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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 C3A44C282CD for ; Tue, 29 Jan 2019 00:15:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B4972175B for ; Tue, 29 Jan 2019 00:15:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727198AbfA2APM (ORCPT ); Mon, 28 Jan 2019 19:15:12 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:59394 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726713AbfA2APL (ORCPT ); Mon, 28 Jan 2019 19:15:11 -0500 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id CA9DD254A; Tue, 29 Jan 2019 00:15:10 +0000 (UTC) Date: Mon, 28 Jan 2019 16:15:09 -0800 From: Andrew Morton To: Sandeep Patil Cc: vbabka@suse.cz, adobriyan@gmail.com, avagin@openvz.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@android.com, dancol@google.com Subject: Re: [PATCH] mm: proc: smaps_rollup: Fix pss_locked calculation Message-Id: <20190128161509.5085cacf939463f1c22e0550@linux-foundation.org> In-Reply-To: <20190121011049.160505-1-sspatil@android.com> References: <20190121011049.160505-1-sspatil@android.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 20 Jan 2019 17:10:49 -0800 Sandeep Patil wrote: > The 'pss_locked' field of smaps_rollup was being calculated incorrectly > as it accumulated the current pss everytime a locked VMA was found. > > Fix that by making sure we record the current pss value before each VMA > is walked. So, we can only add the delta if the VMA was found to be > VM_LOCKED. > > ... > > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -709,6 +709,7 @@ static void smap_gather_stats(struct vm_area_struct *vma, > #endif > .mm = vma->vm_mm, > }; > + unsigned long pss; > > smaps_walk.private = mss; > > @@ -737,11 +738,12 @@ static void smap_gather_stats(struct vm_area_struct *vma, > } > } > #endif > - > + /* record current pss so we can calculate the delta after page walk */ > + pss = mss->pss; > /* mmap_sem is held in m_start */ > walk_page_vma(vma, &smaps_walk); > if (vma->vm_flags & VM_LOCKED) > - mss->pss_locked += mss->pss; > + mss->pss_locked += mss->pss - pss; > } This seems to be a rather obscure way of accumulating mem_size_stats.pss_locked. Wouldn't it make more sense to do this in smaps_account(), wherever we increment mem_size_stats.pss? It would be a tiny bit less efficient but I think that the code cleanup justifies such a cost?