FAILED: patch "[PATCH] drm/amdkfd: Don't acquire buffers during CRIU queue restore." failed to apply to 6.18-stable tree

The patch below does not apply to the 6.18-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-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 8a93f77aec65574b8152c88eb73613336f92f86b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026091650-tackling-tumbling-d114@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 8a93f77aec65574b8152c88eb73613336f92f86b Mon Sep 17 00:00:00 2001
From: David Francis <[email protected]>
Date: Tue, 30 Jun 2026 09:58:18 -0400
Subject: [PATCH] drm/amdkfd: Don't acquire buffers during CRIU queue restore.

kfd_criu_restore_queue's call of kfd_queue_acquire_buffers was failing for multiple reasons
- The ctl_stack_size set by the CRIU plugin doesn't match what is expected by acquire_buffers
- The svm buffer cannot be acquired at this point because CRIU may not have restored it, or may have restored it to a different address.

The only reason acquire_buffers was necessary here was to avoid a null ptr dereference in init_user_queue.

Just put in a check for that dereference; it doesn't appear to come up in real use cases right now. That is, there is no usage of CRIU with shared MES.

This is a partial revert of
commit 20a5e7ffdfec ("drm/amdkfd: Properly acquire queue buffers in CRIU restore")

index 0ac35789b239..b8c36907d536 100644
@@ -265,6 +265,11 @@ static int init_user_queue(struct process_queue_manager *pqm,
 	(*q)->process = pqm->process;
 
 	if (dev->kfd->shared_resources.enable_mes) {
+		if (!q_properties->wptr_bo) {
+			pr_debug("Queue initialization with shared MES requires queue buffers to be initialized\n");
+			return -EINVAL;
+		}
+
 		retval = amdgpu_amdkfd_alloc_kernel_mem(dev->adev,
 						AMDGPU_MES_GANG_CTX_SIZE,
 						AMDGPU_GEM_DOMAIN_GTT,

@@ -1042,18 +1047,10 @@ int kfd_criu_restore_queue(struct kfd_process *p,
 	memset(&qp, 0, sizeof(qp));
 	set_queue_properties_from_criu(&qp, q_data, NUM_XCC(pdd->dev->adev->gfx.xcc_mask));
 
-	ret = kfd_queue_acquire_buffers(pdd, &qp);
-	if (ret) {
-		pr_debug("failed to acquire user queue buffers for CRIU\n");
-		goto exit;
-	}
-
 	print_queue_properties(&qp);
 
 	ret = pqm_create_queue(&p->pqm, pdd->dev, &qp, &queue_id, q_data, mqd, ctl_stack, NULL);
 	if (ret) {
-		kfd_queue_unref_bo_vas(pdd, &qp);
-		kfd_queue_release_buffers(pdd, &qp);
 		pr_err("Failed to create new queue err:%d\n", ret);
 		goto exit;
 	}