From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0905D1FB7 for ; Fri, 25 Mar 2022 01:09:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C69BDC340EE; Fri, 25 Mar 2022 01:09:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648170548; bh=kClGRpQzIW+kEtb6ko5q3Tw/xoRFTPCFuWhBghh0l+I=; h=Date:To:From:In-Reply-To:Subject:From; b=AX1yc5Q58rEGRSlK8bZyZLs31VUFZxgHKPm5uhqbDo9lT3hJ+C1tvgeUYF98S0fMw bhRYlxgQh7C/Te+wKNG3YThmR2j77owhCmzjMeC+C3iPky9CGKemgnzWanFnbXUk+X RY9w8GY1ODkgsCWUcvcWEpgYcW4UsCFX87HjQOXQ= Date: Thu, 24 Mar 2022 18:09:08 -0700 To: vdavydov.dev@gmail.com,senozhatsky@chromium.org,rppt@linux.ibm.com,rostedt@goodmis.org,roman.gushchin@linux.dev,rientjes@google.com,pmladek@suse.com,mhocko@kernel.org,linux@rasmusvillemoes.dk,ira.weiny@intel.com,hannes@cmpxchg.org,guro@fb.com,aquini@redhat.com,andriy.shevchenko@linux.intel.com,longman@redhat.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220324180758.96b1ac7e17675d6bc474485e@linux-foundation.org> Subject: [patch 011/114] mm/page_owner: print memcg information Message-Id: <20220325010908.C69BDC340EE@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Waiman Long Subject: mm/page_owner: print memcg information It was found that a number of offline memcgs were not freed because they were pinned by some charged pages that were present. Even "echo 1 > /proc/sys/vm/drop_caches" wasn't able to free those pages. These offline but not freed memcgs tend to increase in number over time with the side effect that percpu memory consumption as shown in /proc/meminfo also increases over time. In order to find out more information about those pages that pin offline memcgs, the page_owner feature is extended to print memory cgroup information especially whether the cgroup is offline or not. RCU read lock is taken when memcg is being accessed to make sure that it won't be freed. Link: https://lkml.kernel.org/r/20220202203036.744010-4-longman@redhat.com Signed-off-by: Waiman Long Acked-by: David Rientjes Acked-by: Roman Gushchin Acked-by: Rafael Aquini Acked-by: Mike Rapoport Cc: Roman Gushchin Cc: Andy Shevchenko Cc: Ira Weiny Cc: Johannes Weiner Cc: Michal Hocko Cc: Petr Mladek Cc: Rasmus Villemoes Cc: Sergey Senozhatsky Cc: Steven Rostedt (Google) Cc: Vladimir Davydov Signed-off-by: Andrew Morton --- mm/page_owner.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) --- a/mm/page_owner.c~mm-page_owner-print-memcg-information +++ a/mm/page_owner.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include "internal.h" @@ -325,6 +326,45 @@ void pagetypeinfo_showmixedcount_print(s seq_putc(m, '\n'); } +/* + * Looking for memcg information and print it out + */ +static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret, + struct page *page) +{ +#ifdef CONFIG_MEMCG + unsigned long memcg_data; + struct mem_cgroup *memcg; + bool online; + char name[80]; + + rcu_read_lock(); + memcg_data = READ_ONCE(page->memcg_data); + if (!memcg_data) + goto out_unlock; + + if (memcg_data & MEMCG_DATA_OBJCGS) + ret += scnprintf(kbuf + ret, count - ret, + "Slab cache page\n"); + + memcg = page_memcg_check(page); + if (!memcg) + goto out_unlock; + + online = (memcg->css.flags & CSS_ONLINE); + cgroup_name(memcg->css.cgroup, name, sizeof(name)); + ret += scnprintf(kbuf + ret, count - ret, + "Charged %sto %smemcg %s\n", + PageMemcgKmem(page) ? "(via objcg) " : "", + online ? "" : "offline ", + name); +out_unlock: + rcu_read_unlock(); +#endif /* CONFIG_MEMCG */ + + return ret; +} + static ssize_t print_page_owner(char __user *buf, size_t count, unsigned long pfn, struct page *page, struct page_owner *page_owner, @@ -365,6 +405,8 @@ print_page_owner(char __user *buf, size_ migrate_reason_names[page_owner->last_migrate_reason]); } + ret = print_page_owner_memcg(kbuf, count, ret, page); + ret += snprintf(kbuf + ret, count - ret, "\n"); if (ret >= count) goto err; _