From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 078/155] mm, memcg: prevent memory.swap.max load tearing Date: Wed, 01 Apr 2020 21:07:30 -0700 Message-ID: <20200402040730.jK4QNPwaV%akpm@linux-foundation.org> References: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:58670 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726963AbgDBEHd (ORCPT ); Thu, 2 Apr 2020 00:07:33 -0400 In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, chris@chrisdown.name, guro@fb.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, tj@kernel.org, torvalds@linux-foundation.org From: Chris Down Subject: mm, memcg: prevent memory.swap.max load tearing The write side of this is xchg()/smp_mb(), so that's all good. Just a few sites missing a READ_ONCE. Link: http://lkml.kernel.org/r/bbec2c3d822217334855c8877a9d28b2a6d395fb.1584034301.git.chris@chrisdown.name Signed-off-by: Chris Down Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Roman Gushchin Cc: Tejun Heo Signed-off-by: Andrew Morton --- mm/memcontrol.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/memcontrol.c~mm-memcg-prevent-memoryswapmax-load-tearing +++ a/mm/memcontrol.c @@ -1525,7 +1525,7 @@ void mem_cgroup_print_oom_meminfo(struct if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->swap)), - K((u64)memcg->swap.max), memcg->swap.failcnt); + K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt); else { pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->memsw)), @@ -1558,7 +1558,7 @@ unsigned long mem_cgroup_get_max(struct unsigned long swap_max; memsw_max = memcg->memsw.max; - swap_max = memcg->swap.max; + swap_max = READ_ONCE(memcg->swap.max); swap_max = min(swap_max, (unsigned long)total_swap_pages); max = min(max + swap_max, memsw_max); } @@ -7117,7 +7117,8 @@ bool mem_cgroup_swap_full(struct page *p return false; for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) - if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max) + if (page_counter_read(&memcg->swap) * 2 >= + READ_ONCE(memcg->swap.max)) return true; return false; _