From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out002.mailprotect.be ([83.217.72.86]:37755 "EHLO out002.mailprotect.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726667AbeIIXhY (ORCPT ); Sun, 9 Sep 2018 19:37:24 -0400 Message-ID: <1536518780.23536.3.camel@acm.org> Subject: Re: [PATCH] percpu-refcount: relax limit on percpu_ref_reinit() From: Bart Van Assche To: Ming Lei , linux-kernel@vger.kernel.org Cc: Tejun Heo , Jianchao Wang , Kent Overstreet , linux-block@vger.kernel.org Date: Sun, 09 Sep 2018 11:46:20 -0700 In-Reply-To: <20180909125824.9150-1-ming.lei@redhat.com> References: <20180909125824.9150-1-ming.lei@redhat.com> Content-Type: text/plain; charset="UTF-7" Mime-Version: 1.0 Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Sun, 2018-09-09 at 20:58 +-0800, Ming Lei wrote: +AD4 Now percpu+AF8-ref+AF8-reinit() can only be done on one percpu refcounter +AD4 when it drops zero. And the limit shouldn't be so strict, and it +AD4 is quite straightforward that percpu+AF8-ref+AF8-reinit() can be done when +AD4 this counter is at atomic mode. +AD4 +AD4 This patch relaxes the limit, so we may avoid extra change+AFs-1+AF0 for NVMe +AD4 timeout's requirement. +AD4 +AD4 +AFs-1+AF0 https://marc.info/?l+AD0-linux-kernel+ACY-m+AD0-153612052611020+ACY-w+AD0-2 Is the NVMe driver the only block driver that hangs if it is attempted to freeze its request queue when a request times out? If so, can this hang be fixed by modifying the NVMe driver instead of by modifying the percpu refcount implementation? Thanks, Bart.