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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE170E728D7 for ; Fri, 29 Sep 2023 18:42:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233215AbjI2Sm4 (ORCPT ); Fri, 29 Sep 2023 14:42:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233557AbjI2Smz (ORCPT ); Fri, 29 Sep 2023 14:42:55 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A762B1B8 for ; Fri, 29 Sep 2023 11:42:52 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 395C9C433C7; Fri, 29 Sep 2023 18:42:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1696012972; bh=rP5TLGsqzMQu/Mds5KPoa6JMZeY3rUvwQHsOSWmiBlU=; h=Date:To:From:Subject:From; b=WhOHwOhAAkgDyHGTql3B5+So1naXhrp6gnNSB2RS+sKgLWE1xHpN7ACIuE/ct/fgz v0+5kdDWAKqNBAuhMvO2v1Jr37IIXL0xxO5I8U+WmQKcUKktUiWAqpm2+FGucy/ypC XJsZfKoFwZw1qfoxTHBTWLrvmuJyXEx+hYJHxHsA= Date: Fri, 29 Sep 2023 11:42:51 -0700 To: mm-commits@vger.kernel.org, vbabka@suse.cz, shakeelb@google.com, rientjes@google.com, muchun.song@linux.dev, mhocko@kernel.org, hannes@cmpxchg.org, dennis@kernel.org, roman.gushchin@linux.dev, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-kmem-make-memcg-keep-a-reference-to-the-original-objcg.patch added to mm-unstable branch Message-Id: <20230929184252.395C9C433C7@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: kmem: make memcg keep a reference to the original objcg has been added to the -mm mm-unstable branch. Its filename is mm-kmem-make-memcg-keep-a-reference-to-the-original-objcg.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kmem-make-memcg-keep-a-reference-to-the-original-objcg.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Roman Gushchin Subject: mm: kmem: make memcg keep a reference to the original objcg Date: Fri, 29 Sep 2023 11:00:53 -0700 Keep a reference to the original objcg object for the entire life of a memcg structure. This allows to simplify the synchronization on the kernel memory allocation paths: pinning a (live) memcg will also pin the corresponding objcg. The memory overhead of this change is minimal because object cgroups usually outlive their corresponding memory cgroups even without this change, so it's only an additional pointer per memcg. Link: https://lkml.kernel.org/r/20230929180056.1122002-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin (Cruise) Cc: David Rientjes Cc: Dennis Zhou Cc: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Shakeel Butt Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/memcontrol.h | 8 +++++++- mm/memcontrol.c | 5 +++++ 2 files changed, 12 insertions(+), 1 deletion(-) --- a/include/linux/memcontrol.h~mm-kmem-make-memcg-keep-a-reference-to-the-original-objcg +++ a/include/linux/memcontrol.h @@ -290,7 +290,13 @@ struct mem_cgroup { #ifdef CONFIG_MEMCG_KMEM int kmemcg_id; - struct obj_cgroup __rcu *objcg; + /* + * memcg->objcg is wiped out as a part of the objcg repaprenting + * process. memcg->orig_objcg preserves a pointer (and a reference) + * to the original objcg until the end of live of memcg. + */ + struct obj_cgroup __rcu *objcg; + struct obj_cgroup *orig_objcg; /* list of inherited objcgs, protected by objcg_lock */ struct list_head objcg_list; #endif --- a/mm/memcontrol.c~mm-kmem-make-memcg-keep-a-reference-to-the-original-objcg +++ a/mm/memcontrol.c @@ -3843,6 +3843,8 @@ static int memcg_online_kmem(struct mem_ objcg->memcg = memcg; rcu_assign_pointer(memcg->objcg, objcg); + obj_cgroup_get(objcg); + memcg->orig_objcg = objcg; static_branch_enable(&memcg_kmem_online_key); @@ -5350,6 +5352,9 @@ static void __mem_cgroup_free(struct mem { int node; + if (memcg->orig_objcg) + obj_cgroup_put(memcg->orig_objcg); + for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); kfree(memcg->vmstats); _ Patches currently in -mm which might be from roman.gushchin@linux.dev are mm-kmem-optimize-get_obj_cgroup_from_current.patch mm-kmem-add-direct-objcg-pointer-to-task_struct.patch mm-kmem-make-memcg-keep-a-reference-to-the-original-objcg.patch mm-kmem-scoped-objcg-protection.patch percpu-scoped-objcg-protection.patch