Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753604AbbFXOeL (ORCPT ); Wed, 24 Jun 2015 10:34:11 -0400 Received: from mail-vn0-f47.google.com ([209.85.216.47]:41642 "EHLO mail-vn0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752816AbbFXOeE (ORCPT ); Wed, 24 Jun 2015 10:34:04 -0400 MIME-Version: 1.0 In-Reply-To: References: <1434894751-6877-1-git-send-email-akinobu.mita@gmail.com> <1434894751-6877-4-git-send-email-akinobu.mita@gmail.com> Date: Wed, 24 Jun 2015 23:34:03 +0900 Message-ID: Subject: Re: [PATCH 3/4] blk-mq: establish new mapping before cpu starts handling requests From: Akinobu Mita To: Ming Lei Cc: Linux Kernel Mailing List , Jens Axboe 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: 1050 Lines: 21 Hi Ming, 2015-06-24 18:46 GMT+09:00 Ming Lei : > On Sun, Jun 21, 2015 at 9:52 PM, Akinobu Mita wrote: >> ctx->index_hw is zero for the CPUs which have never been onlined since >> the block queue was initialized. If one of those CPUs is hotadded and >> starts handling request before new mappings are established, pending > > Could you explain a bit what the handling request is? The fact is that > blk_mq_queue_reinit() is run after all queues are put into freezing. Notifier callbacks for CPU_ONLINE action can be run on the other CPU than the CPU which was just onlined. So it is possible for the process running on the just onlined CPU to insert request and run hw queue before blk_mq_queue_reinit_notify() is actually called with action=CPU_ONLINE. -- 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/