From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: [PATCH v3 3/4] mm/page_owner: Print memcg information Date: Mon, 31 Jan 2022 14:23:07 -0500 Message-ID: <20220131192308.608837-4-longman@redhat.com> References: <20220131192308.608837-1-longman@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643657013; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AqKO5lknN2+Nsr0yWLMZlCagaD5YFaBIvpU1YV0vjJ8=; b=D5HLeURrdhU7FmHdatBQz2nXIU/paVkcnKNrmYr7x6cyBCsqvRlnlzKJSZKENfKsV/8Hce 4Sf/23xr9hAOFaK7MpItlMXai9OCwvRw5lQf3YW78dh3hsfqZgJJNDUwDsWqCHqinJ3B4U xzoQ+uyYhiysfdaNt4lkdenE7pR4bjE= In-Reply-To: <20220131192308.608837-1-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Ira Weiny , Mike Rapoport , David Rientjes , Roman Gushchin , Rafael Aquini , Waiman Long It was found that a number of offlined 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 offlined 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 offlined memcgs, the page_owner feature is extended to print memory cgroup information especially whether the cgroup is offlined or not. Signed-off-by: Waiman Long Acked-by: David Rientjes --- mm/page_owner.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/mm/page_owner.c b/mm/page_owner.c index 28dac73e0542..a471c74c7fe0 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include "internal.h" @@ -325,6 +326,42 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, seq_putc(m, '\n'); } +#ifdef CONFIG_MEMCG +/* + * Looking for memcg information and print it out + */ +static inline void print_page_owner_memcg(char *kbuf, size_t count, int *pret, + struct page *page) +{ + unsigned long memcg_data = READ_ONCE(page->memcg_data); + struct mem_cgroup *memcg; + bool onlined; + char name[80]; + + if (!memcg_data) + return; + + if (memcg_data & MEMCG_DATA_OBJCGS) + *pret += scnprintf(kbuf + *pret, count - *pret, + "Slab cache page\n"); + + memcg = page_memcg_check(page); + if (!memcg) + return; + + onlined = (memcg->css.flags & CSS_ONLINE); + cgroup_name(memcg->css.cgroup, name, sizeof(name)); + *pret += scnprintf(kbuf + *pret, count - *pret, + "Charged %sto %smemcg %s\n", + PageMemcgKmem(page) ? "(via objcg) " : "", + onlined ? "" : "offlined ", + name); +} +#else /* CONFIG_MEMCG */ +static inline void print_page_owner_memcg(char *kbuf, size_t count, int *pret, + struct page *page) { } +#endif /* CONFIG_MEMCG */ + 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 +402,8 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, migrate_reason_names[page_owner->last_migrate_reason]); } + print_page_owner_memcg(kbuf, count, &ret, page); + ret += snprintf(kbuf + ret, count - ret, "\n"); if (ret >= count) goto err; -- 2.27.0