Commit becaba65 authored by Roman Gushchin's avatar Roman Gushchin Committed by Linus Torvalds
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mm: memcg/slab: fix obj_cgroup_charge() return value handling 



Commit 10befea9 ("mm: memcg/slab: use a single set of kmem_caches
for all allocations") introduced a regression into the handling of the
obj_cgroup_charge() return value.  If a non-zero value is returned
(indicating of exceeding one of memory.max limits), the allocation
should fail, instead of falling back to non-accounted mode.

To make the code more readable, move memcg_slab_pre_alloc_hook() and
memcg_slab_post_alloc_hook() calling conditions into bodies of these
hooks.

Fixes: 10befea9 ("mm: memcg/slab: use a single set of kmem_caches for all allocations")
Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201127161828.GD840171@carbon.dhcp.thefacebook.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2bf509d9

mm/slab.h

+24 −16
Original line number Diff line number Diff line
@@ -274,22 +274,32 @@ static inline size_t obj_full_size(struct kmem_cache *s) 
	return s->size + sizeof(struct obj_cgroup *);

}



static inline struct obj_cgroup *memcg_slab_pre_alloc_hook(struct kmem_cache *s,

							   size_t objects,

							   gfp_t flags)

/*

 * Returns false if the allocation should fail.

 */

static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s,

					     struct obj_cgroup **objcgp,

					     size_t objects, gfp_t flags)

{

	struct obj_cgroup *objcg;



	if (!memcg_kmem_enabled())

		return true;



	if (!(flags & __GFP_ACCOUNT) && !(s->flags & SLAB_ACCOUNT))

		return true;



	objcg = get_obj_cgroup_from_current();

	if (!objcg)

		return NULL;

		return true;



	if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s))) {

		obj_cgroup_put(objcg);

		return NULL;

		return false;

	}



	return objcg;

	*objcgp = objcg;

	return true;

}



static inline void mod_objcg_state(struct obj_cgroup *objcg,
@@ -315,7 +325,7 @@ static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, 
	unsigned long off;

	size_t i;



	if (!objcg)

	if (!memcg_kmem_enabled() || !objcg)

		return;



	flags &= ~__GFP_ACCOUNT;
@@ -400,11 +410,11 @@ static inline void memcg_free_page_obj_cgroups(struct page *page) 
{

}



static inline struct obj_cgroup *memcg_slab_pre_alloc_hook(struct kmem_cache *s,

							   size_t objects,

							   gfp_t flags)

static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s,

					     struct obj_cgroup **objcgp,

					     size_t objects, gfp_t flags)

{

	return NULL;

	return true;

}



static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s,
@@ -508,9 +518,8 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, 
	if (should_failslab(s, flags))

		return NULL;



	if (memcg_kmem_enabled() &&

	    ((flags & __GFP_ACCOUNT) || (s->flags & SLAB_ACCOUNT)))

		*objcgp = memcg_slab_pre_alloc_hook(s, size, flags);

	if (!memcg_slab_pre_alloc_hook(s, objcgp, size, flags))

		return NULL;



	return s;

}
@@ -529,7 +538,6 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, 
					 s->flags, flags);

	}



	if (memcg_kmem_enabled())

	memcg_slab_post_alloc_hook(s, objcg, flags, size, p);

}

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