From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757879AbcLUHvW (ORCPT ); Wed, 21 Dec 2016 02:51:22 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35069 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755501AbcLUHvT (ORCPT ); Wed, 21 Dec 2016 02:51:19 -0500 Date: Wed, 21 Dec 2016 08:51:16 +0100 From: Michal Hocko To: Wei Yang Cc: 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: <20161221075115.GE16502@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161220164823.GB13224@vultr.guest> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > >> > >> if (nid != NUMA_NO_NODE) { > >> alloc = memblock_find_in_range_node(size, align, min_addr, > >> max_addr, NUMA_NO_NODE, > >> flags); > >> - if (alloc) > >> + if (alloc && !memblock_reserve(alloc, size)) > >> goto done; > >> } > > > >This doesn't look right. You can end up leaking the first allocated > >range. > > > > Hmm... why? > > If first memblock_reserve() succeed, it will jump to done, so that no 2nd > allocation. > If the second executes, it means the first allocation failed. > memblock_find_in_range_node() doesn't modify the memblock, it just tell you > there is a proper memory region available. yes, my bad. I have missed this. Sorry about the confusion. -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f200.google.com (mail-wj0-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 031266B037D for ; Wed, 21 Dec 2016 02:51:19 -0500 (EST) Received: by mail-wj0-f200.google.com with SMTP id hb5so57893348wjc.2 for ; Tue, 20 Dec 2016 23:51:18 -0800 (PST) Received: from mail-wm0-f67.google.com (mail-wm0-f67.google.com. [74.125.82.67]) by mx.google.com with ESMTPS id n1si22766972wme.119.2016.12.20.23.51.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Dec 2016 23:51:17 -0800 (PST) Received: by mail-wm0-f67.google.com with SMTP id m203so28800119wma.3 for ; Tue, 20 Dec 2016 23:51:17 -0800 (PST) Date: Wed, 21 Dec 2016 08:51:16 +0100 From: Michal Hocko Subject: Re: [PATCH V2 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc_internal() Message-ID: <20161221075115.GE16502@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161220164823.GB13224@vultr.guest> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Yang Cc: trivial@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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? > >> > >> if (nid != NUMA_NO_NODE) { > >> alloc = memblock_find_in_range_node(size, align, min_addr, > >> max_addr, NUMA_NO_NODE, > >> flags); > >> - if (alloc) > >> + if (alloc && !memblock_reserve(alloc, size)) > >> goto done; > >> } > > > >This doesn't look right. You can end up leaking the first allocated > >range. > > > > Hmm... why? > > If first memblock_reserve() succeed, it will jump to done, so that no 2nd > allocation. > If the second executes, it means the first allocation failed. > memblock_find_in_range_node() doesn't modify the memblock, it just tell you > there is a proper memory region available. yes, my bad. I have missed this. Sorry about the confusion. -- Michal Hocko SUSE Labs -- 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