[PATCH v3 08/35] mm: prevent slabobj_ext allocations for slabobj_ext and kmem_cache objects

Suren Baghdasaryan
2024-02-12T21:39:50Z

Use __GFP_NO_OBJ_EXT to prevent recursions when allocating slabobj_ext
objects. Also prevent slabobj_ext allocations for kmem_cache objects.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
mm/slab.h | 6 ++++++
mm/slab_common.c | 2 ++
2 files changed, 8 insertions(+)

diff --git a/mm/slab.h b/mm/slab.h
index 436a126486b5..f4ff635091e4 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -589,6 +589,12 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p)
if (!need_slab_obj_ext())
return NULL;

+ if (s->flags & SLAB_NO_OBJ_EXT)
+ return NULL;
+
+ if (flags & __GFP_NO_OBJ_EXT)
+ return NULL;
+
slab = virt_to_slab(p);
if (!slab_obj_exts(slab) &&
WARN(alloc_slab_obj_exts(slab, s, flags, false),
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 6bfa1810da5e..83fec2dd2e2d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -218,6 +218,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
void *vec;

gfp &= ~OBJCGS_CLEAR_MASK;
+ /* Prevent recursive extension vector allocation */
+ gfp |= __GFP_NO_OBJ_EXT;
vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp,
slab_nid(slab));
if (!vec)
--
2.43.0.687.g38aa6559b0-goog