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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 E714FC5DF63 for ; Wed, 6 Nov 2019 05:17:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 951F5206A3 for ; Wed, 6 Nov 2019 05:17:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="CrzJpAaI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 951F5206A3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5B7206B0276; Wed, 6 Nov 2019 00:17:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 540806B0277; Wed, 6 Nov 2019 00:17:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 454EB6B0278; Wed, 6 Nov 2019 00:17:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 305D16B0276 for ; Wed, 6 Nov 2019 00:17:06 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id D997B181AEF0B for ; Wed, 6 Nov 2019 05:17:05 +0000 (UTC) X-FDA: 76124693610.03.test78_3de8f68c19d5f X-HE-Tag: test78_3de8f68c19d5f X-Filterd-Recvd-Size: 4499 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Wed, 6 Nov 2019 05:17:05 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EE5F4217F4; Wed, 6 Nov 2019 05:17:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573017424; bh=KUmijE95Xvc0HyyoAL7SGK4urv4VVLqUFykkOHkDeN4=; h=Date:From:To:Subject:From; b=CrzJpAaINSLmpt7y2iMrrbVFTsdlRY8/4lhKyO8a7tBXi5fAEVM6qBFnM7O9recn8 43wLxeqldQMRsyn0MXb+E0jtkn0kWvkQNIc0k7YpOHjAGxPNj6ejLCGQ6Ga/cUaSSS Xq24zWCNA9ezeqFu2oYygITP/piZVU8wfms8hhBk= Date: Tue, 05 Nov 2019 21:17:03 -0800 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, daniel.m.jordan@oracle.com, guro@fb.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, n-horiguchi@ah.jp.nec.com, rientjes@google.com, shakeelb@google.com, stable@vger.kernel.org, torvalds@linux-foundation.org, vdavydov.dev@gmail.com Subject: [patch 14/17] mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly Message-ID: <20191106051703.QdQBp46KO%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Roman Gushchin Subject: mm: slab: make page_cgroup_ino() to recognize non-compound slab pages properly page_cgroup_ino() doesn't return a valid memcg pointer for non-compound slab pages, because it depends on PgHead AND PgSlab flags to be set to determine the memory cgroup from the kmem_cache. It's correct for compound pages, but not for generic small pages. Those don't have PgHead set, so it ends up returning zero. Fix this by replacing the condition to PageSlab() && !PageTail(). Before this patch: [root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/user@0.service/ | grep slab 0x0000000000000080 38 0 _______S___________________________________ slab After this patch: [root@localhost ~]# ./page-types -c /sys/fs/cgroup/user.slice/user-0.slice/user@0.service/ | grep slab 0x0000000000000080 147 0 _______S___________________________________ slab Also, hwpoison_filter_task() uses output of page_cgroup_ino() in order to filter error injection events based on memcg. So if page_cgroup_ino() fails to return memcg pointer, we just fail to inject memory error. Considering that hwpoison filter is for testing, affected users are limited and the impact should be marginal. [n-horiguchi@ah.jp.nec.com: changelog additions] Link: http://lkml.kernel.org/r/20191031012151.2722280-1-guro@fb.com Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages") Signed-off-by: Roman Gushchin Reviewed-by: Shakeel Butt Acked-by: David Rientjes Cc: Vladimir Davydov Cc: Daniel Jordan Cc: Naoya Horiguchi Cc: Signed-off-by: Andrew Morton --- mm/memcontrol.c | 2 +- mm/slab.h | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) --- a/mm/memcontrol.c~mm-slab-make-page_cgroup_ino-to-recognize-non-compound-slab-pages-properly +++ a/mm/memcontrol.c @@ -484,7 +484,7 @@ ino_t page_cgroup_ino(struct page *page) unsigned long ino = 0; rcu_read_lock(); - if (PageHead(page) && PageSlab(page)) + if (PageSlab(page) && !PageTail(page)) memcg = memcg_from_slab_page(page); else memcg = READ_ONCE(page->mem_cgroup); --- a/mm/slab.h~mm-slab-make-page_cgroup_ino-to-recognize-non-compound-slab-pages-properly +++ a/mm/slab.h @@ -323,8 +323,8 @@ static inline struct kmem_cache *memcg_r * 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, * which do not have slab_cache pointer set. - * So this function assumes that the page can pass PageHead() and PageSlab() - * checks. + * So this function assumes that the page can pass PageSlab() && !PageTail() + * check. * * The kmem_cache can be reparented asynchronously. The caller must ensure * the memcg lifetime, e.g. by taking rcu_read_lock() or cgroup_mutex. _