linux-kernel - Re: DRM Error on Acer Aspire One

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Date:	Tue, 11 May 2010 23:48:27 +0530
From:	Jaswinder Singh Rajput <jaswinderlinux@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Chris Wilson <chris@...is-wilson.co.uk>,
	dri-devel@...ts.freedesktop.org, Dave Airlie <airlied@...ux.ie>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: DRM Error on Acer Aspire One

Hello Andrew,

On Tue, May 11, 2010 at 8:18 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Tue, 11 May 2010 17:10:53 +0100 Chris Wilson <chris@...is-wilson.co.uk> wrote:
>
>> On Tue, 11 May 2010 20:30:07 +0530, Jaswinder Singh Rajput <jaswinderlinux@...il.com> 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.
>

I tested your patch with latest linus git and it works, it fixes the
softirq error.

Now I am only getting DRM errors :

[   42.276059] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer
elapsed... GPU hung
[   42.276398] render error detected, EIR: 0x00000000
[   42.276460] [drm:i915_do_wait_request] *ERROR* i915_do_wait_request
returns -5 (awaiting 18 at 17)

Thanks,
--
Jaswinder Singh.
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