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mm/slab: abstract slabobj_ext.ref access

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In preparation for changes to the structure, abstract access to the ref
field with a slab_obj_ext_codetag_ref() function. Rename the field to
_ctref to make an unexpected direct access a compile error.

No functional change intended.

Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Hao Li <hao.li@linux.dev>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260727-b4-objext_split-v3-6-c29ef0f1f257@kernel.org
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
This commit is contained in:
Vlastimil Babka (SUSE) 2026-07-27 14:54:00 +02:00
parent 060324c553
commit e684ee3bb5
2 changed files with 37 additions and 15 deletions
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10
mm/slab.h
View File

@ -558,7 +558,7 @@ struct slabobj_ext {
struct obj_cgroup *_objcg;
#endif
#ifdef CONFIG_MEM_ALLOC_PROFILING
union codetag_ref ref;
union codetag_ref _ctref;
#endif
} __aligned(8);
@ -677,6 +677,14 @@ slab_obj_ext_set_objcg(struct slab *slab, struct slabobj_ext *obj_ext,
}
#endif
#ifdef CONFIG_MEM_ALLOC_PROFILING
static inline union codetag_ref *
slab_obj_ext_codetag_ref(struct slab *slab, struct slabobj_ext *obj_ext)
{
return &obj_ext->_ctref;
}
#endif
int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
gfp_t gfp, unsigned int alloc_flags);

42
mm/slub.c
View File

@ -2074,18 +2074,20 @@ static inline void mark_obj_codetag_empty(const void *obj)
slab_exts = slab_obj_exts(obj_slab);
if (slab_exts) {
struct slabobj_ext *ext;
union codetag_ref *ref;
get_slab_obj_exts(slab_exts);
ext = slab_obj_ext(obj_slab->slab_cache, obj_slab, slab_exts, obj);
ref = slab_obj_ext_codetag_ref(obj_slab, ext);
if (unlikely(is_codetag_empty(&ext->ref))) {
if (unlikely(is_codetag_empty(ref))) {
put_slab_obj_exts(slab_exts);
return;
}
/* codetag should be NULL here */
WARN_ON(ext->ref.ct);
set_codetag_empty(&ext->ref);
WARN_ON(ref->ct);
set_codetag_empty(ref);
put_slab_obj_exts(slab_exts);
}
}
@ -2095,19 +2097,22 @@ static inline bool mark_failed_objexts_alloc(struct slab *slab)
return cmpxchg(&slab->obj_exts, 0, OBJEXTS_ALLOC_FAIL) == 0;
}
static inline void handle_failed_objexts_alloc(unsigned long obj_exts,
struct slabobj_ext *vec, unsigned int objects)
static inline void handle_failed_objexts_alloc(struct slab *slab,
unsigned long obj_exts, struct slabobj_ext *vec)
{
/*
* If vector previously failed to allocate then we have live
* objects with no tag reference. Mark all references in this
* vector as empty to avoid warnings later on.
*/
if (obj_exts == OBJEXTS_ALLOC_FAIL) {
unsigned int i;
if (obj_exts != OBJEXTS_ALLOC_FAIL)
return;
for (i = 0; i < objects; i++)
set_codetag_empty(&vec[i].ref);
for (unsigned int i = 0; i < slab->objects; i++) {
union codetag_ref *ref = slab_obj_ext_codetag_ref(slab, vec);
set_codetag_empty(ref);
vec++;
}
}
@ -2115,8 +2120,8 @@ static inline void handle_failed_objexts_alloc(unsigned long 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) {}
static inline void handle_failed_objexts_alloc(struct slab *slab,
unsigned long obj_exts, struct slabobj_ext *vec) {}
#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */
@ -2184,7 +2189,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
#endif
retry:
old_exts = READ_ONCE(slab->obj_exts);
handle_failed_objexts_alloc(old_exts, vec, slab->objects);
handle_failed_objexts_alloc(slab, old_exts, vec);
if (new_slab) {
/*
@ -2364,9 +2369,15 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags,
* check should be added before alloc_tag_add().
*/
if (obj_exts) {
union codetag_ref *ref;
get_slab_obj_exts(obj_exts);
obj_ext = slab_obj_ext(s, slab, obj_exts, object);
alloc_tag_add(&obj_ext->ref, current->alloc_tag, s->size);
ref = slab_obj_ext_codetag_ref(slab, obj_ext);
alloc_tag_add(ref, current->alloc_tag, s->size);
put_slab_obj_exts(obj_exts);
} else {
alloc_tag_set_inaccurate(current->alloc_tag);
@ -2398,10 +2409,13 @@ __alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p
get_slab_obj_exts(obj_exts);
for (int i = 0; i < objects; i++) {
struct slabobj_ext *ext;
if (is_kfence_address(p[i]))
continue;
alloc_tag_sub(&slab_obj_ext(s, slab, obj_exts, p[i])->ref, s->size);
ext = slab_obj_ext(s, slab, obj_exts, p[i]);
alloc_tag_sub(slab_obj_ext_codetag_ref(slab, ext), s->size);
}
put_slab_obj_exts(obj_exts);
}