alloc_empty_sheaf() allocates sheaves from SLAB_KMALLOC caches using __GFP_NO_OBJ_EXT to avoid recursion, however it does not mark their allocation tags empty before freeing, which results in a warning when CONFIG_MEM_ALLOC_PROFILING_DEBUG is set. Fix this by marking allocation tags for such sheaves as empty. Reported-by: David Wang <00107082@163.com> Closes: https://lore.kernel.org/all/20260223155128.3849-1-00107082@163.com/ Analyzed-by: Harry Yoo Signed-off-by: Suren Baghdasaryan Reviewed-by: Harry Yoo Tested-by: Harry Yoo Tested-by: David Wang <00107082@163.com> --- include/linux/gfp_types.h | 2 ++ mm/slab.h | 4 ++-- mm/slub.c | 33 +++++++++++++++++++++++---------- 3 files changed, 27 insertions(+), 12 deletions(-) diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h index 814bb2892f99..6c75df30a281 100644 --- a/include/linux/gfp_types.h +++ b/include/linux/gfp_types.h @@ -139,6 +139,8 @@ enum { * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg. * * %__GFP_NO_OBJ_EXT causes slab allocation to have no object extension. + * mark_obj_codetag_empty() should be called upon freeing for objects allocated + * with this flag to indicate that their NULL tags are expected and normal. */ #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) diff --git a/mm/slab.h b/mm/slab.h index 71c7261bf822..f6ef862b60ef 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -290,14 +290,14 @@ static inline void *nearest_obj(struct kmem_cache *cache, /* Determine object index from a given position */ static inline unsigned int __obj_to_index(const struct kmem_cache *cache, - void *addr, void *obj) + void *addr, const void *obj) { return reciprocal_divide(kasan_reset_tag(obj) - addr, cache->reciprocal_size); } static inline unsigned int obj_to_index(const struct kmem_cache *cache, - const struct slab *slab, void *obj) + const struct slab *slab, const void *obj) { if (is_kfence_address(obj)) return 0; diff --git a/mm/slub.c b/mm/slub.c index 862642c165ed..34c32749f091 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2041,18 +2041,18 @@ static inline void dec_slabs_node(struct kmem_cache *s, int node, #ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG -static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) +static inline void mark_obj_codetag_empty(const void *obj) { - struct slab *obj_exts_slab; + struct slab *obj_slab; unsigned long slab_exts; - obj_exts_slab = virt_to_slab(obj_exts); - slab_exts = slab_obj_exts(obj_exts_slab); + obj_slab = virt_to_slab(obj); + slab_exts = slab_obj_exts(obj_slab); if (slab_exts) { get_slab_obj_exts(slab_exts); - unsigned int offs = obj_to_index(obj_exts_slab->slab_cache, - obj_exts_slab, obj_exts); - struct slabobj_ext *ext = slab_obj_ext(obj_exts_slab, + unsigned int offs = obj_to_index(obj_slab->slab_cache, + obj_slab, obj); + struct slabobj_ext *ext = slab_obj_ext(obj_slab, slab_exts, offs); if (unlikely(is_codetag_empty(&ext->ref))) { @@ -2090,7 +2090,7 @@ static inline void handle_failed_objexts_alloc(unsigned long obj_exts, #else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ -static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {} +static inline void mark_obj_codetag_empty(const void *obj) {} static inline bool mark_failed_objexts_alloc(struct slab *slab) { return false; } static inline void handle_failed_objexts_alloc(unsigned long obj_exts, struct slabobj_ext *vec, unsigned int objects) {} @@ -2211,7 +2211,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, * assign slabobj_exts in parallel. In this case the existing * objcg vector should be reused. */ - mark_objexts_empty(vec); + mark_obj_codetag_empty(vec); if (unlikely(!allow_spin)) kfree_nolock(vec); else @@ -2254,7 +2254,7 @@ static inline void free_slab_obj_exts(struct slab *slab, bool allow_spin) * NULL, therefore replace NULL with CODETAG_EMPTY to indicate that * the extension for obj_exts is expected to be NULL. */ - mark_objexts_empty(obj_exts); + mark_obj_codetag_empty(obj_exts); if (allow_spin) kfree(obj_exts); else @@ -2312,6 +2312,10 @@ static void alloc_slab_obj_exts_early(struct kmem_cache *s, struct slab *slab) #else /* CONFIG_SLAB_OBJ_EXT */ +static inline void mark_obj_codetag_empty(const void *obj) +{ +} + static inline void init_slab_obj_exts(struct slab *slab) { } @@ -2783,6 +2787,15 @@ static inline struct slab_sheaf *alloc_empty_sheaf(struct kmem_cache *s, static void free_empty_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf) { + /* + * If the sheaf was created with __GFP_NO_OBJ_EXT flag then its + * corresponding extension is NULL and alloc_tag_sub() will throw a + * warning, therefore replace NULL with CODETAG_EMPTY to indicate + * that the extension for this sheaf is expected to be NULL. + */ + if (s->flags & SLAB_KMALLOC) + mark_obj_codetag_empty(sheaf); + kfree(sheaf); stat(s, SHEAF_FREE); base-commit: 7dff99b354601dd01829e1511711846e04340a69 -- 2.53.0.414.gf7e9f6c205-goog