From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f193.google.com ([209.85.220.193]:33983 "EHLO mail-qk0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750893AbdA1NVv (ORCPT ); Sat, 28 Jan 2017 08:21:51 -0500 Date: Sat, 28 Jan 2017 07:52:51 -0500 From: Tejun Heo To: Douglas Miller Cc: linux-kernel@vger.kernel.org, Christoph Lameter , linux-block@vger.kernel.org, stable@vger.kernel.org, Guilherme Piccoli Subject: Re: [PATCH V3 1/1] percpu-refcount: fix reference leak during percpu-atomic transition Message-ID: <20170128125251.GA5797@mtj.duckdns.org> References: <1485607340-13728-1-git-send-email-dougmill@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1485607340-13728-1-git-send-email-dougmill@linux.vnet.ibm.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Sat, Jan 28, 2017 at 06:42:20AM -0600, Douglas Miller wrote: > percpu_ref_tryget() and percpu_ref_tryget_live() should return > "true" IFF they acquire a reference. But the return value from > atomic_long_inc_not_zero() is a long and may have high bits set, > e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines > is bool so the reference may actually be acquired but the routines > return "false" which results in a reference leak since the caller > assumes it does not need to do a corresponding percpu_ref_put(). Applied to percpu/for-4.10-fixes w/ stable cc'd. Thanks! -- tejun