Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753806AbbHSLxD (ORCPT ); Wed, 19 Aug 2015 07:53:03 -0400 Received: from mail-ig0-f177.google.com ([209.85.213.177]:36113 "EHLO mail-ig0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753318AbbHSLxA (ORCPT ); Wed, 19 Aug 2015 07:53:00 -0400 MIME-Version: 1.0 In-Reply-To: <1439781546-7217-4-git-send-email-jiang.liu@linux.intel.com> References: <1439781546-7217-1-git-send-email-jiang.liu@linux.intel.com> <1439781546-7217-4-git-send-email-jiang.liu@linux.intel.com> Date: Wed, 19 Aug 2015 06:52:59 -0500 Message-ID: Subject: Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to support memoryless node From: Robin Holt To: Jiang Liu Cc: Andrew Morton , Mel Gorman , David Rientjes , Mike Galbraith , Peter Zijlstra , "Rafael J . Wysocki" , Tang Chen , Tejun Heo , Cliff Whickman , Tony Luck , linux-mm@kvack.org, linux-hotplug@vger.kernel.org, LKML , x86@kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1788 Lines: 41 On Sun, Aug 16, 2015 at 10:19 PM, Jiang Liu wrote: > Function xpc_create_gru_mq_uv() allocates memory with __GFP_THISNODE > flag set, which may cause permanent memory allocation failure on > memoryless node. So replace cpu_to_node() with cpu_to_mem() to better > support memoryless node. For node with memory, cpu_to_mem() is the same > as cpu_to_node(). > > Signed-off-by: Jiang Liu > --- > drivers/misc/sgi-xp/xpc_uv.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c > index 95c894482fdd..9210981c0d5b 100644 > --- a/drivers/misc/sgi-xp/xpc_uv.c > +++ b/drivers/misc/sgi-xp/xpc_uv.c > @@ -238,7 +238,7 @@ xpc_create_gru_mq_uv(unsigned int mq_size, int cpu, char *irq_name, > > mq->mmr_blade = uv_cpu_to_blade_id(cpu); > > - nid = cpu_to_node(cpu); > + nid = cpu_to_mem(cpu); I would recommend rejecting this. First, SGI's UV system does not and can not support memory-less nodes. Additionally the hardware _REALLY_ wants the memory to be local to the CPU. We will register this memory region with the node firmware. That will set the hardware up to watch this memory block and raise an IRQ targeting the registered CPU when anything is written into the memory block. This is all part of how cross-partition communications expects to work. Additionally, the interrupt handler will read the memory region, so having node-local memory is extremely helpful. Thanks, Robin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/