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=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 DACD6C432BE for ; Mon, 30 Aug 2021 09:37:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE47161039 for ; Mon, 30 Aug 2021 09:37:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235983AbhH3Jis (ORCPT ); Mon, 30 Aug 2021 05:38:48 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:13351 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S235618AbhH3Jir (ORCPT ); Mon, 30 Aug 2021 05:38:47 -0400 IronPort-HdrOrdr: =?us-ascii?q?A9a23=3AA0PzNKx7ks14I/NMf67UKrPwPb1zdoMgy1kn?= =?us-ascii?q?xilNoH1uE/Bw8vrE9sjzuiWE6wr5J0tQ++xoVJPsfZq+z/BICOsqXYtKNTOO0F?= =?us-ascii?q?dAR7sM0WKN+VHd8iTFh4tg6Zs=3D?= X-IronPort-AV: E=Sophos;i="5.84,363,1620662400"; d="scan'208";a="113710097" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 30 Aug 2021 17:37:52 +0800 Received: from G08CNEXMBPEKD04.g08.fujitsu.local (unknown [10.167.33.201]) by cn.fujitsu.com (Postfix) with ESMTP id 0E9BE4D0DC65; Mon, 30 Aug 2021 17:37:49 +0800 (CST) Received: from G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.85) by G08CNEXMBPEKD04.g08.fujitsu.local (10.167.33.201) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Mon, 30 Aug 2021 17:37:45 +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; Mon, 30 Aug 2021 17:37:42 +0800 From: Li Zhijian To: , , , , , CC: , , Li Zhijian , Subject: [PATCH v3] mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled Date: Mon, 30 Aug 2021 17:42:32 +0800 Message-ID: <20210830094232.203029-1-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: 0E9BE4D0DC65.AFF69 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: lizhijian@fujitsu.com Precedence: bulk List-ID: X-Mailing-List: stable@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 --- V3: adjust the checking order --- mm/hmm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/hmm.c b/mm/hmm.c index fad6be2bf072..842e26599238 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_special(pte) && !pte_devmap(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