From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 703E8C433F5 for ; Mon, 31 Jan 2022 20:51:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E88808D0001; Mon, 31 Jan 2022 15:51:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E5F768D0024; Mon, 31 Jan 2022 15:51:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4E0C8D0001; Mon, 31 Jan 2022 15:51:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay032.a.hostedemail.com [64.99.140.32]) by kanga.kvack.org (Postfix) with ESMTP id C66208D0024 for ; Mon, 31 Jan 2022 15:51:42 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 90C1ED45 for ; Mon, 31 Jan 2022 20:51:42 +0000 (UTC) X-FDA: 79091778444.01.D238A25 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf06.hostedemail.com (Postfix) with ESMTP id A22D9180007 for ; Mon, 31 Jan 2022 20:51:41 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id E5715CE1397; Mon, 31 Jan 2022 20:51:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 98B64C340E8; Mon, 31 Jan 2022 20:51:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643662297; bh=tX6vpO5C4zkX8VHS8hum/62LQzSNztcbGvWYKWQl7YE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ATkv6m2+GD3ZcijSZcw0eXCmRFRyUcncCfGLiwwxFRMBGVP/hL2/OESM2+Bm3BHSI jlJH35lFKnZYbczbzb/FHB3rFk1nPEj2ShQz7aM96eLsi1UbGVbFwn1Ms4sP35M9kc M8An6au1QzZfQdF3xzKgDywd0cp1yPLla9MoGki7NOLZipmkcWXTpbRuHa61iuI3oQ K9uBC9RYQ/nKdzj9xBLog3e02+1k7q0Ifg3TzvbMAIdZwk2Gr05ydV6fkPzsie9pdF TycV2WnZsNinTpOhpHvELyAGCTfj5jR1CA6bwyZCxWBzwLdeK4/55DZ0N+WwR9Kff8 smsdfdS1XajQQ== Date: Mon, 31 Jan 2022 22:51:24 +0200 From: Mike Rapoport To: Waiman Long Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Ira Weiny , David Rientjes , Roman Gushchin , Rafael Aquini Subject: Re: [PATCH v3 3/4] mm/page_owner: Print memcg information Message-ID: References: <20220131192308.608837-1-longman@redhat.com> <20220131192308.608837-4-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220131192308.608837-4-longman@redhat.com> X-Rspam-User: nil X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A22D9180007 X-Stat-Signature: 67j1eezernji7z3be4z6enot9yo99dsj Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=ATkv6m2+; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of rppt@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=rppt@kernel.org X-HE-Tag: 1643662301-901299 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jan 31, 2022 at 02:23:07PM -0500, Waiman Long wrote: > 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"); Don't we need to check for overflow here? > + > + 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); Ditto > +} > +#else /* CONFIG_MEMCG */ > +static inline void print_page_owner_memcg(char *kbuf, size_t count, int *pret, > + struct page *page) { } I think #ifdef inside the print_page_owner_memcg() functions will be simpler and clearer. > +#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 can go over count here. Why not make print_page_owner_memcg() an int so that the call will be consistent with other calls in print_page_owner(): ret += print_page_owner_memcg(kbuf, count, page); if (ret >= count) goto err; > ret += snprintf(kbuf + ret, count - ret, "\n"); > if (ret >= count) > goto err; > -- > 2.27.0 > -- Sincerely yours, Mike.