From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from proofpoint-cluster.metrocast.net ([65.175.128.136]:35358 "EHLO proofpoint-cluster.metrocast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754408Ab1CKAeZ (ORCPT ); Thu, 10 Mar 2011 19:34:25 -0500 Subject: Re: BUG at mm/mmap.c:2309 when cx18.ko and cx18-alsa.ko loaded From: Andy Walls To: Hugh Dickins Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, David Miller , linux-media@vger.kernel.org, Devin Heitmueller In-Reply-To: <1299445446.2310.157.camel@localhost> References: <1299204400.2812.35.camel@localhost> <1299362366.2570.27.camel@localhost> <1299377017.2341.50.camel@localhost> <1299445446.2310.157.camel@localhost> Content-Type: text/plain; charset="UTF-8" Date: Thu, 10 Mar 2011 19:34:38 -0500 Message-ID: <1299803678.13462.14.camel@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit List-ID: Sender: On Sun, 2011-03-06 at 16:04 -0500, Andy Walls wrote: > On Sun, 2011-03-06 at 10:37 -0800, Hugh Dickins wrote: > > I do expect the underlying problem to be somewhere down the driver > > end, given that nobody else has been reporting these issues. I'm > > hoping that once the cx18 guys have time to try to reproduce it, > > they'll be better able to track it down. Hi Hugh, You were correct. The mistake was in the cx18 driver, in the last thing that I touched, of course. The code causing the bug isn't anywhere aside from my private repo. All, Sorry for all the noise. The bug was so idiotic, I fell compelled to show the fix: diff --git a/drivers/media/video/cx18/cx18-scb.c b/drivers/media/video/cx18/cx18 index fd89ad0..d17ffc8 100644 --- a/drivers/media/video/cx18/cx18-scb.c +++ b/drivers/media/video/cx18/cx18-scb.c @@ -28,8 +28,8 @@ int cx18_scb_init_mdl_ent_mgmt(struct cx18 *cx) { - cx->scb_mdl_ent_map = kzalloc(BITS_TO_LONGS(SCB_MDL_ENTRIES), - GFP_KERNEL); + cx->scb_mdl_ent_map = kzalloc(BITS_TO_LONGS(SCB_MDL_ENTRIES) + * sizeof(long), GFP_KERNEL); if (cx->scb_mdl_ent_map == NULL) { CX18_ERR("Fatal: unable to allocate bitmap for managing SCB MDL" "entries\n"); So now the subsequent call to bitmap_zero(cx->scb_mdl_ent_map, SCB_MDL_ENTRIES); doesn't walk off the end of what was allocated. Apparently BITS_TO_LONGS() is not BITS_TO_LONGS_TO_BYTES(). Regards, Andy