From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id E22ED6B7403 for ; Wed, 5 Dec 2018 06:15:16 -0500 (EST) Received: by mail-ed1-f69.google.com with SMTP id e12so9682723edd.16 for ; Wed, 05 Dec 2018 03:15:16 -0800 (PST) Received: from outbound-smtp25.blacknight.com (outbound-smtp25.blacknight.com. [81.17.249.193]) by mx.google.com with ESMTPS id d12si2597087edh.283.2018.12.05.03.15.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Dec 2018 03:15:15 -0800 (PST) Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp25.blacknight.com (Postfix) with ESMTPS id EE3C0B889A for ; Wed, 5 Dec 2018 11:15:14 +0000 (GMT) Date: Wed, 5 Dec 2018 11:15:13 +0000 From: Mel Gorman Subject: Re: [PATCH 1/2] mm, pageblock: make sure pageblock won't exceed mem_sectioin Message-ID: <20181205111513.GA23260@techsingularity.net> References: <20181205091905.27727-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20181205091905.27727-1-richard.weiyang@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Yang Cc: linux-mm@kvack.org, akpm@linux-foundation.org On Wed, Dec 05, 2018 at 05:19:04PM +0800, Wei Yang wrote: > When SPARSEMEM is used, there is an indication that pageblock is not > allowed to exceed one mem_section. Current code doesn't have this > constrain explicitly. > > This patch adds this to make sure it won't. > > Signed-off-by: Wei Yang Is this even possible? This would imply that the section size is smaller than max order which would be quite a crazy selection for a sparesemem section size. A lot of assumptions on the validity of PFNs within a max-order boundary would be broken with such a section size. I'd be surprised if such a setup could even boot, let alone run. -- Mel Gorman SUSE Labs