[RFC PATCH 14/30] mm: prevent slabobj_ext allocations for slabobj_ext and kmem_cache objects

Suren Baghdasaryan
2022-08-30T21:52:10Z

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/memcontrol.c | 2 ++
mm/slab.h | 6 ++++++
2 files changed, 8 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3f407ef2f3f1..dabb451dc364 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2809,6 +2809,8 @@ 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)
diff --git a/mm/slab.h b/mm/slab.h
index c767ce3f0fe2..d93b22b8bbe2 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -475,6 +475,12 @@ static inline void prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags,
if (is_kmem_only_obj_ext())
return;

+ if (s->flags & SLAB_NO_OBJ_EXT)
+ return;
+
+ if (flags & __GFP_NO_OBJ_EXT)
+ return;
+
slab = virt_to_slab(p);
if (!slab_obj_exts(slab))
WARN(alloc_slab_obj_exts(slab, s, flags, false),
--
2.37.2.672.g94769d06f0-goog