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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 A7BE4C433F5 for ; Thu, 9 Sep 2021 01:10:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E2216115B for ; Thu, 9 Sep 2021 01:10:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348749AbhIIBLM (ORCPT ); Wed, 8 Sep 2021 21:11:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:60346 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232144AbhIIBLL (ORCPT ); Wed, 8 Sep 2021 21:11:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 16B4E6113C; Thu, 9 Sep 2021 01:10:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1631149803; bh=PJ4NEu+MkoH6d2xqP5XNeV8XRIRgMGM90hfwQfpLDAk=; h=Date:From:To:Subject:In-Reply-To:From; b=rycjUxSUm5zP0JhlJWXH5LLGMBz0jzUi2rEv6UjN5l0juF7aqix4aVT00Lj94r0XW rf8x91UFa/mMR8bOYVsrqL1jgrla9DQO8eYqajVp8nQfM1wQGTGRgxiy/j8bJ+sn3o LIUfI7MLArsSuND7TXlLxmiQFWSqV53aup+kNSqU= Date: Wed, 08 Sep 2021 18:10:02 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hch@lst.de, jgg@nvidia.com, linux-mm@kvack.org, lizhijian@cn.fujitsu.com, mm-commits@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 1/8] mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled Message-ID: <20210909011002.YtOxlcd0s%akpm@linux-foundation.org> In-Reply-To: <20210908180859.d523d4bb4ad8eec11c61500d@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Li Zhijian Subject: mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled 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 Link: https://lkml.kernel.org/r/20210830094232.203029-1-lizhijian@cn.fujitsu.com Fixes: 405506274922 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling") Signed-off-by: Li Zhijian Reviewed-by: Christoph Hellwig Reviewed-by: Jason Gunthorpe Cc: Signed-off-by: Andrew Morton --- mm/hmm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/hmm.c~mm-hmm-bypass-devmap-pte-when-all-pfn-requested-flags-are-fulfilled +++ a/mm/hmm.c @@ -295,10 +295,13 @@ static int hmm_vma_handle_pte(struct mm_ 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; _