From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754665Ab2A0UmE (ORCPT ); Fri, 27 Jan 2012 15:42:04 -0500 Received: from rcsinet15.oracle.com ([148.87.113.117]:20877 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752859Ab2A0UmB (ORCPT ); Fri, 27 Jan 2012 15:42:01 -0500 Date: Fri, 27 Jan 2012 15:39:28 -0500 From: Konrad Rzeszutek Wilk To: Dan Magenheimer , gregkh@suse.de Cc: linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, Greg Kroah-Hartman , Seth Jennings , Nitin Gupta Subject: Re: [PATCH] zcache: fix deadlock condition Message-ID: <20120127203928.GA17285@phenom.dumpdata.com> References: <356ccc29-31af-4274-b372-c8fd1a9b10cb@default> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <356ccc29-31af-4274-b372-c8fd1a9b10cb@default> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet21.oracle.com [141.146.126.237] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090206.4F230C12.00A5,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 25, 2012 at 02:32:51PM -0800, Dan Magenheimer wrote: > I discovered this deadlock condition awhile ago working on RAMster > but it affects zcache as well. The list spinlock must be > locked prior to the page spinlock and released after. As > a result, the page copy must also be done while the locks are held. > > Applies to 3.2. Konrad, please push (via GregKH?)... > this is definitely a bug fix so need not be pushed during > a -rc0 window. Looks good to me. Greg, could you apply the patch to your tree please? [Or would you rather I sent an GIT pull?] Thanks! > > Signed-off-by: Dan Magenheimer > > diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c > index 56c1f9c..5b9f74e 100644 > --- a/drivers/staging/zcache/zcache-main.c > +++ b/drivers/staging/zcache/zcache-main.c > @@ -358,8 +358,8 @@ static struct zbud_hdr *zbud_create(uint16_t client_id, uint16_t pool_id, > if (unlikely(zbpg == NULL)) > goto out; > /* ok, have a page, now compress the data before taking locks */ > - spin_lock(&zbpg->lock); > spin_lock(&zbud_budlists_spinlock); > + spin_lock(&zbpg->lock); > list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list); > zbud_unbuddied[nchunks].count++; > zh = &zbpg->buddy[0]; > @@ -389,12 +389,11 @@ init_zh: > zh->oid = *oid; > zh->pool_id = pool_id; > zh->client_id = client_id; > - /* can wait to copy the data until the list locks are dropped */ > - spin_unlock(&zbud_budlists_spinlock); > - > to = zbud_data(zh, size); > memcpy(to, cdata, size); > spin_unlock(&zbpg->lock); > + spin_unlock(&zbud_budlists_spinlock); > + > zbud_cumul_chunk_counts[nchunks]++; > atomic_inc(&zcache_zbud_curr_zpages); > zcache_zbud_cumul_zpages++;