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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 20A8CC47258 for ; Wed, 6 May 2020 07:43:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DC97E20714 for ; Wed, 6 May 2020 07:43:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="QUUm8BzZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC97E20714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 76D598E0005; Wed, 6 May 2020 03:43:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 71DAB8E0003; Wed, 6 May 2020 03:43:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 633158E0005; Wed, 6 May 2020 03:43:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0230.hostedemail.com [216.40.44.230]) by kanga.kvack.org (Postfix) with ESMTP id 478368E0003 for ; Wed, 6 May 2020 03:43:23 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id F224745B3 for ; Wed, 6 May 2020 07:43:22 +0000 (UTC) X-FDA: 76785503844.04.whip34_63154707151 X-HE-Tag: whip34_63154707151 X-Filterd-Recvd-Size: 3196 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Wed, 6 May 2020 07:43:22 +0000 (UTC) Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1F5D2206E6; Wed, 6 May 2020 07:43:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588751000; bh=CNBwwDwBOdMK1xYnzJC73BfdILtwbAZgrZjht4vqeyc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QUUm8BzZ8znSKBEEsbsVuGQDziUF1EF3dxO8+Wevy2T47Isn6Mbj360Qi8dfDWRM6 fC4aJjGy4P7u43fwidS4zRE7/mmwnuYl1NTJYv7o/rTJqRtli2t/D66lUvn+IkgD+N dqEi3vJpYxPZOSFMOjzlXG1EF17kaCVBRkm2E5zM= Date: Wed, 6 May 2020 08:43:16 +0100 From: Will Deacon To: Anshuman Khandual Cc: linux-mm@kvack.org, akpm@linux-foundation.org, Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 1/3] arm64/mm: Drop __HAVE_ARCH_HUGE_PTEP_GET Message-ID: <20200506074315.GD7021@willie-the-truck> References: <1588745534-24418-1-git-send-email-anshuman.khandual@arm.com> <1588745534-24418-2-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1588745534-24418-2-git-send-email-anshuman.khandual@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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, May 06, 2020 at 11:42:12AM +0530, Anshuman Khandual wrote: > Platform specific huge_ptep_get() is required only when fetching the huge > PTE involves more than just dereferencing the page table pointer. This is > not the case on arm64 platform. Hence huge_ptep_pte() can be dropped along > with it's __HAVE_ARCH_HUGE_PTEP_GET subscription. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Andrew Morton > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > arch/arm64/include/asm/hugetlb.h | 6 ------ > 1 file changed, 6 deletions(-) > > diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h > index 2eb6c234d594..b88878ddc88b 100644 > --- a/arch/arm64/include/asm/hugetlb.h > +++ b/arch/arm64/include/asm/hugetlb.h > @@ -17,12 +17,6 @@ > extern bool arch_hugetlb_migration_supported(struct hstate *h); > #endif > > -#define __HAVE_ARCH_HUGE_PTEP_GET > -static inline pte_t huge_ptep_get(pte_t *ptep) > -{ > - return READ_ONCE(*ptep); > -} Hmm, I'm nervous about dropping the READ_ONCE() here. We added them after running into page-table issues with THP [1] and it's really important to use them consistently to avoid hitting that again. If the generic code used READ_ONCE(), I'd be happy to switch to it. Will [1] https://lore.kernel.org/lkml/1506527369-19535-1-git-send-email-will.deacon@arm.com/