On Fri, Aug 23, 2013 at 11:20:42PM +0300, Pasi Kärkkäinen wrote:
On Thu, Aug 22, 2013 at 09:12:40AM +0200, Maarten Lankhorst wrote:
Op 22-08-13 02:10, Ilia Mirkin schreef:
The code expects non-VRAM mem nodes to have a pages list. If that's not set, it will do a null deref down the line. Warn on that condition and return an error.
See https://bugs.freedesktop.org/show_bug.cgi?id=64774
Reported-by: Pasi Kärkkäinen pasik@iki.fi Tested-by: Pasi Kärkkäinen pasik@iki.fi Signed-off-by: Ilia Mirkin imirkin@alum.mit.edu Cc: stable@vger.kernel.org # 3.8+
I don't exactly understand what's going on, but this is just a straightforward way to avoid a null deref that you see happens in the bug. I haven't figured out the root cause of this, but it's getting well into the "I have no idea how TTM works" space. However this seems like a bit of defensive programming -- nouveau_vm_map_sg will pass node->pages as a list down, which will be dereferenced by nvc0_vm_map_sg. Perhaps the other arguments should make that dereferencing not happen, but it definitely was happening here, as you can see in the bug.
Ben/Maarten, I'll let you judge whether this check is appropriate, since like I hope I was able to convey above, I'm just not really sure :)
Not it really isn't appropriate..
You'd have to call call nouveau_vm_map_sg_table instead, the only place that doesn't handle that correctly is where it's not expected to be called.
Here, have a completely untested patch to fix things...
Maarten: I've been testing this stuff with Linux 3.10.x, so I had to modify the patch a bit to make it apply there.. I've attached the modified copy that applies to 3.10.9, hopefully I did the backport correctly.
With Linux 3.10.9 and the patch applied the kernel doesn't crash anymore, and I get this error in dmesg:
[ 76.105643] nouveau W[ DRM] Trying to create a fb in vram with valid_domains=00000004
Does that help?
Any comments?
Maarten's patch works for me, I get that warning instead of a kernel crash, but it's also a bigger change that doesn't apply to older kernels as-is.
Ilia's original patch in this thread can be applied to older kernels as-is, and it also prevents the kernel crash from happening.
Should we get both applied, so Ilia's patch can be CC'd to stable ?
-- Pasi
--- linux-3.10.9-100.fc18.x86_64/drivers/gpu/drm/nouveau/nouveau_display.c.orig 2013-07-01 01:13:29.000000000 +0300 +++ linux-3.10.9-100.fc18.x86_64/drivers/gpu/drm/nouveau/nouveau_display.c 2013-08-23 19:56:52.038234281 +0300 @@ -137,18 +137,31 @@ { struct nouveau_framebuffer *nouveau_fb; struct drm_gem_object *gem;
struct nouveau_bo *nvbo; int ret;
gem = drm_gem_object_lookup(dev, file_priv, mode_cmd->handles[0]); if (!gem) return ERR_PTR(-ENOENT);
nvbo = nouveau_gem_object(gem);
if (!(nvbo->valid_domains & NOUVEAU_GEM_DOMAIN_VRAM)) {
nv_warn(nouveau_drm(dev), "Trying to create a fb in vram with"" valid_domains=%08x\n", nvbo->valid_domains);ret = -EINVAL;drm_gem_object_unreference(gem);return ERR_PTR(ret);}
nouveau_fb = kzalloc(sizeof(struct nouveau_framebuffer), GFP_KERNEL);
- if (!nouveau_fb)
- if (!nouveau_fb) {
drm_gem_object_unreference(gem);- }
- ret = nouveau_framebuffer_init(dev, nouveau_fb, mode_cmd, nouveau_gem_object(gem));
- ret = nouveau_framebuffer_init(dev, nouveau_fb, mode_cmd, nvbo); if (ret) {
kfree(nouveau_fb);
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