From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id 305298E0038 for ; Wed, 9 Jan 2019 03:28:52 -0500 (EST) Received: by mail-pf1-f197.google.com with SMTP id f69so4748222pff.5 for ; Wed, 09 Jan 2019 00:28:52 -0800 (PST) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.29.96]) by mx.google.com with ESMTPS id p23si375564plo.7.2019.01.09.00.28.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Jan 2019 00:28:51 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 09 Jan 2019 13:58:50 +0530 From: Arun KS Subject: Re: [PATCH v7] mm/page_alloc.c: memory_hotplug: free pages as higher order In-Reply-To: <20190109073718.GM31793@dhcp22.suse.cz> References: <1546578076-31716-1-git-send-email-arunks@codeaurora.org> <20190108181352.GI31793@dhcp22.suse.cz> <20190109073718.GM31793@dhcp22.suse.cz> Message-ID: Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Alexander Duyck , arunks.linux@gmail.com, akpm@linux-foundation.org, vbabka@suse.cz, osalvador@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, getarunks@gmail.com On 2019-01-09 13:07, Michal Hocko wrote: > On Wed 09-01-19 11:28:52, Arun KS wrote: >> On 2019-01-08 23:43, Michal Hocko wrote: >> > On Tue 08-01-19 09:56:09, Alexander Duyck wrote: >> > > On Fri, 2019-01-04 at 10:31 +0530, Arun KS wrote: >> > [...] >> > > > static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, >> > > > void *arg) >> > > > { >> > > > - unsigned long i; >> > > > unsigned long onlined_pages = *(unsigned long *)arg; >> > > > - struct page *page; >> > > > >> > > > if (PageReserved(pfn_to_page(start_pfn))) >> > > > - for (i = 0; i < nr_pages; i++) { >> > > > - page = pfn_to_page(start_pfn + i); >> > > > - (*online_page_callback)(page); >> > > > - onlined_pages++; >> > > > - } >> > > > + onlined_pages = online_pages_blocks(start_pfn, nr_pages); >> > > >> > > Shouldn't this be a "+=" instead of an "="? It seems like you are >> > > going >> > > to lose your count otherwise. >> > >> > You are right of course. I should have noticed during the review. >> > Thanks! >> >> I think we don't need to. The caller function is setting onlined_pages >> = 0 >> before calling online_pages_range(). >> And there are no other reference to online_pages_range other than from >> online_pages(). > > Are you missing that we accumulate onlined_pages via > *(unsigned long *)arg = onlined_pages; > in online_pages_range? In my testing I didn't find any problem. To match the code being replaced and to avoid any corner cases, it is better to use += Will update the patch. Regards, Arun