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=-9.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 E4978C43461 for ; Tue, 8 Sep 2020 10:20:18 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6B69F20C09 for ; Tue, 8 Sep 2020 10:20:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="aA79czQN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B69F20C09 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jYZFmDKk1YXHzNW9do5LVWEACRxjWaXQqGkCg/2TPpo=; b=aA79czQNM/EreQQaVyO4ivRba KURXq8NrPwnhphr398H9VWMC0Lphl1L7OsfSiDZV1HOAjvUs5ck1oKDCChZN5eZqNde2WZeEkWzAT M82eee3MLD/yWWte5ebWWY4ZhOhs5ArPnoXFtl5UbylKQIMWC7szyBe5bLSrz5/VeAdhtHftuwnd8 xFHrLTZlLqHOHQ1pR8NmWWm2zuHlzZfWFrpVmp+6TgRAuqJ7s51JleVEcXx/zHkUNd6+zb5Sg9np3 aMUqENqwyKNaHlRNLzz1wsM9EQAR6PsDi/xGXyXyhBUg+xYhdXt8xiw4o9u8jaKaxUmouUzRnoHtA Cgv2SZqeg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFaiB-0008QW-1d; Tue, 08 Sep 2020 10:18:51 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFai5-0008OT-37 for linux-arm-kernel@lists.infradead.org; Tue, 08 Sep 2020 10:18:48 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B616631B; Tue, 8 Sep 2020 03:18:43 -0700 (PDT) Received: from [10.163.71.211] (unknown [10.163.71.211]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 80B453F66E; Tue, 8 Sep 2020 03:18:40 -0700 (PDT) Subject: Re: [PATCH 1/2] arm64/mm: Change THP helpers to comply with generic MM semantics To: Catalin Marinas References: <1597655984-15428-1-git-send-email-anshuman.khandual@arm.com> <1597655984-15428-2-git-send-email-anshuman.khandual@arm.com> <20200903165631.GC31409@gaia> From: Anshuman Khandual Message-ID: Date: Tue, 8 Sep 2020 15:48:08 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200903165631.GC31409@gaia> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200908_061845_230925_BD11A40D X-CRM114-Status: GOOD ( 23.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Suzuki Poulose , Marc Zyngier , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, will@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 09/03/2020 10:26 PM, Catalin Marinas wrote: > On Mon, Aug 17, 2020 at 02:49:43PM +0530, Anshuman Khandual wrote: >> pmd_present() and pmd_trans_huge() are expected to behave in the following >> manner during various phases of a given PMD. It is derived from a previous >> detailed discussion on this topic [1] and present THP documentation [2]. >> >> pmd_present(pmd): >> >> - Returns true if pmd refers to system RAM with a valid pmd_page(pmd) >> - Returns false if pmd does not refer to system RAM - Invalid pmd_page(pmd) > > The second bullet doesn't make much sense. If you have a pmd mapping of > some I/O memory, pmd_present() still returns true (as does > pte_present()). Derived this from an earlier discussion (https://lkml.org/lkml/2018/10/17/231) but current representation here might not be accurate. Would this be any better ? pmd_present(pmd): - Returns true if pmd refers to system RAM with a valid pmd_page(pmd) - Returns false if pmd refers to a migration or swap entry > >> diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h >> index 4d867c6446c4..28792fdd9627 100644 >> --- a/arch/arm64/include/asm/pgtable-prot.h >> +++ b/arch/arm64/include/asm/pgtable-prot.h >> @@ -19,6 +19,13 @@ >> #define PTE_DEVMAP (_AT(pteval_t, 1) << 57) >> #define PTE_PROT_NONE (_AT(pteval_t, 1) << 58) /* only when !PTE_VALID */ >> >> +/* >> + * This help indicate that the entry is present i.e pmd_page() > > Nit: add another . after i.e Will fix. > >> + * still points to a valid huge page in memory even if the pmd >> + * has been invalidated. >> + */ >> +#define PMD_PRESENT_INVALID (_AT(pteval_t, 1) << 59) /* only when !PMD_SECT_VALID */ >> + >> #ifndef __ASSEMBLY__ >> >> #include >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >> index d5d3fbe73953..7aa69cace784 100644 >> --- a/arch/arm64/include/asm/pgtable.h >> +++ b/arch/arm64/include/asm/pgtable.h >> @@ -145,6 +145,18 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot) >> return pte; >> } >> >> +static inline pmd_t clr_pmd_bit(pmd_t pmd, pgprot_t prot) >> +{ >> + pmd_val(pmd) &= ~pgprot_val(prot); >> + return pmd; >> +} > > Could you use clear_pmd_bit (instead of clr) for consistency with > clear_pte_bit()? Sure, will do. > > It would be good if the mm folk can do a sanity check on the assumptions > about pmd_present/pmdp_invalidate/pmd_trans_huge. > > The patch looks fine to me otherwise, feel free to add: > > Reviewed-by: Catalin Marinas > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel