From patchwork Sat Jun 27 03:33:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 222996 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=-4.0 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 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 9ABB8C433E0 for ; Sat, 27 Jun 2020 03:33:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 753692100A for ; Sat, 27 Jun 2020 03:33:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593228804; bh=TvQ3MZYCb+nzDtLp8y5E7FBB+5b5q2N6VeEB3pe1SLE=; h=Date:From:To:Subject:In-Reply-To:List-ID:From; b=X4AN+QebIjCRz1RnATNXC51h1T4UyMm9E2L74qhvrqJxnhA7cA9vHV8/LY3263r0v 9XP9SXIRqNiK6Eh1ShpRkJ75ovm7vM/su7QcDOo03jL/tNKpZN05QzOViJiNePCxD9 TBcn0TVa+c2hNWiT3mhXFz2867Lok5nT0Pm5NSOw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725957AbgF0DdY (ORCPT ); Fri, 26 Jun 2020 23:33:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:45038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725913AbgF0DdX (ORCPT ); Fri, 26 Jun 2020 23:33:23 -0400 Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (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 B134620CC7; Sat, 27 Jun 2020 03:33:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593228803; bh=TvQ3MZYCb+nzDtLp8y5E7FBB+5b5q2N6VeEB3pe1SLE=; h=Date:From:To:Subject:In-Reply-To:From; b=hXuCOikHNmGLQsAwOlZKtuA1IUIqC2hwYUwE2hUaq1WT3GbTbRH9cNeqiaNR58Szr Ytoz3g2jhPoiSZGL/vFLx4DtGtUtQiv6tAYOozeCzn/xPMwgX7J71Uvl+s/0mMnOt/ m1G6C+eSy/0YewhmSobLCPi8NCX11s41TKBui3fo= Date: Fri, 26 Jun 2020 20:33:22 -0700 From: Andrew Morton To: cl@linux.com, guro@fb.com, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, longman@redhat.com, mhocko@kernel.org, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, shakeelb@google.com, stable@vger.kernel.org, vdavydov.dev@gmail.com Subject: [merged] mm-slab-fix-sign-conversion-problem-in-memcg_uncharge_slab.patch removed from -mm tree Message-ID: <20200627033322.fMNqLPJU8%akpm@linux-foundation.org> In-Reply-To: <20200625202807.b630829d6fa55388148bee7d@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm, slab: fix sign conversion problem in memcg_uncharge_slab() has been removed from the -mm tree. Its filename was mm-slab-fix-sign-conversion-problem-in-memcg_uncharge_slab.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Waiman Long Subject: mm, slab: fix sign conversion problem in memcg_uncharge_slab() It was found that running the LTP test on a PowerPC system could produce erroneous values in /proc/meminfo, like: MemTotal: 531915072 kB MemFree: 507962176 kB MemAvailable: 1100020596352 kB Using bisection, the problem is tracked down to commit 9c315e4d7d8c ("mm: memcg/slab: cache page number in memcg_(un)charge_slab()"). In memcg_uncharge_slab() with a "int order" argument: unsigned int nr_pages = 1 << order; : mod_lruvec_state(lruvec, cache_vmstat_idx(s), -nr_pages); The mod_lruvec_state() function will eventually call the __mod_zone_page_state() which accepts a long argument. Depending on the compiler and how inlining is done, "-nr_pages" may be treated as a negative number or a very large positive number. Apparently, it was treated as a large positive number in that PowerPC system leading to incorrect stat counts. This problem hasn't been seen in x86-64 yet, perhaps the gcc compiler there has some slight difference in behavior. It is fixed by making nr_pages a signed value. For consistency, a similar change is applied to memcg_charge_slab() as well. Link: http://lkml.kernel.org/r/20200620184719.10994-1-longman@redhat.com Fixes: 9c315e4d7d8c ("mm: memcg/slab: cache page number in memcg_(un)charge_slab()"). Signed-off-by: Waiman Long Acked-by: Roman Gushchin Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Shakeel Butt Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Signed-off-by: Andrew Morton --- mm/slab.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/slab.h~mm-slab-fix-sign-conversion-problem-in-memcg_uncharge_slab +++ a/mm/slab.h @@ -348,7 +348,7 @@ static __always_inline int memcg_charge_ gfp_t gfp, int order, struct kmem_cache *s) { - unsigned int nr_pages = 1 << order; + int nr_pages = 1 << order; struct mem_cgroup *memcg; struct lruvec *lruvec; int ret; @@ -388,7 +388,7 @@ out: static __always_inline void memcg_uncharge_slab(struct page *page, int order, struct kmem_cache *s) { - unsigned int nr_pages = 1 << order; + int nr_pages = 1 << order; struct mem_cgroup *memcg; struct lruvec *lruvec;