ACCOUNT, __GFP_ZERO, __GFP_NO_OBJ_EXT
- * allowed. Also __GFP_NOWARN and __GFP_NOMEMALLOC are allowed but added
- * internally thus not necessary.
+ * @gfp_flags: GFP flags. Only __GFP_ACCOUNT and __GFP_ZERO allowed.  Also
+ * __GFP_NOWARN and __GFP_NOMEMALLOC are allowed but added internally thus not
+ * necessary.
  * @node: node number of the target node.
  *
  * Return: pointer to the new object or NULL in case of error.
diff --git a/mm/slub.c b/mm/slub.c
index fc5b8c85b690..62e9cd46916f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2171,7 +2171,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
 
 	gfp &= ~OBJCGS_CLEAR_MASK;
 	/* Prevent recursive extension vector allocation */
-	gfp |= __GFP_NO_OBJ_EXT;
 	alloc_flags |= SLAB_ALLOC_NO_RECURSE;
 
 	sz = obj_exts_alloc_size(s, slab, gfp);
@@ -2376,7 +2375,7 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags,
 	if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE))
 		return;
 
-	if (alloc_flags & SLAB_ALLOC_NO_RECURSE || flags & __GFP_NO_OBJ_EXT)
+	if (alloc_flags & SLAB_ALLOC_NO_RECURSE)
 		return;
 
 	slab = virt_to_slab(object);
@@ -2761,7 +2760,7 @@ static inline void *setup_object(struct kmem_cache *s, void *object)
 }
 
 static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
-					      unsigned int capacity)
+				unsigned int alloc_flags, unsigned int capacity)
 {
 	struct slab_sheaf *sheaf;
 	size_t sheaf_size;
@@ -2772,10 +2771,10 @@ static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
 	 * bucket)
 	 */
 	if (s->flags & SLAB_KMALLOC)
-		gfp |= __GFP_NO_OBJ_EXT;
+		alloc_flags |= SLAB_ALLOC_NO_RECURSE;
 
 	sheaf_size = struct_size(sheaf, objects, capacity);
-	sheaf = kzalloc(sheaf_size, gfp);
+	sheaf = kmalloc_flags(sheaf_size, gfp | __GFP_ZERO, alloc_flags, NUMA_NO_NODE);
 
 	if (unlikely(!sheaf))
 		return NULL;
@@ -2788,20 +2787,20 @@ static struct slab_sheaf *__alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp,
 }
 
 static inline struct slab_sheaf *alloc_empty_sheaf(struct kmem_cache *s,
-						   gfp_t gfp)
+				gfp_t gfp, unsigned int alloc_flags)
 {
-	if (gfp & __GFP_NO_OBJ_EXT)
+	if (alloc_flags & SLAB_ALLOC_NO_RECURSE)
 		return NULL;
 
 	gfp &= ~OBJCGS_CLEAR_MASK;
 
-	return __alloc_empty_sheaf(s, gfp, s->sheaf_capacity);
+	return __alloc_empty_sheaf(s, gfp, alloc_flags, s->sheaf_capacity);
 }
 
 static void free_empty_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf)
 {
 	/*
-	 * If the sheaf was created with __GFP_NO_OBJ_EXT flag then its
+	 * If the sheaf was created with SLAB_ALLOC_NO_RECURSE flag then its
 	 * corresponding extension is NULL and alloc_tag_sub() will throw a
 	 * warning, therefore replace NULL with CODETAG_EMPTY to indicate
 	 * that the extension for this sheaf is expected to be NULL.
@@ -4693,7 +4692,7 @@ __pcs_replace_empty_main(struct kmem_cache *s, struct slub_percpu_sheaves *pcs,
 		return NULL;
 
 	if (!empty) {
-		empty = alloc_empty_sheaf(s, gfp);
+		empty = alloc_empty_sheaf(s, gfp, alloc_flags);
 		if (!empty)
 			return NULL;
 	}
@@ -5066,7 +5065,7 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
 
 	if (unlikely(size > s->sheaf_capacity)) {
 
-		sheaf = __alloc_empty_sheaf(s, gfp, size);
+		sheaf = __alloc_empty_sheaf(s, gfp, SLAB_ALLOC_DEFAULT, size);
 		if (!sheaf)
 			return NULL;
 
@@ -5111,7 +5110,7 @@ kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
 
 
 	if (!sheaf)
-		sheaf = alloc_empty_sheaf(s, gfp);
+		sheaf = alloc_empty_sheaf(s, gfp, SLAB_ALLOC_DEFAULT);
 
 	if (sheaf) {
 		sheaf->capacity = s->sheaf_capacity;
@@ -5396,7 +5395,7 @@ static void *__kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_f
 
 	VM_WARN_ON_ONCE(alloc_flags_allow_spinning(ac->alloc_flags));
 	VM_WARN_ON_ONCE(gfp_flags & ~(__GFP_ACCOUNT | __GFP_ZERO |
-			__GFP_NO_OBJ_EXT | __GFP_NOWARN | __GFP_NOMEMALLOC));
+				      __GFP_NOWARN | __GFP_NOMEMALLOC));
 
 	gfp_flags |= __GFP_NOWARN | __GFP_NOMEMALLOC;
 
@@ -5911,7 +5910,7 @@ __pcs_replace_full_main(struct kmem_cache *s, struct slub_percpu_sheaves *pcs,
 	if (!allow_spin)
 		return NULL;
 
-	empty = alloc_empty_sheaf(s, GFP_NOWAIT);
+	empty = alloc_empty_sheaf(s, GFP_NOWAIT, SLAB_ALLOC_DEFAULT);
 	if (empty)
 		goto got_empty;
 
@@ -6095,7 +6094,7 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj)
 
 		local_unlock(&s->cpu_sheaves->lock);
 
-		empty = alloc_empty_sheaf(s, GFP_NOWAIT);
+		empty = alloc_empty_sheaf(s, GFP_NOWAIT, SLAB_ALLOC_DEFAULT);
 
 		if (!empty)
 			goto fail;
@@ -7640,7 +7639,7 @@ static int init_percpu_sheaves(struct kmem_cache *s)
 		if (!s->sheaf_capacity)
 			pcs->main = &bootstrap_sheaf;
 		else
-			pcs->main = alloc_empty_sheaf(s, GFP_KERNEL);
+			pcs->main = alloc_empty_sheaf(s, GFP_KERNEL, SLAB_ALLOC_DEFAULT);
 
 		if (!pcs->main)
 			return -ENOMEM;
@@ -8506,7 +8505,8 @@ static void __init bootstrap_cache_sheaves(struct kmem_cache *s)
 
 		pcs = per_cpu_ptr(s->cpu_sheaves, cpu);
 
-		pcs->main = __alloc_empty_sheaf(s, GFP_KERNEL, capacity);
+		pcs->main = __alloc_empty_sheaf(s, GFP_KERNEL,
+				SLAB_ALLOC_DEFAULT, capacity);
 
 		if (!pcs->main) {
 			failed = true;

-- 
2.54.0