Commit b8557d10 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Vlastimil Babka
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memcg: Convert mem_cgroup_from_obj_folio() to mem_cgroup_from_obj_slab() 



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: default avatarMatthew 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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent 5934b1be

mm/memcontrol.c

+16 −24
Original line number Diff line number Diff line
@@ -2557,19 +2557,16 @@ 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;
@@ -2581,16 +2578,6 @@ struct mem_cgroup *mem_cgroup_from_obj_folio(struct folio *folio, void *p) 
	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);

}



/*

 * Returns a pointer to the memory cgroup to which the kernel object is charged.

 * It is not suitable for objects allocated using vmalloc().
@@ -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)