From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Subject: Re: [PATCH v4 3/4] mm/page_owner: Print memcg information Date: Thu, 3 Feb 2022 08:53:10 +0200 Message-ID: References: <20220131192308.608837-5-longman@redhat.com> <20220202203036.744010-4-longman@redhat.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643871201; bh=9nbtztfsgUhdr6aIZKYDMaKCReVO1EVdAswxzSjNC7E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=L6HEisU3wiHHxL8R9caiTeqrkK56FJXhwb2DFel+9K7/RdNm4Abym6AZjPQJ+NRIG RUmDLCvDW+mWgyKh8KuFV1evSRBK58szRcB/zqQzJv+AxciTxWg8rz133mfo6wSxUi 9c2ELDV7ixzAhlyQEz7+VvbHhyH1QoadIgBpJBu5nUpDAha3FFEuOXoqJlgQp2p6Hv gPkrqy9u/H3pGZmDePLjGeGyXE5NXCe7adhLerCiQsWgbnb4LELuRs/bSzlztvlAds Q7suEazu8PcoROGWUdjBttRsFysrf0TPvRT9JysqR1aAii9GBOGpVSCrzoq3fW9HVA YbQYF9iNsK73g== Content-Disposition: inline In-Reply-To: <20220202203036.744010-4-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Waiman Long Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Ira Weiny , David Rientjes , Roman Gushchin , Rafael Aquini On Wed, Feb 02, 2022 at 03:30:35PM -0500, Waiman Long wrote: > 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. > > Signed-off-by: Waiman Long > Acked-by: David Rientjes > Acked-by: Roman Gushchin Acked-by: Mike Rapoport And my akcs for the first two patches are missing somehow in v4... > --- > mm/page_owner.c | 42 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 42 insertions(+) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 28dac73e0542..f7820357e4d4 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 +326,45 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, > 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_t count, unsigned long pfn, > 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; > -- > 2.27.0 > > -- Sincerely yours, Mike.