Subject: FAILED: patch "[PATCH] drm/amdgpu: Fix last_update fence leak in amdgpu_vm_init()" failed to apply to 5.15-stable tree
To: vulab@iscas.ac.cn,alexander.deucher@amd.com
Cc: <stable@vger.kernel.org>
From: <gregkh@linuxfoundation.org>
Date: Tue, 29 Sep 2026 10:23:16 +0200
Message-ID: <2026092916-yearling-rise-4267@gregkh>
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The patch below does not apply to the 5.15-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 <stable@vger.kernel.org>.

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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x b4f7b4459b1b155e4c4977a6482b5df2cf08758c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092916-yearling-rise-4267@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:


thanks,

greg k-h

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

From b4f7b4459b1b155e4c4977a6482b5df2cf08758c Mon Sep 17 00:00:00 2001
From: Wentao Liang <vulab@iscas.ac.cn>
Date: Wed, 16 Sep 2026 09:55:36 +0000
Subject: [PATCH] drm/amdgpu: Fix last_update fence leak in amdgpu_vm_init()

amdgpu_vm_init() initializes vm->last_update, vm->last_unlocked and
vm->last_tlb_flush with references to the stub fence taken via
dma_fence_get_stub().  The error label at the end of the function
releases the last_unlocked and last_tlb_flush references with
dma_fence_put(), but the reference stored in vm->last_update is never
dropped, so whenever the page table root creation, the reservation of
the root BO or the PASID registration fails, the stub fence reference
leaks.

Drop the vm->last_update reference together with the other stub fence
references on the error path.

Fixes: 187916e6ed9d ("drm/amdgpu: install stub fence into potential unused fence pointers")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e7979c84fc05a176bdf855ee664871b1648404c9)
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index bb04101b0fb5..4a63b472f68e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2678,6 +2678,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	amdgpu_bo_unref(&root_bo);
 
 error_free_delayed:
+	dma_fence_put(vm->last_update);
 	dma_fence_put(vm->last_tlb_flush);
 	dma_fence_put(vm->last_unlocked);
 	ttm_lru_bulk_move_fini(&adev->mman.bdev, &vm->lru_bulk_move);