From: Roman Gushchin <guro@xxxxxx>
Subject: mm: memcg/slab: fix obj_cgroup_charge() return value handling
Commit 10befea91b61 ("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.
Link: https://lkml.kernel.org/r/20201127161828.GD840171@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 10befea91b61 ("mm: memcg/slab: use a single set of kmem_caches for all allocations")
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab.h | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
--- a/mm/slab.h~mm-memcg-slab-fix-obj_cgroup_charge-return-value-handling
+++ a/mm/slab.h
@@ -274,22 +274,32 @@ static inline size_t obj_full_size(struc
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
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_c
{
}
-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_pr
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;
}
@@ -529,8 +538,7 @@ static inline void slab_post_alloc_hook(
s->flags, flags);
}
- if (memcg_kmem_enabled())
- memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
+ memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
}
#ifndef CONFIG_SLOB
_
