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=-8.2 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_SANE_1 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 F2CD6C432C2 for ; Thu, 26 Sep 2019 00:35:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C0F08222CB for ; Thu, 26 Sep 2019 00:35:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0F08222CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5DBCF6B0010; Wed, 25 Sep 2019 20:35:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 58B1D6B0266; Wed, 25 Sep 2019 20:35:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4A2166B0269; Wed, 25 Sep 2019 20:35:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0107.hostedemail.com [216.40.44.107]) by kanga.kvack.org (Postfix) with ESMTP id 28AD16B0010 for ; Wed, 25 Sep 2019 20:35:51 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 7D77F180AD802 for ; Thu, 26 Sep 2019 00:35:50 +0000 (UTC) X-FDA: 75975204060.30.jump04_15d268adaa34a X-HE-Tag: jump04_15d268adaa34a X-Filterd-Recvd-Size: 3358 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Thu, 26 Sep 2019 00:35:49 +0000 (UTC) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Sep 2019 17:35:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,549,1559545200"; d="scan'208";a="389424398" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga005.fm.intel.com with ESMTP; 25 Sep 2019 17:35:46 -0700 Date: Thu, 26 Sep 2019 08:35:28 +0800 From: Wei Yang To: Mike Kravetz Cc: Wei Yang , akpm@linux-foundation.org, aarcange@redhat.com, hughd@google.com, linux-mm@kvack.org Subject: Re: [PATCH 1/2] userfaultfd: remove one unnecessary warn_on in __mcopy_atomic_hugetlb Message-ID: <20190926003528.GA3162@richard> Reply-To: Wei Yang References: <20190925121833.2766-1-richardw.yang@linux.intel.com> <3f69dc19-eb3b-ed46-62bc-c5e6e89ab6eb@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3f69dc19-eb3b-ed46-62bc-c5e6e89ab6eb@oracle.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Sep 25, 2019 at 10:44:58AM -0700, Mike Kravetz wrote: >On 9/25/19 5:18 AM, Wei Yang wrote: >> The warning here is to make sure address(dst_addr) and length(len - >> copied) are huge page size aligned. >> >> While this is ensured by: >> >> dst_start and len is huge page size aligned >> dst_addr equals to dst_start and increase huge page size each time >> copied increase huge page size each time > >Can we also remove the following for the same reasons? > >diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c >index 640ff2bd9a69..f82d5ec698d8 100644 >--- a/mm/userfaultfd.c >+++ b/mm/userfaultfd.c >@@ -262,7 +262,6 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, > pte_t dst_pteval; > > BUG_ON(dst_addr >= dst_start + len); >- VM_BUG_ON(dst_addr & ~huge_page_mask(h)); > Thanks for your comment. It looks good, while I lack some knowledge between vma_hpagesize and huge_page_mask(). If they are the same, why not use the same interface for all those checks in this function? > /* > * Serialize via hugetlb_fault_mutex > >-- >Mike Kravetz > >> >> This means this warning will never be triggered. >> >> Signed-off-by: Wei Yang >> --- >> mm/userfaultfd.c | 4 ---- >> 1 file changed, 4 deletions(-) >> >> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c >> index c7ae74ce5ff3..7895c715000e 100644 >> --- a/mm/userfaultfd.c >> +++ b/mm/userfaultfd.c >> @@ -243,10 +243,6 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, >> vm_shared = dst_vma->vm_flags & VM_SHARED; >> } >> >> - if (WARN_ON(dst_addr & (vma_hpagesize - 1) || >> - (len - copied) & (vma_hpagesize - 1))) >> - goto out_unlock; >> - >> /* >> * If not shared, ensure the dst_vma has a anon_vma. >> */ >> -- Wei Yang Help you, Help me