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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 EA3F5C43331 for ; Thu, 2 Apr 2020 01:42:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B32B920721 for ; Thu, 2 Apr 2020 01:42:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732783AbgDBBma (ORCPT ); Wed, 1 Apr 2020 21:42:30 -0400 Received: from mga09.intel.com ([134.134.136.24]:56444 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726319AbgDBBma (ORCPT ); Wed, 1 Apr 2020 21:42:30 -0400 IronPort-SDR: Ux0MT8tDp2uxmJRg8HIao4L222IaPNPyHZ4T5ZY8Vt7Q7F4t58ej46GcqulXR7h26LHlS58c2x 08AWvbt7Ua8Q== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2020 18:42:29 -0700 IronPort-SDR: Ow836iTrqGNe8ovWPKJP9uTb7WN4JK52gO/5s6TP5LGjeNhen6vF9xRq+FLhg3iniFRcZd+hHz OI0wFbSzty1A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,333,1580803200"; d="scan'208";a="252839081" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.23]) by orsmga006.jf.intel.com with ESMTP; 01 Apr 2020 18:42:26 -0700 From: "Huang\, Ying" To: Andrew Morton Cc: , , Andrea Arcangeli , "Kirill A . Shutemov" , Zi Yan , Vlastimil Babka , Alexey Dobriyan , Michal Hocko , Konstantin Khlebnikov , jglisse@redhat.com, Yang Shi Subject: Re: [PATCH] /proc/PID/smaps: Add PMD migration entry parsing References: <20200331085604.1260162-1-ying.huang@intel.com> <20200401160432.855bba5b210c7b4bbf6c56ef@linux-foundation.org> Date: Thu, 02 Apr 2020 09:42:26 +0800 In-Reply-To: <20200401160432.855bba5b210c7b4bbf6c56ef@linux-foundation.org> (Andrew Morton's message of "Wed, 1 Apr 2020 16:04:32 -0700") Message-ID: <87h7y2hddp.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: > 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. OK. >> --- 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. Yes. Will change this in the next version. Best Regards, Huang, Ying >> + 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; >> }