From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Date: Thu, 08 Oct 2015 20:20:37 +0000 Subject: Re: [Intel-wired-lan] [Patch V3 5/9] i40e: Use numa_mem_id() to better support memoryless node Message-Id: <20151008132037.fc3887da0818e7d011cb752f@linux-foundation.org> List-Id: References: <1439781546-7217-1-git-send-email-jiang.liu@linux.intel.com> <1439781546-7217-6-git-send-email-jiang.liu@linux.intel.com> <4197C471DCF8714FBA1FE32565271C148FFFF4D3@ORSMSX103.amr.corp.intel.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Rientjes Cc: "Patil, Kiran" , Jiang Liu , Mel Gorman , Mike Galbraith , Peter Zijlstra , "Wysocki, Rafael J" , Tang Chen , Tejun Heo , "Kirsher, Jeffrey T" , "Brandeburg, Jesse" , "Nelson, Shannon" , "Wyborny, Carolyn" , "Skidmore, Donald C" , "Vick, Matthew" , "Ronciak, John" , "Williams, Mitch A" , "Luck, Tony" , "netdev@vger.kernel.org" , "x86@kernel.org" , "linux-hotplug@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "intel-wired-lan@lists.osuosl.org" On Wed, 19 Aug 2015 17:18:15 -0700 (PDT) David Rientjes wrote: > On Wed, 19 Aug 2015, Patil, Kiran wrote: > > > Acked-by: Kiran Patil > > Where's the call to preempt_disable() to prevent kernels with preemption > from making numa_node_id() invalid during this iteration? David asked this question twice, received no answer and now the patch is in the maintainer tree, destined for mainline. If I was asked this question I would respond The use of numa_mem_id() is racy and best-effort. If the unlikely race occurs, the memory allocation will occur on the wrong node, the overall result being very slightly suboptimal performance. The existing use of numa_node_id() suffers from the same issue. But I'm not the person proposing the patch. Please don't just ignore reviewer comments!