mm/slab: decouple SLAB_NO_SHEAVES from SLAB_NO_OBJ_EXT

Bootstrap caches are created with SLAB_NO_OBJ_EXT to disallow sheaves
and obj_exts.

To allow disabling obj_exts while allowing sheaves, decouple
SLAB_NO_SHEAVES from SLAB_NO_OBJ_EXT. Bootstrap caches now have both
SLAB_NO_SHEAVES and SLAB_NO_OBJ_EXT.

No functional change intended.

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Link: https://patch.msgid.link/20260713-kmalloc-no-objext-v3-2-47c7bd138de7@kernel.org
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 51f03f18c9a7b41d0b618a043fa4886055c9dec7..08d7b6c9c4d699ea870b6d0a12517e61f9aa7f95 100644 (file)
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -58,10 +58,13 @@ enum _slab_flag_bits {
 #endif
        _SLAB_OBJECT_POISON,
        _SLAB_CMPXCHG_DOUBLE,
+#ifdef CONFIG_SLAB_OBJ_EXT
        _SLAB_NO_OBJ_EXT,
-#if defined(CONFIG_SLAB_OBJ_EXT) && defined(CONFIG_64BIT)
+#ifdef CONFIG_64BIT
        _SLAB_OBJ_EXT_IN_OBJ,
 #endif
+#endif
+       _SLAB_NO_SHEAVES,
        _SLAB_FLAGS_LAST_BIT
 };
 
@@ -239,8 +242,14 @@ enum _slab_flag_bits {
 #endif
 #define SLAB_TEMPORARY         SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
 
-/* Slab created using create_boot_cache */
+/* Slab caches without obj_exts array */
+#ifdef CONFIG_SLAB_OBJ_EXT
 #define SLAB_NO_OBJ_EXT                __SLAB_FLAG_BIT(_SLAB_NO_OBJ_EXT)
+#else
+#define SLAB_NO_OBJ_EXT                __SLAB_FLAG_UNUSED
+#endif
+
+#define SLAB_NO_SHEAVES                __SLAB_FLAG_BIT(_SLAB_NO_SHEAVES)
 
 #if defined(CONFIG_SLAB_OBJ_EXT) && defined(CONFIG_64BIT)
 #define SLAB_OBJ_EXT_IN_OBJ    __SLAB_FLAG_BIT(_SLAB_OBJ_EXT_IN_OBJ)

diff --git a/mm/slub.c b/mm/slub.c
index f9461a0c47d31b9fb59bffe36110fab8abd38be2..abe748b7dddbb9a92c84d524a34d42243553a345 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -7799,12 +7799,12 @@ static unsigned int calculate_sheaf_capacity(struct kmem_cache *s,
                return 0;
 
        /*
-        * Bootstrap caches can't have sheaves for now (SLAB_NO_OBJ_EXT).
+        * Bootstrap caches can't have sheaves for now (SLAB_NO_SHEAVES).
         * SLAB_NOLEAKTRACE caches (e.g., kmemleak's object_cache) must not
         * have sheaves to avoid recursion when sheaf allocation triggers
         * kmemleak tracking.
         */
-       if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE))
+       if (s->flags & (SLAB_NO_SHEAVES | SLAB_NOLEAKTRACE))
                return 0;
 
        /*
@@ -8586,7 +8586,8 @@ void __init kmem_cache_init(void)
 
        create_boot_cache(kmem_cache_node, "kmem_cache_node",
                        sizeof(struct kmem_cache_node),
-                       SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0);
+                       SLAB_HWCACHE_ALIGN | SLAB_NO_SHEAVES | SLAB_NO_OBJ_EXT,
+                       0, 0);
 
        hotplug_node_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
 
@@ -8596,7 +8597,8 @@ void __init kmem_cache_init(void)
        create_boot_cache(kmem_cache, "kmem_cache",
                        offsetof(struct kmem_cache, per_node) +
                                nr_node_ids * sizeof(struct kmem_cache_per_node_ptrs),
-                       SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0);
+                       SLAB_HWCACHE_ALIGN | SLAB_NO_SHEAVES | SLAB_NO_OBJ_EXT,
+                       0, 0);
 
        kmem_cache = bootstrap(&boot_kmem_cache);
        kmem_cache_node = bootstrap(&boot_kmem_cache_node);