[Nouveau] Nouveau dmem NULL Pointer deref (SVM)

[Jerome Glisse]

On Thu, Mar 21, 2019 at 01:12:07PM -0400, Jerome Glisse wrote:
> On Thu, Mar 21, 2019 at 04:59:14PM +0100, Tobias Klausmann wrote:
> > Hi,
> > 
> > just for your information and maybe for some help: with 5.1rc1 and SVM
> > enabled i see the following backtrace [1] when the nouveau card (reverse
> > prime) goes to sleep, for now i have papered over with [2] which leaves me
> > with userspace hangs. Any pointers where to look for the actual culprit?
> > 
> > PS: Card is: nouveau 0000:01:00.0: NVIDIA GP106 (136000a1)
> > 
> > Greetings,
> > 
> > Tobias
> 
> Can you check if attached patch fix the issue ?

Sorry sent bogus patch here is a good one ...

Cheers,
Jérôme


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>From 5b413953ba7abd3f92f46ef8261cd64368f0ae84 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= <jglisse at redhat.com>
Date: Thu, 21 Mar 2019 13:08:46 -0400
Subject: [PATCH] gpu/nouveau: empty chunk do not have a buffer object
 associated with them.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Empty chunk do not have a bo associated with them so no need to pin/unpin
on suspend/resume.

Signed-off-by: Jérôme Glisse <jglisse at redhat.com>
Cc: Ben Skeggs <bskeggs at redhat.com>
Cc: dri-devel at lists.freedesktop.org
Cc: nouveau at lists.freedesktop.org
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: dri-devel at lists.freedesktop.org
---
 drivers/gpu/drm/nouveau/nouveau_dmem.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index aa9fec80492d..a510dbe9a9cb 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -456,11 +456,6 @@ nouveau_dmem_resume(struct nouveau_drm *drm)
 		/* FIXME handle pin failure */
 		WARN_ON(ret);
 	}
-	list_for_each_entry (chunk, &drm->dmem->chunk_empty, list) {
-		ret = nouveau_bo_pin(chunk->bo, TTM_PL_FLAG_VRAM, false);
-		/* FIXME handle pin failure */
-		WARN_ON(ret);
-	}
 	mutex_unlock(&drm->dmem->mutex);
 }
 
@@ -479,9 +474,6 @@ nouveau_dmem_suspend(struct nouveau_drm *drm)
 	list_for_each_entry (chunk, &drm->dmem->chunk_full, list) {
 		nouveau_bo_unpin(chunk->bo);
 	}
-	list_for_each_entry (chunk, &drm->dmem->chunk_empty, list) {
-		nouveau_bo_unpin(chunk->bo);
-	}
 	mutex_unlock(&drm->dmem->mutex);
 }
 
-- 
2.17.1