FAILED: patch "[PATCH] drm/i915: skip __i915_request_skip() for already signaled" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 4cfe4c0efbdcde742a47813180cc69b132d7598e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026052024-heap-encore-72be@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4cfe4c0efbdcde742a47813180cc69b132d7598e Mon Sep 17 00:00:00 2001
From: Sebastian Brzezinka <[email protected]>
Date: Thu, 16 Apr 2026 13:31:18 +0200
Subject: [PATCH] drm/i915: skip __i915_request_skip() for already signaled
requests

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 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.

index 984d0056c01c..adff482a6c9c 100644
@@ -132,7 +132,8 @@ void __i915_request_reset(struct i915_request *rq, bool guilty)
 	rcu_read_lock(); /* protect the GEM context */
 	if (guilty) {
 		i915_request_set_error_once(rq, -EIO);
-		__i915_request_skip(rq);
+		if (!i915_request_signaled(rq))
+			__i915_request_skip(rq);
 		banned = mark_guilty(rq);
 	} else {
 		i915_request_set_error_once(rq, -EAGAIN);