From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936166AbcLUOkC (ORCPT ); Wed, 21 Dec 2016 09:40:02 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:33087 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935148AbcLUOj7 (ORCPT ); Wed, 21 Dec 2016 09:39:59 -0500 Date: Wed, 21 Dec 2016 14:39:56 +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 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc_internal() Message-ID: <20161221143956.GA23331@vultr.guest> Reply-To: Wei Yang References: <1482072470-26151-1-git-send-email-richard.weiyang@gmail.com> <1482072470-26151-3-git-send-email-richard.weiyang@gmail.com> <20161219152156.GC5175@dhcp22.suse.cz> <20161220164823.GB13224@vultr.guest> <20161221075115.GE16502@dhcp22.suse.cz> <20161221131332.GB23096@vultr.guest> <20161221132200.GK31118@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161221132200.GK31118@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 On Wed, Dec 21, 2016 at 02:22:01PM +0100, Michal Hocko wrote: >On Wed 21-12-16 13:13:32, Wei Yang wrote: >> On Wed, Dec 21, 2016 at 08:51:16AM +0100, Michal Hocko wrote: >> >On Tue 20-12-16 16:48:23, Wei Yang wrote: >> >> On Mon, Dec 19, 2016 at 04:21:57PM +0100, Michal Hocko wrote: >> >> >On Sun 18-12-16 14:47:50, Wei Yang wrote: >> >> >> memblock_reserve() may fail in case there is not enough regions. >> >> > >> >> >Have you seen this happenning in the real setups or this is a by-review >> >> >driven change? >> >> >> >> This is a by-review driven change. >> >> >> >> >[...] >> >> >> again: >> >> >> alloc = memblock_find_in_range_node(size, align, min_addr, max_addr, >> >> >> nid, flags); >> >> >> - if (alloc) >> >> >> + if (alloc && !memblock_reserve(alloc, size)) >> >> >> goto done; >> > >> >So how exactly does the reserve fail when memblock_find_in_range_node >> >found a suitable range for the given size? >> > >> >> Even memblock_find_in_range_node() gets a suitable range, memblock_reserve() >> still could fail. And the case just happens when memblock can't resize. >> memblock_reserve() reserve a range by adding a range to memblock.reserved. In >> case the memblock.reserved is full and can't resize, this fails. > >Sorry for being dense but what does it mean that the reserved will get >full? Also how probable is such a situation? Is it even real? In other >words does this fix a real or only a theoretical problem? > This is a theoretical problem. While if happens, it is hard to detect. Future allocator will think this range is still available. >Anyway this all should be part of the changelog. Ok, let me add this in changelog in next version. >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id D554A6B03A9 for ; Wed, 21 Dec 2016 09:39:59 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id 83so320105345pfx.1 for ; Wed, 21 Dec 2016 06:39:59 -0800 (PST) Received: from mail-pg0-x244.google.com (mail-pg0-x244.google.com. [2607:f8b0:400e:c05::244]) by mx.google.com with ESMTPS id h5si26918124pgg.22.2016.12.21.06.39.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Dec 2016 06:39:58 -0800 (PST) Received: by mail-pg0-x244.google.com with SMTP id b1so16517414pgc.1 for ; Wed, 21 Dec 2016 06:39:58 -0800 (PST) Date: Wed, 21 Dec 2016 14:39:56 +0000 From: Wei Yang Subject: Re: [PATCH V2 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc_internal() Message-ID: <20161221143956.GA23331@vultr.guest> Reply-To: Wei Yang References: <1482072470-26151-1-git-send-email-richard.weiyang@gmail.com> <1482072470-26151-3-git-send-email-richard.weiyang@gmail.com> <20161219152156.GC5175@dhcp22.suse.cz> <20161220164823.GB13224@vultr.guest> <20161221075115.GE16502@dhcp22.suse.cz> <20161221131332.GB23096@vultr.guest> <20161221132200.GK31118@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161221132200.GK31118@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Wei Yang , trivial@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Dec 21, 2016 at 02:22:01PM +0100, Michal Hocko wrote: >On Wed 21-12-16 13:13:32, Wei Yang wrote: >> On Wed, Dec 21, 2016 at 08:51:16AM +0100, Michal Hocko wrote: >> >On Tue 20-12-16 16:48:23, Wei Yang wrote: >> >> On Mon, Dec 19, 2016 at 04:21:57PM +0100, Michal Hocko wrote: >> >> >On Sun 18-12-16 14:47:50, Wei Yang wrote: >> >> >> memblock_reserve() may fail in case there is not enough regions. >> >> > >> >> >Have you seen this happenning in the real setups or this is a by-review >> >> >driven change? >> >> >> >> This is a by-review driven change. >> >> >> >> >[...] >> >> >> again: >> >> >> alloc = memblock_find_in_range_node(size, align, min_addr, max_addr, >> >> >> nid, flags); >> >> >> - if (alloc) >> >> >> + if (alloc && !memblock_reserve(alloc, size)) >> >> >> goto done; >> > >> >So how exactly does the reserve fail when memblock_find_in_range_node >> >found a suitable range for the given size? >> > >> >> Even memblock_find_in_range_node() gets a suitable range, memblock_reserve() >> still could fail. And the case just happens when memblock can't resize. >> memblock_reserve() reserve a range by adding a range to memblock.reserved. In >> case the memblock.reserved is full and can't resize, this fails. > >Sorry for being dense but what does it mean that the reserved will get >full? Also how probable is such a situation? Is it even real? In other >words does this fix a real or only a theoretical problem? > This is a theoretical problem. While if happens, it is hard to detect. Future allocator will think this range is still available. >Anyway this all should be part of the changelog. Ok, let me add this in changelog in next version. >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org