From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755120Ab2CMO26 (ORCPT ); Tue, 13 Mar 2012 10:28:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7601 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754481Ab2CMO24 (ORCPT ); Tue, 13 Mar 2012 10:28:56 -0400 Date: Tue, 13 Mar 2012 10:28:20 -0400 From: Vivek Goyal To: Xiaotian Feng Cc: axboe@kernel.dk, tj@kernel.org, linux-kernel@vger.kernel.org, Xiaotian Feng Subject: Re: [PATCH v2] block: fix ioc leak in put_io_context Message-ID: <20120313142820.GF29169@redhat.com> References: <20120312142226.GD17288@redhat.com> <1331659266-21940-1-git-send-email-xtfeng@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1331659266-21940-1-git-send-email-xtfeng@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 13, 2012 at 01:21:06PM -0400, Xiaotian Feng wrote: > When put_io_context is called, if ioc->icq_list is empty and refcount > is 1, kernel will not free the ioc. > > This is caught by following kmemleak: > > unreferenced object 0xffff880036349fe0 (size 216): > comm "sh", pid 2137, jiffies 4294931140 (age 290579.412s) > hex dump (first 32 bytes): > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 01 00 01 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... > backtrace: > [] kmemleak_alloc+0x26/0x50 > [] kmem_cache_alloc_node+0x1cc/0x2a0 > [] create_io_context_slowpath+0x27/0x130 > [] get_task_io_context+0xbb/0xf0 > [] copy_process+0x188e/0x18b0 > [] do_fork+0x11b/0x420 > [] sys_clone+0x28/0x30 > [] stub_clone+0x13/0x20 > [] 0xffffffffffffffff > > ioc should be freed if ioc->icq_list is empty. > Signed-off-by: Xiaotian Feng > --- > block/blk-ioc.c | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/block/blk-ioc.c b/block/blk-ioc.c > index 8b782a6..9690f27 100644 > --- a/block/blk-ioc.c > +++ b/block/blk-ioc.c > @@ -145,6 +145,7 @@ static void ioc_release_fn(struct work_struct *work) > void put_io_context(struct io_context *ioc) > { > unsigned long flags; > + bool free_ioc = false; > > if (ioc == NULL) > return; > @@ -159,8 +160,13 @@ void put_io_context(struct io_context *ioc) > spin_lock_irqsave(&ioc->lock, flags); > if (!hlist_empty(&ioc->icq_list)) > schedule_work(&ioc->release_work); > + else > + free_ioc = true; > spin_unlock_irqrestore(&ioc->lock, flags); > } > + > + if (free_ioc) > + kmem_cache_free(iocontext_cachep, ioc); > } > EXPORT_SYMBOL(put_io_context); This one looks good to me. Tejun? Acked-by: Vivek Goyal Vivek