From patchwork Thu Apr 22 06:18:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 12217713 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=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,USER_AGENT_GIT 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 6C74BC43460 for ; Thu, 22 Apr 2021 06:19:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B721061453 for ; Thu, 22 Apr 2021 06:19:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B721061453 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 51B3F6B006E; Thu, 22 Apr 2021 02:19:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4CAA46B0070; Thu, 22 Apr 2021 02:19:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 392B16B0071; Thu, 22 Apr 2021 02:19:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0139.hostedemail.com [216.40.44.139]) by kanga.kvack.org (Postfix) with ESMTP id 1D0A16B006E for ; Thu, 22 Apr 2021 02:19:17 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D2D32181B048C for ; Thu, 22 Apr 2021 06:19:16 +0000 (UTC) X-FDA: 78059000712.18.DE51A5B Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP id 0874DF0 for ; Thu, 22 Apr 2021 06:19:08 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 15B886113C; Thu, 22 Apr 2021 06:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619072355; bh=E81akF1BinjHKMvNozvRyjwjqZ1X1qBHHvRxS2i48PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uhF/ObuaXIspDxBYAAvqiR9bZWwB6AgoMlH014SLQhtOLankdq4B/GD3Yo0udRpVN V4O7zfQeYj3d3MsrkeqVdql8uSygos1lTLK7EI4LL+45XgG1WXnQAKKoqc+MSynyv8 RPTss4obNwjyO+I1nhKkRsUpm+BVzxRIOv8H69n8pyGU9MgJmnC8MVR812ygWZw88d IMPinfocfipp01RqC8gTj6sHqEEC14mHm4WBMVnRmpjfqnBGjgfwVLky+NEAH/sLGz ymht+5Lg6VmPoy5sPouM6ey44RYSp1fUy1r+DOgpc2ZVwQZt/vzKXsMWS96M//CVtD HCIHPVRr+SEcQ== From: Mike Rapoport To: linux-arm-kernel@lists.infradead.org Cc: Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Marc Zyngier , Mark Rutland , Mike Rapoport , Mike Rapoport , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 1/4] include/linux/mmzone.h: add documentation for pfn_valid() Date: Thu, 22 Apr 2021 09:18:59 +0300 Message-Id: <20210422061902.21614-2-rppt@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20210422061902.21614-1-rppt@kernel.org> References: <20210422061902.21614-1-rppt@kernel.org> MIME-Version: 1.0 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0874DF0 X-Stat-Signature: 7w395b6tnkgpp7oy9nmxfogdqd47pmqt Received-SPF: none (kernel.org>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619072348-549261 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: From: Mike Rapoport Add comment describing the semantics of pfn_valid() that clarifies that pfn_valid() only checks for availability of a memory map entry (i.e. struct page) for a PFN rather than availability of usable memory backing that PFN. The most "generic" version of pfn_valid() used by the configurations with SPARSEMEM enabled resides in include/linux/mmzone.h so this is the most suitable place for documentation about semantics of pfn_valid(). Suggested-by: Anshuman Khandual Signed-off-by: Mike Rapoport Reviewed-by: Anshuman Khandual --- include/linux/mmzone.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 47946cec7584..961f0eeefb62 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1410,6 +1410,17 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) #endif #ifndef CONFIG_HAVE_ARCH_PFN_VALID +/** + * pfn_valid - check if there is a valid memory map entry for a PFN + * @pfn: the page frame number to check + * + * Check if there is a valid memory map entry aka struct page for the @pfn. + * Note, that availability of the memory map entry does not imply that + * there is actual usable memory at that @pfn. The struct page may + * represent a hole or an unusable page frame. + * + * Return: 1 for PFNs that have memory map entries and 0 otherwise + */ static inline int pfn_valid(unsigned long pfn) { struct mem_section *ms;