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Thu, 3 Sep 2020 17:31:47 +0000 (UTC) X-HE-Tag: feast23_1f0a051270ab X-Filterd-Recvd-Size: 4082 Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Sep 2020 17:31:47 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 03 Sep 2020 10:31:32 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 03 Sep 2020 10:31:46 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 03 Sep 2020 10:31:46 -0700 Received: from rcampbell-dev.nvidia.com (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 3 Sep 2020 17:31:45 +0000 Subject: Re: [PATCH 1/2] arm64/mm: Change THP helpers to comply with generic MM semantics To: Catalin Marinas , Anshuman Khandual CC: , , , , Mark Rutland , Marc Zyngier , Suzuki Poulose , 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: Ralph Campbell X-Nvconfidentiality: public Message-ID: <5e148194-58c2-89c2-2cd8-9f2086f1e090@nvidia.com> Date: Thu, 3 Sep 2020 10:31:44 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200903165631.GC31409@gaia> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1599154292; bh=f2fM2vwocWZ3kjufXMQxbdqVic6XFgHZzhjDyCnkunM=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=QNI5HP0mnE11hwdtt//Zo7KAtHH9mutFkC4v29SLNtD3RB0sKvljOyjJnoPg+nCNM g+qnLvvVo8HmZ/lXWGqm0dCvXsip0qT67hm2Pi5MyMMb9CeerPM3SMY1oBZWFU+GLi iDyu+m1RiBar/mNEX68xxKokJtsOiKYauiJaX5OpW5taL58vgmY+vUh/oPN/eVXnZr r2yFhkOEOz1gESPASBuELH47vVnksoAmeTIpU8qRKYseB7Ky2Jj9MQZDLq/lb7VWla m5aCR0YsGQSuBd26pUDXoM3Ji2XbK+mMbD797bTL+BujGtVTSA4uXS6c5OA64PUjX/ 0nR2261UeRJRw== X-Rspamd-Queue-Id: E69D618038E6C X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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 9/3/20 9:56 AM, 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()). > >> 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 Another nit: "This help indicate" => "This helper indicates" Maybe I should look at the series more. :-)