From patchwork Sat Feb 1 03:40:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11360905 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B49B714E3 for ; Sat, 1 Feb 2020 03:41:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 942DE207FD for ; Sat, 1 Feb 2020 03:41:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="CstSCBta" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727379AbgBADlQ (ORCPT ); Fri, 31 Jan 2020 22:41:16 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:11606 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727077AbgBADkj (ORCPT ); Fri, 31 Jan 2020 22:40:39 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 31 Jan 2020 19:40:24 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Fri, 31 Jan 2020 19:40:38 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Fri, 31 Jan 2020 19:40:38 -0800 Received: from HQMAIL107.nvidia.com (172.20.187.13) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sat, 1 Feb 2020 03:40:38 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Sat, 1 Feb 2020 03:40:37 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Fri, 31 Jan 2020 19:40:37 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Christoph Hellwig , Dan Williams , Dave Chinner , Ira Weiny , Jan Kara , Jason Gunthorpe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , "Kirill A . Shutemov" , Michal Hocko , Mike Kravetz , Shuah Khan , Vlastimil Babka , Matthew Wilcox , , , , , , LKML , John Hubbard Subject: [PATCH v3 09/12] mm: dump_page(): better diagnostics for huge pinned pages Date: Fri, 31 Jan 2020 19:40:26 -0800 Message-ID: <20200201034029.4063170-10-jhubbard@nvidia.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200201034029.4063170-1-jhubbard@nvidia.com> References: <20200201034029.4063170-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1580528424; bh=k4Lbk4kPcODis1gm7X0/Em7BXZ40lVe6B2OXrxTo0YE=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=CstSCBtaMdshz751Y+6zyEuqFPOdMiySa25N4tSA2A8xzcSnMUbrSM1nP1k8Jno6b r8e60UJQg8pMT+4iEDfYjRC7+J00rG0l9dJwTpeTlpZ40r1UwWubH8tl1rv4qABHxH MX81T4f1eAAnsYvG9LSjNSI26z/gcGbWWnmp8ZoVCsihWAUah2U7cRntKLM3ho3ihw 5wi5y78PFBq5AVMJACBKrrJCl8javfHKonWrtBNqOk1JqVXe+xHcrMmVbLunOMa3SG zG04DwYY3PYXgCAhvc21H5mOl5XYeDy51sR0SoySoM6gIGwHlPNhcmxmXlQqI7JzMN ZRSB7m9kArOpg== Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org As part of pin_user_pages() and related API calls, pages are "dma-pinned". For the case of compound pages of order > 1, the per-page accounting of dma pins is accomplished via the 3rd struct page in the compound page. In order to support debugging of any pin_user_pages()- related problems, enhance dump_page() so as to report the pin count in that case. Documentation/core-api/pin_user_pages.rst is also updated accordingly. Signed-off-by: John Hubbard Acked-by: Kirill A. Shutemov Reviewed-by: Jan Kara --- Documentation/core-api/pin_user_pages.rst | 7 +++++ mm/debug.c | 34 +++++++++++++++++------ 2 files changed, 33 insertions(+), 8 deletions(-) diff --git a/Documentation/core-api/pin_user_pages.rst b/Documentation/core-api/pin_user_pages.rst index 3f72b1ea1104..dd21ea140ef4 100644 --- a/Documentation/core-api/pin_user_pages.rst +++ b/Documentation/core-api/pin_user_pages.rst @@ -215,6 +215,13 @@ Those are both going to show zero, unless CONFIG_DEBUG_VM is set. This is because there is a noticeable performance drop in unpin_user_page(), when they are activated. +Other diagnostics +================= + +dump_page() has been enhanced slightly, to handle these new counting fields, and +to better report on compound pages in general. Specifically, for compound pages +with order > 1, the exact (hpage_pinned_refcount) pincount is reported. + References ========== diff --git a/mm/debug.c b/mm/debug.c index beb1c59d784b..db81b11345be 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -57,10 +57,20 @@ static void __dump_tail_page(struct page *page, int mapcount) page, page_ref_count(page), mapcount, page->mapping, page_to_pgoff(page)); } else { - pr_warn("page:%px compound refcount:%d mapcount:%d mapping:%px " - "index:%#lx compound_mapcount:%d\n", - page, page_ref_count(head), mapcount, head->mapping, - page_to_pgoff(head), compound_mapcount(page)); + if (hpage_pincount_available(page)) + pr_warn("page:%px compound refcount:%d mapcount:%d " + "mapping:%px index:%#lx compound_mapcount:%d " + "compound_pincount:%d\n", + page, page_ref_count(head), mapcount, + head->mapping, page_to_pgoff(head), + compound_mapcount(page), + compound_pincount(page)); + else + pr_warn("page:%px compound refcount:%d mapcount:%d " + "mapping:%px index:%#lx compound_mapcount:%d\n", + page, page_ref_count(head), mapcount, + head->mapping, page_to_pgoff(head), + compound_mapcount(page)); } if (page_ref_count(page) != 0) @@ -103,10 +113,18 @@ void __dump_page(struct page *page, const char *reason) if (PageTail(page)) __dump_tail_page(page, mapcount); - else - pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n", - page, page_ref_count(page), mapcount, - page->mapping, page_to_pgoff(page)); + else { + if (hpage_pincount_available(page)) + pr_warn("page:%px refcount:%d mapcount:%d mapping:%px " + "index:%#lx compound pincount: %d\n", + page, page_ref_count(page), mapcount, + page->mapping, page_to_pgoff(page), + compound_pincount(page)); + else + pr_warn("page:%px refcount:%d mapcount:%d mapping:%px " + "index:%#lx\n", page, page_ref_count(page), + mapcount, page->mapping, page_to_pgoff(page)); + } if (PageKsm(page)) type = "ksm "; else if (PageAnon(page))