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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 95CEDC43331 for ; Fri, 3 Apr 2020 12:31:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 649912077D for ; Fri, 3 Apr 2020 12:31:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403960AbgDCMby (ORCPT ); Fri, 3 Apr 2020 08:31:54 -0400 Received: from mga17.intel.com ([192.55.52.151]:45126 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727882AbgDCMby (ORCPT ); Fri, 3 Apr 2020 08:31:54 -0400 IronPort-SDR: 1ZiUU/T8QvcGMAzWD/6Af5WpOiQ1rqsgCFAQjgjwM75ghBeqrXFms+lN/5YX12kWSgp2gKzbRT gkmVxH+P+BIA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Apr 2020 05:31:53 -0700 IronPort-SDR: nI2olLeXrFo1lRBhvElCdhDMR3vtppxqaBq/NacGGUrVv6B7DI8vpIsFPJ7Rq3yQb2ITRGkori D5E/TseIovkQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,339,1580803200"; d="scan'208";a="273934294" Received: from unknown (HELO yhuang-dev.sh.intel.com) ([10.239.159.23]) by fmsmga004.fm.intel.com with ESMTP; 03 Apr 2020 05:31:50 -0700 From: "Huang, Ying" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Zi Yan , Andrea Arcangeli , "Kirill A . Shutemov" , Vlastimil Babka , Alexey Dobriyan , Michal Hocko , Konstantin Khlebnikov , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Yang Shi Subject: [PATCH -V3] /proc/PID/smaps: Add PMD migration entry parsing Date: Fri, 3 Apr 2020 20:30:59 +0800 Message-Id: <20200403123059.1846960-1-ying.huang@intel.com> X-Mailer: git-send-email 2.25.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. To test the patch, we run pmbench to eat 400 MB memory in background, then run /usr/bin/migratepages and `cat /proc/PID/smaps` every second. The issue as follows can be reproduced within 60 seconds. Before the patch, for the fully populated 400 MB anonymous VMA, some THP pages under migration may be lost as below. 7f3f6a7e5000-7f3f837e5000 rw-p 00000000 00:00 0 Size: 409600 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 407552 kB Pss: 407552 kB Shared_Clean: 0 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 407552 kB Referenced: 301056 kB Anonymous: 407552 kB LazyFree: 0 kB AnonHugePages: 405504 kB ShmemPmdMapped: 0 kB FilePmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB Locked: 0 kB THPeligible: 1 VmFlags: rd wr mr mw me ac After the patch, it will be always, 7f3f6a7e5000-7f3f837e5000 rw-p 00000000 00:00 0 Size: 409600 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 409600 kB Pss: 409600 kB Shared_Clean: 0 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 409600 kB Referenced: 294912 kB Anonymous: 409600 kB LazyFree: 0 kB AnonHugePages: 407552 kB ShmemPmdMapped: 0 kB FilePmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB Locked: 0 kB THPeligible: 1 VmFlags: rd wr mr mw me ac Signed-off-by: "Huang, Ying" Reviewed-by: Zi Yan Cc: Andrea Arcangeli Cc: Kirill A. Shutemov Cc: Vlastimil Babka Cc: Alexey Dobriyan Cc: Michal Hocko Cc: Konstantin Khlebnikov Cc: "Jérôme Glisse" Cc: Yang Shi --- v3: - Revised patch description and remove VM_WARN_ON_ONCE() per Michal's comments v2: - Use thp_migration_supported() in condition to reduce code size if THP migration isn't enabled. - Replace VM_BUG_ON() with VM_WARN_ON_ONCE(), it's not necessary to nuking kernel for this. --- fs/proc/task_mmu.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 8d382d4ec067..36dc7417c0df 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -546,10 +546,17 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, struct mem_size_stats *mss = walk->private; struct vm_area_struct *vma = walk->vma; bool locked = !!(vma->vm_flags & VM_LOCKED); - struct page *page; + struct page *page = NULL; + + 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(thp_migration_supported() && is_swap_pmd(*pmd))) { + swp_entry_t entry = pmd_to_swp_entry(*pmd); - /* FOLL_DUMP will return -EFAULT on huge zero page */ - page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP); + if (is_migration_entry(entry)) + page = migration_entry_to_page(entry); + } if (IS_ERR_OR_NULL(page)) return; if (PageAnon(page)) @@ -578,8 +585,7 @@ 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; } -- 2.25.0