Re: [PATCH] drm/i915: skip __i915_request_skip() for already signaled requests

[Andi Shyti <andi.shyti@linux.intel.com>]

Hi Sebastian,

On Mon, Apr 20, 2026 at 09:18:03AM +0000, Krzysztof Karas wrote:
> On 2026-04-16 at 13:31:18 +0200, Sebastian Brzezinka wrote:
> > After a GPU reset the HWSP is zeroed, so previously completed
> > requests appear incomplete. If such a request is picked up during
> > reset_rewind() and marked guilty, i915_request_set_error_once()
> > returns early (fence already signaled), leaving fence.error without
> > a fatal error code. The subsequent __i915_request_skip() then hits:
> > ```
> > GEM_BUG_ON(!fatal_error(rq->fence.error))
> > ```
> > 
> > Fixes a kernel BUG observed on Sandy Bridge (Gen6) during
> By "Fixes" do you mean this patch? Or are you referring to the
> tag "Fixes:" below? If former would be the case, then imperative
> form might be better: Fix.

Pour parler: the imperative is used in the last paragraph:
"Guard" :-)

> 
> In any case the patch looks sane:
> Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
> 
> > heartbeat-triggered engine resets.
> > ```
> > kernel BUG at drivers/gpu/drm/i915/i915_request.c:556!
> > RIP: __i915_request_skip+0x15e/0x1d0 [i915]
> > ...
> > __i915_request_reset+0x212/0xa70 [i915]
> > reset_rewind+0xe4/0x280 [i915]
> > intel_gt_reset+0x30d/0x5b0 [i915]
> > heartbeat+0x516/0x530 [i915]
> > ```
> > 
> > Guard __i915_request_skip() with i915_request_signaled(), if the
> > fence is already signaled, the ring content is committed and there
> > is nothing left to skip.
> > 
> > Cc: stable@vger.kernel.org
> > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/13729
> > Fixes: 36e191f0644b ("drm/i915: Apply i915_request_skip() on submission")
> > Signed-off-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>

Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>

Thanks,
Andi