From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx174.postini.com [74.125.245.174]) by kanga.kvack.org (Postfix) with SMTP id 907B56B0031 for ; Tue, 6 Aug 2013 05:43:14 -0400 (EDT) Message-ID: <5200C527.5030006@oracle.com> Date: Tue, 06 Aug 2013 17:43:03 +0800 From: Bob Liu MIME-Version: 1.0 Subject: Re: [PATCH] mm: zcache: zcache_cleancache_flush_fs fix References: <1375781762-15344-1-git-send-email-p.sarna@partner.samsung.com> In-Reply-To: <1375781762-15344-1-git-send-email-p.sarna@partner.samsung.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Piotr Sarna Cc: b.zolnierkie@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kyungmin Park Hi Piotr, On 08/06/2013 05:36 PM, Piotr Sarna wrote: > This patch fixes "mm: zcache: core functions added" patch, > available at https://lkml.org/lkml/2013/7/20/90. > It regards incorrect implementation of zcache_cleancache_flush_fs(). > > Function above should be effective only if cleancache pool referred > by pool_id is valid. This issue is checked by testing whether zpool > points to NULL. > > Unfortunately, if filesystem mount fails, such pool is never created > and fs/super.c calls cleancache_invalidate_fs() function with pool_id > parameter set to -1. This results in assigning zpool with pools[-1], > which causes zpool to be not NULL and thus whole function hangs on > uninitialized read-write lock. > > To prevent that behaviour, pool_id should be checked for being positive > before assigning zpool variable with pools[pool_id]. > > Signed-off-by: Piotr Sarna > Acked-by: Bartlomiej Zolnierkiewicz > Signed-off-by: Kyungmin Park Yes, that's a problem. Thank you very much! I'm so glad you are also interesting in zcache. I'm preparing a update version of zcache which is still under testing currently. > --- > mm/zcache.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/zcache.c b/mm/zcache.c > index a2408e8..7e6d2e7 100644 > --- a/mm/zcache.c > +++ b/mm/zcache.c > @@ -600,8 +600,12 @@ static void zcache_cleancache_flush_fs(int pool_id) > struct zcache_rb_entry *entry = NULL; > struct rb_node *node; > unsigned long flags1, flags2; > - struct zcache_pool *zpool = zcache.pools[pool_id]; > + struct zcache_pool *zpool; > + > + if (pool_id < 0) > + return; > > + zpool = zcache.pools[pool_id]; > if (!zpool) > return; > > -- Regards, -Bob -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org