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memcg: Convert mem_cgroup_from_obj_folio() to mem_cgroup_from_obj_slab()

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In preparation for splitting struct slab from struct page and struct
folio, convert the pointer to a slab rather than a folio.  This means
we can end up passing a NULL slab pointer to mem_cgroup_from_obj_slab()
if the pointer is not to a page allocated to slab, and we handle that
appropriately by returning NULL.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: cgroups@vger.kernel.org
Link: https://patch.msgid.link/20251113000932.1589073-15-willy@infradead.org
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Matthew Wilcox (Oracle)
2025-11-13 00:09:28 +00:00
committed by Vlastimil Babka
parent 5934b1be8d
commit b8557d109e
1 changed files with 16 additions and 24 deletions
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40
mm/memcontrol.c
View File

@@ -2557,38 +2557,25 @@ static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
}
static __always_inline
struct mem_cgroup *mem_cgroup_from_obj_folio(struct folio *folio, void *p)
struct mem_cgroup *mem_cgroup_from_obj_slab(struct slab *slab, void *p)
{
/*
* Slab objects are accounted individually, not per-page.
* Memcg membership data for each individual object is saved in
* slab->obj_exts.
*/
if (folio_test_slab(folio)) {
struct slabobj_ext *obj_exts;
struct slab *slab;
unsigned int off;
slab = folio_slab(folio);
obj_exts = slab_obj_exts(slab);
if (!obj_exts)
return NULL;
off = obj_to_index(slab->slab_cache, slab, p);
if (obj_exts[off].objcg)
return obj_cgroup_memcg(obj_exts[off].objcg);
struct slabobj_ext *obj_exts;
unsigned int off;
obj_exts = slab_obj_exts(slab);
if (!obj_exts)
return NULL;
}
/*
* folio_memcg_check() is used here, because in theory we can encounter
* a folio where the slab flag has been cleared already, but
* slab->obj_exts has not been freed yet
* folio_memcg_check() will guarantee that a proper memory
* cgroup pointer or NULL will be returned.
*/
return folio_memcg_check(folio);
off = obj_to_index(slab->slab_cache, slab, p);
if (obj_exts[off].objcg)
return obj_cgroup_memcg(obj_exts[off].objcg);
return NULL;
}
/*
@@ -2602,10 +2589,15 @@ struct mem_cgroup *mem_cgroup_from_obj_folio(struct folio *folio, void *p)
*/
struct mem_cgroup *mem_cgroup_from_slab_obj(void *p)
{
struct slab *slab;
if (mem_cgroup_disabled())
return NULL;
return mem_cgroup_from_obj_folio(virt_to_folio(p), p);
slab = virt_to_slab(p);
if (slab)
return mem_cgroup_from_obj_slab(slab, p);
return folio_memcg_check(virt_to_folio(p));
}
static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg)