Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757842AbcLUNPi (ORCPT ); Wed, 21 Dec 2016 08:15:38 -0500 Received: from mail-pf0-f193.google.com ([209.85.192.193]:34416 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750976AbcLUNPf (ORCPT ); Wed, 21 Dec 2016 08:15:35 -0500 Date: Wed, 21 Dec 2016 13:15:31 +0000 From: Wei Yang To: Michal Hocko Cc: Wei Yang , trivial@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 1/2] mm/memblock.c: trivial code refine in memblock_is_region_memory() Message-ID: <20161221131531.GC23096@vultr.guest> Reply-To: Wei Yang References: <1482072470-26151-1-git-send-email-richard.weiyang@gmail.com> <1482072470-26151-2-git-send-email-richard.weiyang@gmail.com> <20161219151514.GB5175@dhcp22.suse.cz> <20161220163540.GA13224@vultr.guest> <20161221074809.GD16502@dhcp22.suse.cz> <20161221124320.GA23096@vultr.guest> <20161221124816.GJ31118@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161221124816.GJ31118@dhcp22.suse.cz> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1914 Lines: 56 On Wed, Dec 21, 2016 at 01:48:17PM +0100, Michal Hocko wrote: >On Wed 21-12-16 12:43:20, Wei Yang wrote: >> On Wed, Dec 21, 2016 at 08:48:09AM +0100, Michal Hocko wrote: >> >On Tue 20-12-16 16:35:40, Wei Yang wrote: >> >> On Mon, Dec 19, 2016 at 04:15:14PM +0100, Michal Hocko wrote: >> >> >On Sun 18-12-16 14:47:49, Wei Yang wrote: >> >> >> The base address is already guaranteed to be in the region by >> >> >> memblock_search(). >> >> > >> >> >> >> Hi, Michal >> >> >> >> Nice to receive your comment. >> >> >> >> >First of all the way how the check is removed is the worst possible... >> >> >Apart from that it is really not clear to me why checking the base >> >> >is not needed. You are mentioning memblock_search but what about other >> >> >callers? adjust_range_page_size_mask e.g... >> >> > >> >> >> >> Hmm... the memblock_search() is called by memblock_is_region_memory(). Maybe I >> >> paste the whole function here would clarify the change. >> >> >> >> int __init_memblock memblock_is_region_memory(phys_addr_t base, phys_addr_t size) >> >> { >> >> int idx = memblock_search(&memblock.memory, base); >> >> phys_addr_t end = base + memblock_cap_size(base, &size); >> >> >> >> if (idx == -1) >> >> return 0; >> >> return memblock.memory.regions[idx].base <= base && >> >> (memblock.memory.regions[idx].base + >> >> memblock.memory.regions[idx].size) >= end; >> >> } >> > >> >Ohh, my bad. I thought that memblock_search is calling >> >memblock_is_region_memory. I didn't notice this is other way around. >> >Then I agree that the check for the base is not needed and can be >> >removed. >> >> Thanks~ >> >> I would feel honored if you would like to add Acked-by :-) > >My Nack to the original patch still holds. If you want to remove the >check then remove it rather than comment it out. Got it, will send a new version. >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me