Merge tag 'slab-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab updates from Vlastimil Babka:
 "The main change is naturally the SLOB removal. Since its deprecation
  in 6.2 I've seen no complaints so hopefully SLUB_(TINY) works well for
  everyone and we can proceed.

  Besides the code cleanup, the main immediate benefit will be allowing
  kfree() family of function to work on kmem_cache_alloc() objects,
  which was incompatible with SLOB. This includes kfree_rcu() which had
  no kmem_cache_free_rcu() counterpart yet and now it shouldn't be
  necessary anymore.

  Besides that, there are several small code and comment improvements
  from Thomas, Thorsten and Vernon"

* tag 'slab-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  mm/slab: document kfree() as allowed for kmem_cache_alloc() objects
  mm/slob: remove slob.c
  mm/slab: remove CONFIG_SLOB code from slab common code
  mm, pagemap: remove SLOB and SLQB from comments and documentation
  mm, page_flags: remove PG_slob_free
  mm/slob: remove CONFIG_SLOB
  mm/slub: fix help comment of SLUB_DEBUG
  mm: slub: make kobj_type structure constant
  slab: Adjust comment after refactoring of gfp.h

3 files changed, 5 insertions, 46 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index a7e3a3405520..2bdc41cb0594 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -174,9 +174,6 @@ enum pageflags {
 	/* Remapped by swiotlb-xen. */
 	PG_xen_remapped = PG_owner_priv_1,
 
-	/* SLOB */
-	PG_slob_free = PG_private,
-
 #ifdef CONFIG_MEMORY_FAILURE
 	/*
 	 * Compound pages. Stored in first tail page's flags.
@@ -483,7 +480,6 @@ PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
 PAGEFLAG(Workingset, workingset, PF_HEAD)
 	TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
-__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
 PAGEFLAG(Checked, checked, PF_NO_COMPOUND)	   /* Used by some filesystems */
 
 /* Xen */
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 094321c17e48..dcd2cf1e8326 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -976,8 +976,10 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  * either fall back to use of call_rcu() or rearrange the structure to
  * position the rcu_head structure into the first 4096 bytes.
  *
- * Note that the allowable offset might decrease in the future, for example,
- * to allow something like kmem_cache_free_rcu().
+ * The object to be freed can be allocated either by kmalloc() or
+ * kmem_cache_alloc().
+ *
+ * Note that the allowable offset might decrease in the future.
  *
  * The BUILD_BUG_ON check must not involve any function calls, hence the
  * checks are done in macros here.
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 45af70315a94..7db48f9f0d9d 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -298,19 +298,6 @@ static inline unsigned int arch_slab_minalign(void)
 #endif
 #endif
 
-#ifdef CONFIG_SLOB
-/*
- * SLOB passes all requests larger than one page to the page allocator.
- * No kmalloc array is necessary since objects of different sizes can
- * be allocated from the same page.
- */
-#define KMALLOC_SHIFT_HIGH	PAGE_SHIFT
-#define KMALLOC_SHIFT_MAX	(MAX_ORDER + PAGE_SHIFT - 1)
-#ifndef KMALLOC_SHIFT_LOW
-#define KMALLOC_SHIFT_LOW	3
-#endif
-#endif
-
 /* Maximum allocatable size */
 #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_MAX)
 /* Maximum size for which we actually use a slab cache */
@@ -366,7 +353,6 @@ enum kmalloc_cache_type {
 	NR_KMALLOC_TYPES
 };
 
-#ifndef CONFIG_SLOB
 extern struct kmem_cache *
 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
 
@@ -458,7 +444,6 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
 }
 static_assert(PAGE_SHIFT <= 20);
 #define kmalloc_index(s) __kmalloc_index(s, true)
-#endif /* !CONFIG_SLOB */
 
 void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
 
@@ -487,10 +472,6 @@ void kmem_cache_free(struct kmem_cache *s, void *objp);
 void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p);
 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p);
 
-/*
- * Caller must not use kfree_bulk() on memory not originally allocated
- * by kmalloc(), because the SLOB allocator cannot handle this.
- */
 static __always_inline void kfree_bulk(size_t size, void **p)
 {
 	kmem_cache_free_bulk(NULL, size, p);
@@ -526,7 +507,7 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align
  * to be at least to the size.
  *
  * The @flags argument may be one of the GFP flags defined at
- * include/linux/gfp.h and described at
+ * include/linux/gfp_types.h and described at
  * :ref:`Documentation/core-api/mm-api.rst <mm-api-gfp-flags>`
  *
  * The recommended usage of the @flags is described at
@@ -567,7 +548,6 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align
  *	Try really hard to succeed the allocation but fail
  *	eventually.
  */
-#ifndef CONFIG_SLOB
 static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
 {
 	if (__builtin_constant_p(size) && size) {
@@ -583,17 +563,7 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
 	}
 	return __kmalloc(size, flags);
 }
-#else
-static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
-{
-	if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
-		return kmalloc_large(size, flags);
-
-	return __kmalloc(size, flags);
-}
-#endif
 
-#ifndef CONFIG_SLOB
 static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	if (__builtin_constant_p(size) && size) {
@@ -609,15 +579,6 @@ static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t fla
 	}
 	return __kmalloc_node(size, flags, node);
 }
-#else
-static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
-{
-	if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
-		return kmalloc_large_node(size, flags, node);
-
-	return __kmalloc_node(size, flags, node);
-}
-#endif
 
 /**
  * kmalloc_array - allocate memory for an array.