[Nouveau] Nouveau dmem NULL Pointer deref (SVM)

[Jerome Glisse]

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 ?

Cheers,
Jérôme

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>From 0304725edbaa3b828598a3babb785e6b9555af0b 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: initialize some fields of dmem no matter what
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

On GPU that do not support device memory we left dmem fields uninitialized
and this lead to troube in suspend/resume which try to use those fields. It
seems best to initialize those fields no matter what.

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 | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index aa9fec80492d..35b6e83ead8a 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -593,6 +593,11 @@ nouveau_dmem_init(struct nouveau_drm *drm)
 	unsigned long i, size;
 	int ret;
 
+	mutex_init(&drm->dmem->mutex);
+	INIT_LIST_HEAD(&drm->dmem->chunk_free);
+	INIT_LIST_HEAD(&drm->dmem->chunk_full);
+	INIT_LIST_HEAD(&drm->dmem->chunk_empty);
+
 	/* This only make sense on PASCAL or newer */
 	if (drm->client.device.info.family < NV_DEVICE_INFO_V0_PASCAL)
 		return;
@@ -600,11 +605,6 @@ nouveau_dmem_init(struct nouveau_drm *drm)
 	if (!(drm->dmem = kzalloc(sizeof(*drm->dmem), GFP_KERNEL)))
 		return;
 
-	mutex_init(&drm->dmem->mutex);
-	INIT_LIST_HEAD(&drm->dmem->chunk_free);
-	INIT_LIST_HEAD(&drm->dmem->chunk_full);
-	INIT_LIST_HEAD(&drm->dmem->chunk_empty);
-
 	size = ALIGN(drm->client.device.info.ram_user, DMEM_CHUNK_SIZE);
 
 	/* Initialize migration dma helpers before registering memory */
-- 
2.17.1