From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f50.google.com (mail-wg0-f50.google.com [74.125.82.50]) by kanga.kvack.org (Postfix) with ESMTP id B64B66B0032 for ; Fri, 23 Jan 2015 12:37:12 -0500 (EST) Received: by mail-wg0-f50.google.com with SMTP id b13so8715572wgh.9 for ; Fri, 23 Jan 2015 09:37:12 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id l5si3924366wiy.6.2015.01.23.09.37.10 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Jan 2015 09:37:11 -0800 (PST) Date: Fri, 23 Jan 2015 12:36:59 -0500 From: Johannes Weiner Subject: Re: mmotm 2015-01-22-15-04: qemu failure due to 'mm: memcontrol: remove unnecessary soft limit tree node test' Message-ID: <20150123173659.GB12036@phnom.home.cmpxchg.org> References: <54c1822d.RtdGfWPekQVAw8Ly%akpm@linux-foundation.org> <20150123050802.GB22751@roeck-us.net> <20150123141817.GA22926@phnom.home.cmpxchg.org> <20150123160204.GA32592@phnom.home.cmpxchg.org> <54C27E07.6000908@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54C27E07.6000908@roeck-us.net> Sender: owner-linux-mm@kvack.org List-ID: To: Guenter Roeck Cc: Christoph Lameter , akpm@linux-foundation.org, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-next@vger.kernel.org, Stephen Rothwell , mhocko@suse.cz On Fri, Jan 23, 2015 at 08:59:51AM -0800, Guenter Roeck wrote: > On 01/23/2015 08:02 AM, Johannes Weiner wrote: > >On Fri, Jan 23, 2015 at 09:17:44AM -0600, Christoph Lameter wrote: > >>On Fri, 23 Jan 2015, Johannes Weiner wrote: > >> > >>>Is the assumption of this patch wrong? Does the specified node have > >>>to be online for the fallback to work? > >> > >>Nodes that are offline have no control structures allocated and thus > >>allocations will likely segfault when the address of the controls > >>structure for the node is accessed. > >> > >>If we wanted to prevent that then every allocation would have to add a > >>check to see if the nodes are online which would impact performance. > > > >Okay, that makes sense, thank you. > > > >Andrew, can you please drop this patch? > > > Problem is that there are three patches. > > 2537ffb mm: memcontrol: consolidate swap controller code > 2f9b346 mm: memcontrol: consolidate memory controller initialization > a40d0d2 mm: memcontrol: remove unnecessary soft limit tree node test > > Reverting (or dropping) a40d0d2 alone is not possible since it modifies > mem_cgroup_soft_limit_tree_init which is removed by 2f9b346. ("mm: memcontrol: consolidate swap controller code") gave me no issues when rebasing, but ("mm: memcontrol: consolidate memory controller initialization") needs updating. So how about this one to replace ("mm: memcontrol: remove unnecessary soft limit tree node test"): --- From: Johannes Weiner Subject: [patch] mm: memcontrol: simplify soft limit tree init code - No need to test the node for N_MEMORY. node_online() is enough for node fallback to work in slab, use NUMA_NO_NODE for everything else. - Remove the BUG_ON() for allocation failure. A NULL pointer crash is just as descriptive, and the absent return value check is obvious. - Move local variables to the inner-most blocks. - Point to the tree structure after its initialized, not before, it's just more logical that way. Signed-off-by: Johannes Weiner --- mm/memcontrol.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index fb9788af4a3e..88c67303d141 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4537,24 +4537,23 @@ EXPORT_SYMBOL(parent_mem_cgroup); static void __init mem_cgroup_soft_limit_tree_init(void) { - struct mem_cgroup_tree_per_node *rtpn; - struct mem_cgroup_tree_per_zone *rtpz; - int tmp, node, zone; + int node; for_each_node(node) { - tmp = node; - if (!node_state(node, N_NORMAL_MEMORY)) - tmp = -1; - rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp); - BUG_ON(!rtpn); + struct mem_cgroup_tree_per_node *rtpn; + int zone; - soft_limit_tree.rb_tree_per_node[node] = rtpn; + rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, + node_online(node) ? node : NUMA_NO_NODE); for (zone = 0; zone < MAX_NR_ZONES; zone++) { + struct mem_cgroup_tree_per_zone *rtpz; + rtpz = &rtpn->rb_tree_per_zone[zone]; rtpz->rb_root = RB_ROOT; spin_lock_init(&rtpz->lock); } + soft_limit_tree.rb_tree_per_node[node] = rtpn; } } -- 2.2.2 -- 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