From: Roman Gushchin Date: Sat, 2 Jul 2022 03:35:21 +0000 (-0700) Subject: mm: memcontrol: do not miss MEMCG_MAX events for enforced allocations X-Git-Tag: microblaze-v6.1~101^2~37 X-Git-Url: http://git.monstr.eu/?p=linux-2.6-microblaze.git;a=commitdiff_plain;h=d6e103a757fa7876e7ded76128d5dffe12402ab9 mm: memcontrol: do not miss MEMCG_MAX events for enforced allocations Yafang Shao reported an issue related to the accounting of bpf memory: if a bpf map is charged indirectly for memory consumed from an interrupt context and allocations are enforced, MEMCG_MAX events are not raised. It's not/less of an issue in a generic case because consequent allocations from a process context will trigger the direct reclaim and MEMCG_MAX events will be raised. However a bpf map can belong to a dying/abandoned memory cgroup, so there will be no allocations from a process context and no MEMCG_MAX events will be triggered. Link: https://lkml.kernel.org/r/20220702033521.64630-1-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin Reported-by: Yafang Shao Acked-by: Shakeel Butt Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Muchun Song Signed-off-by: Andrew Morton --- diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c5bfb3eacd08..767f49a6b987 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2577,6 +2577,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, bool passed_oom = false; bool may_swap = true; bool drained = false; + bool raised_max_event = false; unsigned long pflags; retry: @@ -2616,6 +2617,7 @@ retry: goto nomem; memcg_memory_event(mem_over_limit, MEMCG_MAX); + raised_max_event = true; psi_memstall_enter(&pflags); nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, @@ -2682,6 +2684,13 @@ nomem: if (!(gfp_mask & (__GFP_NOFAIL | __GFP_HIGH))) return -ENOMEM; force: + /* + * If the allocation has to be enforced, don't forget to raise + * a MEMCG_MAX event. + */ + if (!raised_max_event) + memcg_memory_event(mem_over_limit, MEMCG_MAX); + /* * The allocation either can't fail or will lead to more memory * being freed very soon. Allow memory usage go over the limit