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=-21.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 9ABA2C432BE for ; Sat, 28 Aug 2021 01:00:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F3E260FD9 for ; Sat, 28 Aug 2021 01:00:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232936AbhH1BAr (ORCPT ); Fri, 27 Aug 2021 21:00:47 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:47504 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S232693AbhH1BAo (ORCPT ); Fri, 27 Aug 2021 21:00:44 -0400 IronPort-HdrOrdr: =?us-ascii?q?A9a23=3AEQLKFazEJguRdXz/ox3XKrPwEL1zdoMgy1kn?= =?us-ascii?q?xilNoH1uA6ilfqWV8cjzuiWbtN9vYhsdcLy7WZVoIkmskKKdg7NhXotKNTOO0A?= =?us-ascii?q?SVxepZnOnfKlPbexHWx6p00KdMV+xEAsTsMF4St63HyTj9P9E+4NTvysyVuds?= =?us-ascii?q?=3D?= X-IronPort-AV: E=Sophos;i="5.84,358,1620662400"; d="scan'208";a="113590778" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 28 Aug 2021 08:59:53 +0800 Received: from G08CNEXMBPEKD06.g08.fujitsu.local (unknown [10.167.33.206]) by cn.fujitsu.com (Postfix) with ESMTP id 33F9B4D0D4BC; Sat, 28 Aug 2021 08:59:52 +0800 (CST) Received: from G08CNEXJMPEKD02.g08.fujitsu.local (10.167.33.202) by G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Sat, 28 Aug 2021 08:59:51 +0800 Received: from G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.85) by G08CNEXJMPEKD02.g08.fujitsu.local (10.167.33.202) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Sat, 28 Aug 2021 08:59:52 +0800 Received: from localhost.localdomain (10.167.225.141) by G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.209) with Microsoft SMTP Server id 15.0.1497.23 via Frontend Transport; Sat, 28 Aug 2021 08:59:50 +0800 From: Li Zhijian To: , , , , , CC: , , Li Zhijian , Subject: [PATCH v2] mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled Date: Sat, 28 Aug 2021 09:04:41 +0800 Message-ID: <20210828010441.3702-1-lizhijian@cn.fujitsu.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-yoursite-MailScanner-ID: 33F9B4D0D4BC.AE3AF X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: lizhijian@fujitsu.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Previously, we noticed the one rpma example was failed[1] since 36f30e486d, where it will use ODP feature to do RDMA WRITE between fsdax files. After digging into the code, we found hmm_vma_handle_pte() will still return EFAULT even though all the its requesting flags has been fulfilled. That's because a DAX page will be marked as (_PAGE_SPECIAL | PAGE_DEVMAP) by pte_mkdevmap(). [1]: https://github.com/pmem/rpma/issues/1142 CC: stable@vger.kernel.org Fixes: 405506274922 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling") Signed-off-by: Li Zhijian --- mm/hmm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/hmm.c b/mm/hmm.c index fad6be2bf072..d324fb1a5352 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -295,10 +295,13 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, goto fault; /* + * Bypass devmap pte such as DAX page when all pfn requested + * flags(pfn_req_flags) are fulfilled. * Since each architecture defines a struct page for the zero page, just * fall through and treat it like a normal page. */ - if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) { + if (!pte_devmap(pte) && pte_special(pte) && + !is_zero_pfn(pte_pfn(pte))) { if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) { pte_unmap(ptep); return -EFAULT; -- 2.31.1