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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 AA509C43331 for ; Wed, 1 Apr 2020 23:04:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66F702077D for ; Wed, 1 Apr 2020 23:04:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585782275; bh=hvlfZA46q1Cbn9vzPaFNviFruJ3+E69/UrF7Q260jWI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=MD9nhY/iQNhsBe7ha/fBpBgPQv+K+lP9Jos2CeoK9cg/Tj33gyhscYE9+NQDsI5to +XLALk6jREb5UJwjAKuXjOcb5aEesLuRDypP6PAqj2BZ4LdSSSTuVu5whrlonREwVV +DVjs7SxG1th1eUt/tsKVoBVFhXMwa6WW7JhOmI0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733289AbgDAXEe (ORCPT ); Wed, 1 Apr 2020 19:04:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:57586 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732667AbgDAXEe (ORCPT ); Wed, 1 Apr 2020 19:04:34 -0400 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 10BE2206F5; Wed, 1 Apr 2020 23:04:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585782273; bh=hvlfZA46q1Cbn9vzPaFNviFruJ3+E69/UrF7Q260jWI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=GGZCjuqeRlaC7s0tXF7sXwGeWSLjI/NDe6RW8rYNge/jk10tPeAqHj1NZ9vG34MPr 34VXcc/AMPz6Gn236HbKtva4wADAsKF+La3YOH1eebKeN+RNMAMAG9nNPYjzJj8bhn wfdEbMg5om3D2gxX6iW2UY+uT2nOGqjJyQ04ry74= Date: Wed, 1 Apr 2020 16:04:32 -0700 From: Andrew Morton To: "Huang, Ying" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrea Arcangeli , "Kirill A . Shutemov" , Zi Yan , Vlastimil Babka , Alexey Dobriyan , Michal Hocko , Konstantin Khlebnikov , =?ISO-8859-1?Q?J=E9r=F4me?= Glisse , Yang Shi Subject: Re: [PATCH] /proc/PID/smaps: Add PMD migration entry parsing Message-Id: <20200401160432.855bba5b210c7b4bbf6c56ef@linux-foundation.org> In-Reply-To: <20200331085604.1260162-1-ying.huang@intel.com> References: <20200331085604.1260162-1-ying.huang@intel.com> X-Mailer: Sylpheed 3.5.1 (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 Tue, 31 Mar 2020 16:56:04 +0800 "Huang, Ying" wrote: > From: Huang Ying > > Now, when read /proc/PID/smaps, the PMD migration entry in page table is simply > ignored. To improve the accuracy of /proc/PID/smaps, its parsing and processing > is added. It would be helpful to show the before-and-after output in the changelog. > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -548,8 +548,17 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, > bool locked = !!(vma->vm_flags & VM_LOCKED); > struct page *page; > > - /* FOLL_DUMP will return -EFAULT on huge zero page */ > - page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP); > + if (pmd_present(*pmd)) { > + /* FOLL_DUMP will return -EFAULT on huge zero page */ > + page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP); > + } else if (unlikely(is_swap_pmd(*pmd))) { > + swp_entry_t entry = pmd_to_swp_entry(*pmd); > + > + VM_BUG_ON(!is_migration_entry(entry)); I don't think this justifies nuking the kernel. A WARN()-and-recover would be better. > + page = migration_entry_to_page(entry); > + } else { > + return; > + } > if (IS_ERR_OR_NULL(page)) > return; > if (PageAnon(page)) > @@ -578,8 +587,7 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, > > ptl = pmd_trans_huge_lock(pmd, vma); > if (ptl) { > - if (pmd_present(*pmd)) > - smaps_pmd_entry(pmd, addr, walk); > + smaps_pmd_entry(pmd, addr, walk); > spin_unlock(ptl); > goto out; > }