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 X-Spam-Level: X-Spam-Status: No, score=-14.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0428CC433E0 for ; Sat, 20 Jun 2020 00:32:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C924D22A85 for ; Sat, 20 Jun 2020 00:32:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="W++wx9a2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730926AbgFTAcA (ORCPT ); Fri, 19 Jun 2020 20:32:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730293AbgFTAb5 (ORCPT ); Fri, 19 Jun 2020 20:31:57 -0400 Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 739A1C06174E for ; Fri, 19 Jun 2020 17:31:57 -0700 (PDT) Received: by mail-lj1-x242.google.com with SMTP id i27so13389489ljb.12 for ; Fri, 19 Jun 2020 17:31:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GC0X1A1u34H3gu6Exp5dVJ6e1IpoU2YLjA8YbGTqXlw=; b=W++wx9a2bt4hjgiiNkEK90qCv41Wyd+Ab5FPHyTC/GMQMSKbMza18eMbtEhN2IyzgK qBNiyVBONw+GDIqeRL2QxuYpOrX1s9HMDL40l46jK1dhlg0qiIRKuQWJAkZKxU+SV5rg puck3Xt+CpyX6uh9LETS0yLdXhfErj8MWBlx6osdG1vwLuiG+/9eQvB7uMG7oh2/NiCH oYmBSxYBg2i0NGOK5UqwB8LsATuseC4JQ5PtQ0MIw29puHYicw/xwYUXFAjIAL82OTF/ /cPSPnfmAkBwyXlwHbWMiv2b1sfe1CtGDw7yvhaRDsXnIGZ1sETrvnS3rsqbENvoauFe lLxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=GC0X1A1u34H3gu6Exp5dVJ6e1IpoU2YLjA8YbGTqXlw=; b=oAwDzDmqKSed1ckACcToS87xeWa09T8aDRrWfcgIRxjXbXX7jqAUwSJqT0eZQV1F0+ 8JlOjhpdIwMdmBEqD9C/F/K+VfB+552OlgN+O2K6D2bo6hkN+2khlWuXeWdIr9E5bOLy U/hE8rsLaPdE3bAVN6PjqexZ61eDlpnfNVUIoE3wfBGsTtdoJaArLHNvvVPlItoy+SHW YOAquhERfzKxyQf6S/5UaD7Q/KLV4tfdAsy60z44sWKxee5PjGBAepXDRf+8cDWg11Bm XxKVlktOsaguu9PJ6Dz9BjkZHZHa9zPgG40mI6BPlMFoQ66yIilq0ctDst+eP2jMuWES 4kHg== X-Gm-Message-State: AOAM531qZeyEzY9L2usfUcdnxD3+pkiLDl1x9mrIGCtlqnvX7ffQFVlO D8Njl266sAfg5YNTXzHuCI4yeLPmr/nWDr4txObsyA== X-Google-Smtp-Source: ABdhPJwpvTKkWRXgxu6zXw3WSGE6mJFBDibW77din/FtDcY/O0Rnc79GZLGHzqU1j9mW/Df+g6149erumhq14TW0lEE= X-Received: by 2002:a2e:a58a:: with SMTP id m10mr3091893ljp.347.1592613115441; Fri, 19 Jun 2020 17:31:55 -0700 (PDT) MIME-Version: 1.0 References: <20200608230654.828134-1-guro@fb.com> <20200608230654.828134-8-guro@fb.com> <20200620002513.GD237539@carbon.dhcp.thefacebook.com> In-Reply-To: <20200620002513.GD237539@carbon.dhcp.thefacebook.com> From: Shakeel Butt Date: Fri, 19 Jun 2020 17:31:44 -0700 Message-ID: Subject: Re: [PATCH v6 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages To: Roman Gushchin Cc: Andrew Morton , Christoph Lameter , Johannes Weiner , Michal Hocko , Linux MM , Vlastimil Babka , Kernel Team , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 19, 2020 at 5:25 PM Roman Gushchin wrote: > > On Fri, Jun 19, 2020 at 09:36:16AM -0700, Shakeel Butt wrote: > > On Mon, Jun 8, 2020 at 4:07 PM Roman Gushchin wrote: > > > > > > Allocate and release memory to store obj_cgroup pointers for each > > > non-root slab page. Reuse page->mem_cgroup pointer to store a pointer > > > to the allocated space. > > > > > > To distinguish between obj_cgroups and memcg pointers in case > > > when it's not obvious which one is used (as in page_cgroup_ino()), > > > let's always set the lowest bit in the obj_cgroup case. > > > > > > > I think the commit message should talk about the potential overhead > > (i.e an extra pointer for each object) along with the justifications > > (i.e. less internal fragmentation and potentially more savings than > > the overhead). > > How about adding the following chunk? I don't like forward links in > commit messages, so maybe putting it into the cover letter? > > This commit temporarily increases the memory footprint of the kernel memory > accounting. To store obj_cgroup pointers we'll need a place for an > objcg_pointer for each allocated object. However, the following patches > in the series will enable sharing of slab pages between memory cgroups, > which will dramatically increase the total slab utilization. And the final > memory footprint will be significantly smaller than before. > This looks good to me. > > > > > Signed-off-by: Roman Gushchin > > > Reviewed-by: Vlastimil Babka > > > --- > > > include/linux/mm_types.h | 5 +++- > > > include/linux/slab_def.h | 6 +++++ > > > include/linux/slub_def.h | 5 ++++ > > > mm/memcontrol.c | 17 +++++++++++--- > > > mm/slab.h | 49 ++++++++++++++++++++++++++++++++++++++++ > > > 5 files changed, 78 insertions(+), 4 deletions(-) > > > > > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > > > index 64ede5f150dc..0277fbab7c93 100644 > > > --- a/include/linux/mm_types.h > > > +++ b/include/linux/mm_types.h > > > @@ -198,7 +198,10 @@ struct page { > > > atomic_t _refcount; > > > > > > #ifdef CONFIG_MEMCG > > > - struct mem_cgroup *mem_cgroup; > > > + union { > > > + struct mem_cgroup *mem_cgroup; > > > + struct obj_cgroup **obj_cgroups; > > > + }; > > > #endif > > > > > > /* > > > diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h > > > index abc7de77b988..ccda7b9669a5 100644 > > > --- a/include/linux/slab_def.h > > > +++ b/include/linux/slab_def.h > > > @@ -114,4 +114,10 @@ static inline unsigned int obj_to_index(const struct kmem_cache *cache, > > > return reciprocal_divide(offset, cache->reciprocal_buffer_size); > > > } > > > > > > +static inline int objs_per_slab_page(const struct kmem_cache *cache, > > > + const struct page *page) > > > +{ > > > + return cache->num; > > > +} > > > + > > > #endif /* _LINUX_SLAB_DEF_H */ > > > diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h > > > index 30e91c83d401..f87302dcfe8c 100644 > > > --- a/include/linux/slub_def.h > > > +++ b/include/linux/slub_def.h > > > @@ -198,4 +198,9 @@ static inline unsigned int obj_to_index(const struct kmem_cache *cache, > > > return __obj_to_index(cache, page_address(page), obj); > > > } > > > > > > +static inline int objs_per_slab_page(const struct kmem_cache *cache, > > > + const struct page *page) > > > +{ > > > + return page->objects; > > > +} > > > #endif /* _LINUX_SLUB_DEF_H */ > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 7ff66275966c..2020c7542aa1 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -569,10 +569,21 @@ ino_t page_cgroup_ino(struct page *page) > > > unsigned long ino = 0; > > > > > > rcu_read_lock(); > > > - if (PageSlab(page) && !PageTail(page)) > > > + if (PageSlab(page) && !PageTail(page)) { > > > memcg = memcg_from_slab_page(page); > > > - else > > > - memcg = READ_ONCE(page->mem_cgroup); > > > + } else { > > > + memcg = page->mem_cgroup; > > > + > > > + /* > > > + * The lowest bit set means that memcg isn't a valid > > > + * memcg pointer, but a obj_cgroups pointer. > > > + * In this case the page is shared and doesn't belong > > > + * to any specific memory cgroup. > > > + */ > > > + if ((unsigned long) memcg & 0x1UL) > > > + memcg = NULL; > > > + } > > > + > > > while (memcg && !(memcg->css.flags & CSS_ONLINE)) > > > memcg = parent_mem_cgroup(memcg); > > > if (memcg) > > > diff --git a/mm/slab.h b/mm/slab.h > > > index 8a574d9361c1..a1633ea15fbf 100644 > > > --- a/mm/slab.h > > > +++ b/mm/slab.h > > > @@ -319,6 +319,18 @@ static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s) > > > return s->memcg_params.root_cache; > > > } > > > > > > +static inline struct obj_cgroup **page_obj_cgroups(struct page *page) > > > +{ > > > + /* > > > + * page->mem_cgroup and page->obj_cgroups are sharing the same > > > + * space. To distinguish between them in case we don't know for sure > > > + * that the page is a slab page (e.g. page_cgroup_ino()), let's > > > + * always set the lowest bit of obj_cgroups. > > > + */ > > > + return (struct obj_cgroup **) > > > + ((unsigned long)page->obj_cgroups & ~0x1UL); > > > +} > > > + > > > /* > > > * Expects a pointer to a slab page. Please note, that PageSlab() check > > > * isn't sufficient, as it returns true also for tail compound slab pages, > > > @@ -406,6 +418,26 @@ static __always_inline void memcg_uncharge_slab(struct page *page, int order, > > > percpu_ref_put_many(&s->memcg_params.refcnt, nr_pages); > > > } > > > > > > +static inline int memcg_alloc_page_obj_cgroups(struct page *page, > > > + struct kmem_cache *s, gfp_t gfp) > > > +{ > > > + unsigned int objects = objs_per_slab_page(s, page); > > > + void *vec; > > > + > > > + vec = kcalloc(objects, sizeof(struct obj_cgroup *), gfp); > > > > Should the above allocation be on the same node as the page? > > Yeah, it's a clever idea. The following patch should do the trick. > Andrew, can you, please, squash this in? > > Thank you! > > Reviewed-by: Shakeel Butt > diff --git a/mm/slab.h b/mm/slab.h > index 0a31600a0f5c..2a036eefbd7e 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -233,7 +233,8 @@ static inline int memcg_alloc_page_obj_cgroups(struct page *page, > unsigned int objects = objs_per_slab_page(s, page); > void *vec; > > - vec = kcalloc(objects, sizeof(struct obj_cgroup *), gfp); > + vec = kcalloc_node(objects, sizeof(struct obj_cgroup *), gfp, > + page_to_nid(page)); > if (!vec) > return -ENOMEM; >