From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id 7D90B8E0001 for ; Tue, 22 Jan 2019 01:58:22 -0500 (EST) Received: by mail-ed1-f70.google.com with SMTP id m19so8908646edc.6 for ; Mon, 21 Jan 2019 22:58:22 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id cx1-v6si2713934ejb.63.2019.01.21.22.58.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Jan 2019 22:58:21 -0800 (PST) Date: Tue, 22 Jan 2019 07:58:18 +0100 From: Michal Hocko Subject: Re: [PATCH v3] mm/hotplug: invalid PFNs from pfn_to_online_page() Message-ID: <20190122065818.GA4087@dhcp22.suse.cz> References: <20190121212747.23029-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190121212747.23029-1-cai@lca.pw> Sender: owner-linux-mm@kvack.org List-ID: To: Qian Cai Cc: akpm@linux-foundation.org, osalvador@suse.de, catalin.marinas@arm.com, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Mon 21-01-19 16:27:47, Qian Cai wrote: [...] Sorry to miss this before but you want to > +#define pfn_to_online_page(pfn) \ > +({ \ > + struct page *___page = NULL; \ unsigned long ___pfn = pfn; > + unsigned long ___nr = pfn_to_section_nr(pfn); \ pfn_to_section_nr(___pfn); > + \ > + if (___nr < NR_MEM_SECTIONS && online_section_nr(___nr) && \ > + pfn_valid_within(pfn)) \ pfn_valid_within(___pfn)) > + ___page = pfn_to_page(pfn); \ > + ___page; \ > }) to prevent from issues when pfn expression has side effects. -- Michal Hocko SUSE Labs