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author | Roman Gushchin <roman.gushchin@linux.dev> | 2023-10-20 01:53:44 +0300 |
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committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-26 02:47:11 +0300 |
commit | e86828e5446d95676835679837d995dec188d2be (patch) | |
tree | d74a46f7cf5209fe29e3337b3b280e3c728932b7 /include/linux/memcontrol.h | |
parent | 675d6c9b59e313ca2573c93e8fd87011a99bb8ce (diff) | |
download | linux-e86828e5446d95676835679837d995dec188d2be.tar.xz |
mm: kmem: scoped objcg protection
Switch to a scope-based protection of the objcg pointer on slab/kmem
allocation paths. Instead of using the get_() semantics in the
pre-allocation hook and put the reference afterwards, let's rely on the
fact that objcg is pinned by the scope.
It's possible because:
1) if the objcg is received from the current task struct, the task is
keeping a reference to the objcg.
2) if the objcg is received from an active memcg (remote charging),
the memcg is pinned by the scope and has a reference to the
corresponding objcg.
Link: https://lkml.kernel.org/r/20231019225346.1822282-5-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/memcontrol.h')
-rw-r--r-- | include/linux/memcontrol.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index cc110cc8fdfc..8006bc3bd7bf 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1796,6 +1796,15 @@ bool mem_cgroup_kmem_disabled(void); int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order); void __memcg_kmem_uncharge_page(struct page *page, int order); +/* + * The returned objcg pointer is safe to use without additional + * protection within a scope. The scope is defined either by + * the current task (similar to the "current" global variable) + * or by set_active_memcg() pair. + * Please, use obj_cgroup_get() to get a reference if the pointer + * needs to be used outside of the local scope. + */ +struct obj_cgroup *current_obj_cgroup(void); struct obj_cgroup *get_obj_cgroup_from_current(void); struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio); |