From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932792Ab2BJWnc (ORCPT ); Fri, 10 Feb 2012 17:43:32 -0500 Received: from mail-pw0-f46.google.com ([209.85.160.46]:59900 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932731Ab2BJWn1 (ORCPT ); Fri, 10 Feb 2012 17:43:27 -0500 MIME-Version: 1.0 Message-Id: <20120210222952.450793714@clark.kroah.org> User-Agent: quilt/0.51-15.1 Date: Fri, 10 Feb 2012 14:30:42 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Dan Magenheimer , Konrad Rzeszutek Wilk Subject: [patch 83/86] zcache: fix deadlock condition In-Reply-To: <20120210223514.GA24190@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Magenheimer commit 9256a4789be3dae37d00924c03546ba7958ea5a3 upstream. 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. Signed-off-by: Dan Magenheimer Acked-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zcache/zcache-main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/drivers/staging/zcache/zcache-main.c +++ b/drivers/staging/zcache/zcache-main.c @@ -358,8 +358,8 @@ static struct zbud_hdr *zbud_create(uint 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++;