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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,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 B2754C433E9 for ; Thu, 3 Sep 2020 16:56:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 74CBE208B3 for ; Thu, 3 Sep 2020 16:56:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74CBE208B3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 24A8D900003; Thu, 3 Sep 2020 12:56:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 21FBA6B005D; Thu, 3 Sep 2020 12:56:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10E44900003; Thu, 3 Sep 2020 12:56:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0190.hostedemail.com [216.40.44.190]) by kanga.kvack.org (Postfix) with ESMTP id EE0386B005C for ; Thu, 3 Sep 2020 12:56:37 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id ABF8B1E11 for ; Thu, 3 Sep 2020 16:56:37 +0000 (UTC) X-FDA: 77222354034.05.crime17_0209b14270ab Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 818131826B6B2 for ; Thu, 3 Sep 2020 16:56:37 +0000 (UTC) X-HE-Tag: crime17_0209b14270ab X-Filterd-Recvd-Size: 3496 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Sep 2020 16:56:37 +0000 (UTC) Received: from gaia (unknown [46.69.195.48]) (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 CF3B9206A5; Thu, 3 Sep 2020 16:56:34 +0000 (UTC) Date: Thu, 3 Sep 2020 17:56:32 +0100 From: Catalin Marinas To: Anshuman Khandual Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, will@kernel.org, akpm@linux-foundation.org, Mark Rutland , Marc Zyngier , Suzuki Poulose , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] arm64/mm: Change THP helpers to comply with generic MM semantics Message-ID: <20200903165631.GC31409@gaia> References: <1597655984-15428-1-git-send-email-anshuman.khandual@arm.com> <1597655984-15428-2-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1597655984-15428-2-git-send-email-anshuman.khandual@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: 818131826B6B2 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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 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 > + * 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()? 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 -- Catalin