From 2ef8ed7ddd2e6e69da7802be51af8ad71326a74f Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Tue, 14 Feb 2023 15:35:49 +0000 Subject: [PATCH] mm: percpu: fix incorrect size in pcpu_obj_full_size() The extra space which is used to store the obj_cgroup membership is only valid when kmemcg is enabled. The kmemcg can be disabled via the kernel parameter "cgroup.memory=nokmem" at boot time. This helper is also used in non-memcg code, for example the tracepoint, so we should fix it. It was found by code review when I was implementing bpf memory usage[1]. No real issue happens in production environment. [1]. https://lwn.net/Articles/921991/ Link: https://lkml.kernel.org/r/20230214153549.12291-1-laoar.shao@gmail.com Signed-off-by: Yafang Shao Reviewed-by: Roman Gushchin Acked-by: Dennis Zhou Cc: Tejun Heo Cc: Christoph Lameter Cc: Vasily Averin Signed-off-by: Andrew Morton --- mm/percpu-internal.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h index 70b1ea23f4d2..f9847c131998 100644 --- a/mm/percpu-internal.h +++ b/mm/percpu-internal.h @@ -4,6 +4,7 @@ #include #include +#include /* * pcpu_block_md is the metadata block struct. @@ -118,14 +119,15 @@ static inline int pcpu_chunk_map_bits(struct pcpu_chunk *chunk) * @size: size of area to allocate in bytes * * For each accounted object there is an extra space which is used to store - * obj_cgroup membership. Charge it too. + * obj_cgroup membership if kmemcg is not disabled. Charge it too. */ static inline size_t pcpu_obj_full_size(size_t size) { size_t extra_size = 0; #ifdef CONFIG_MEMCG_KMEM - extra_size += size / PCPU_MIN_ALLOC_SIZE * sizeof(struct obj_cgroup *); + if (!mem_cgroup_kmem_disabled()) + extra_size += size / PCPU_MIN_ALLOC_SIZE * sizeof(struct obj_cgroup *); #endif return size * num_possible_cpus() + extra_size;