From 4cfe4c0efbdcde742a47813180cc69b132d7598e Mon Sep 17 00:00:00 2001 From: Sebastian Brzezinka 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. Fixes: 36e191f0644b ("drm/i915: Apply i915_request_skip() on submission") Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/13729 Signed-off-by: Sebastian Brzezinka Cc: stable@vger.kernel.org # v5.7+ Reviewed-by: Krzysztof Karas Reviewed-by: Andi Shyti Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/fe76921d35b6ae85aa651822726d0d9815aa5362.1776339012.git.sebastian.brzezinka@intel.com (cherry picked from commit 5ba54393dcd7adf75a9f39f5a933b1538349cad5) Signed-off-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/gt/intel_reset.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c index 984d0056c01c..adff482a6c9c 100644 --- a/drivers/gpu/drm/i915/gt/intel_reset.c +++ b/drivers/gpu/drm/i915/gt/intel_reset.c @@ -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);