On Tue, 11 May 2010 17:10:53 +0100 Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 11 May 2010 20:30:07 +0530, Jaswinder Singh Rajput <jaswinderlinux@xxxxxxxxx> wrote:
> > Hello,
> >
> > With latest git kernel, I am getting following DRM error and not
> > getting XWindows :
>
> [snip]
>
> Hmm, there are still patches for capturing error state that haven't gone
> upstream, shame on me.
>
> That error is a secondary issue to the GPU hang that is being reported. If
> it is a regression caused by a kernel update it would be very useful if
> you could bisect to the erroneous commit.
It helps if one reads the code and the trace...
i915_error_object_create() is using KM_USER0 from softirq context.
That's a bug, and a pretty serious one. If some innocent civilian is
writing highmem data to disk and this timer interrupt fires and trashes
his KM_USER0 slot, the disk contents will be corrupted.
Something like this...
--- a/drivers/gpu/drm/i915/i915_irq.c~a
+++ a/drivers/gpu/drm/i915/i915_irq.c
@@ -456,11 +456,15 @@ i915_error_object_create(struct drm_devi
for (page = 0; page < page_count; page++) {
void *s, *d = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+ unsigned long flags;
+
if (d == NULL)
goto unwind;
- s = kmap_atomic(src_priv->pages[page], KM_USER0);
+ local_irq_save(flags);
+ s = kmap_atomic(src_priv->pages[page], KM_IRQ0);
memcpy(d, s, PAGE_SIZE);
- kunmap_atomic(s, KM_USER0);
+ kunmap_atomic(s, KM_IRQ0);
+ local_irq_restore(flags);
dst->pages[page] = d;
}
dst->page_count = page_count;
_
Please let's get a tested fix for this into 2.6.34.
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
