On Sun, Jun 05, 2016 at 01:55:00PM +0200, Stefan Wahren wrote:
Hi Eric,
[add Daniel]
Eric Anholt eric@anholt.net hat am 4. Juni 2016 um 22:32 geschrieben:
Stefan Wahren stefan.wahren@i2se.com writes:
Hi,
i tried to boot 4.7.0-rc1-next-20160602 with bcm2835_defconfig on a Raspberry Pi B.
Unfortunately it crashes with a NULL pointer dereference and many oops following: ... [ 2.209373] vc4-drm soc:gpu: bound 20902000.hdmi (ops vc4_hdmi_ops) [ 2.228303] vc4-drm soc:gpu: bound 20206000.pixelvalve (ops vc4_crtc_ops) [ 2.247681] vc4-drm soc:gpu: bound 20207000.pixelvalve (ops vc4_crtc_ops) [ 2.270300] vc4-drm soc:gpu: bound 20807000.pixelvalve (ops vc4_crtc_ops) [ 2.288902] vc4-drm soc:gpu: bound 20400000.hvs (ops vc4_hvs_ops) [ 2.307006] vc4-drm soc:gpu: bound 20c00000.v3d (ops vc4_v3d_ops) [ 2.325069] fb: switching to vc4drmfb from simple [ 2.341322] Console: switching to colour dummy device 80x30 [ 2.350955] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [ 2.357821] [drm] No driver support for vblank timestamp query. [ 2.368495] mmc0: new SDHC card at address 1234 [ 2.374284] mmcblk0: mmc0:1234 SA32G 29.3 GiB [ 2.381213] mmcblk0: p1 p2 [ 2.398018] vc4-drm soc:gpu: failed to allocate buffer with size 9216000 [ 2.404912] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 2.413070] pgd = c0004000 [ 2.415856] [00000000] *pgd=00000000 [ 2.419501] Internal error: Oops: 80000005 [#1] ARM [ 2.424425] CPU: 0 PID: 6 Comm: kworker/u2:0 Not tainted 4.7.0-rc1-next-20160602+ #2 [ 2.432214] Hardware name: BCM2835 [ 2.435677] Workqueue: deferwq deferred_probe_work_func [ 2.440948] task: cb8957c0 ti: cb8b2000 task.ti: cb8b2000 [ 2.446378] PC is at 0x0 [ 2.448953] LR is at drm_gem_cma_create+0xf0/0x108
Figure out where in drm_gem_cma_create() you are?
It was the first call in the error path. I attached a patch which fixed the NULL pointer dereference for me. But i think it's not a proper one and seems to be related to 50cbc132460d ("drm: Use the driver's gem_object_free function from CMA helpers.")
-next kernels have been working for me on Pi 2s and 3s, and jumping to a NULL seems surprising for that function.
Sure they have enough memory but my Pi 1 has only 256 RAM. I didn't expect VC4 to work, but not a crash ;-)
Stefan
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index e1ab008..91c19cc 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -121,7 +121,9 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, return cma_obj;
error:
- drm->driver->gem_free_object(&cma_obj->base);
- if (drm->driver->gem_free_object)
drm->driver->gem_free_object(&cma_obj->base);- return ERR_PTR(ret);
} EXPORT_SYMBOL_GPL(drm_gem_cma_create);
Patch for this (and a few others just like it) landed in -rc2. -Daniel