mm/slab: introduce SLAB_NO_OBJ_EXT to avoid obj_ext creation

Slab extension objects can't be allocated before slab infrastructure is
initialized.  Some caches, like kmem_cache and kmem_cache_node, are
created before slab infrastructure is initialized.  Objects from these
caches can't have extension objects.  Introduce SLAB_NO_OBJ_EXT slab flag
to mark these caches and avoid creating extensions for objects allocated
from these slabs.

Link: https://lkml.kernel.org/r/20240321163705.3067592-9-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/slab.h b/include/linux/slab.h
index e53cbfa18325587fdf1363cae60066a11959c7df..68ff754b85a4ae447601621cd7ae87763bd1c864 100644 (file)
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -56,6 +56,9 @@ enum _slab_flag_bits {
 #endif
        _SLAB_OBJECT_POISON,
        _SLAB_CMPXCHG_DOUBLE,
+#ifdef CONFIG_SLAB_OBJ_EXT
+       _SLAB_NO_OBJ_EXT,
+#endif
        _SLAB_FLAGS_LAST_BIT
 };
 
@@ -202,6 +205,13 @@ enum _slab_flag_bits {
 #endif
 #define SLAB_TEMPORARY         SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
 
+/* Slab created using create_boot_cache */
+#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
+
 /*
  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
  *

diff --git a/mm/slub.c b/mm/slub.c
index 2cb53642a091e0fe11b6cfd8fbb92841c77750a4..666dcc3b8a26881d48b192a443c71bcf01ec34e1 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5693,7 +5693,8 @@ void __init kmem_cache_init(void)
                node_set(node, slab_nodes);
 
        create_boot_cache(kmem_cache_node, "kmem_cache_node",
-               sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0);
+                       sizeof(struct kmem_cache_node),
+                       SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0);
 
        hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
 
@@ -5703,7 +5704,7 @@ void __init kmem_cache_init(void)
        create_boot_cache(kmem_cache, "kmem_cache",
                        offsetof(struct kmem_cache, node) +
                                nr_node_ids * sizeof(struct kmem_cache_node *),
-                      SLAB_HWCACHE_ALIGN, 0, 0);
+                       SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0);
 
        kmem_cache = bootstrap(&boot_kmem_cache);
        kmem_cache_node = bootstrap(&boot_kmem_cache_node);