From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756583AbaCRPbj (ORCPT ); Tue, 18 Mar 2014 11:31:39 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.229]:12110 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753543AbaCRPbi (ORCPT ); Tue, 18 Mar 2014 11:31:38 -0400 Date: Tue, 18 Mar 2014 11:31:36 -0400 From: Steven Rostedt To: Steven Rostedt Cc: LKML , Daniel Vetter , Ben Widawsky , Chris Wilson , Ramkumar Ramachandra , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , stable Subject: Re: [PATCH] drm/i915: Do not dereference pointers from ring buffer in evict event Message-ID: <20140318113136.02d2e08b@gandalf.local.home> In-Reply-To: <20140318112737.2192898a@gandalf.local.home> References: <20140318112737.2192898a@gandalf.local.home> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.118:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 18 Mar 2014 11:27:37 -0400 Steven Rostedt wrote: > The TP_printk() should never dereference any pointers, because the ring > buffer can be read at some unknown time in the future. If a device no > longer exists, it can cause a kernel oops. This also makes this > event useless when saving the ring buffer in userspaces tools such as > perf and trace-cmd. > > The i915_gem_evict_vm dereferences the vm pointer which may also not > exist when the ring buffer is read sometime in the future. > > Link: http://lkml.kernel.org/r/1395095198-20034-3-git-send-email-artagnon@gmail.com > Reported-by: Ramkumar Ramachandra Cc: > stable@vger.kernel.org # 3.13+ Bah, claw's mail is playing havoc with my line wraps. Please fix the above when applying, or I can send anothe patch. Thanks :-) I had to re-insert the patch due to it but didn't see the screw up with the Cc of stable. -- Steve > Fixes: bcccff847d1f "drm/i915: trace vm eviction instead of everything" > Signed-off-by: Steven Rostedt > --- > diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h > index 6e580c9..f3e8a90 100644 > --- a/drivers/gpu/drm/i915/i915_trace.h > +++ b/drivers/gpu/drm/i915/i915_trace.h > @@ -238,14 +238,16 @@ TRACE_EVENT(i915_gem_evict_vm, > TP_ARGS(vm), > > TP_STRUCT__entry( > + __field(u32, dev) > __field(struct i915_address_space *, vm) > ), > > TP_fast_assign( > + __entry->dev = dev->primary->index; > __entry->vm = vm; > ), > > - TP_printk("dev=%d, vm=%p", __entry->vm->dev->primary->index, __entry->vm) > + TP_printk("dev=%d, vm=%p", __entry->dev, __entry->vm) > ); > > TRACE_EVENT(i915_gem_ring_sync_to,