Commit 941f2f72 authored Sep 12, 2019 by Thomas Hellstrom Committed by Christian König Oct 14, 2019

drm/ttm: Restore ttm prefaulting



Commit 4daa4fba ("gpu: drm: ttm: Adding new return type vm_fault_t")
broke TTM prefaulting. Since vmf_insert_mixed() typically always returns
VM_FAULT_NOPAGE, prefaulting stops after the second PTE.

Restore (almost) the original behaviour. Unfortunately we can no longer
with the new vm_fault_t return type determine whether a prefaulting
PTE insertion hit an already populated PTE, and terminate the insertion
loop. Instead we continue with the pre-determined number of prefaults.

Fixes: 4daa4fba ("gpu: drm: ttm: Adding new return type vm_fault_t")
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/330387/

parent 73a88e4c

drivers/gpu/drm/ttm/ttm_bo_vm.c

+7 −9

Original line number	Diff line number	Diff line
		@@ -278,15 +278,13 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
		else
		ret = vmf_insert_pfn(&cvma, address, pfn);

		/*
		* Somebody beat us to this PTE or prefaulting to
		* an already populated PTE, or prefaulting error.
		*/

		if (unlikely((ret == VM_FAULT_NOPAGE && i > 0)))
		break;
		else if (unlikely(ret & VM_FAULT_ERROR))
		/* Never error on prefaulted PTEs */
		if (unlikely((ret & VM_FAULT_ERROR))) {
		if (i == 0)
		goto out_io_unlock;
		else
		break;
		}

		address += PAGE_SIZE;
		if (unlikely(++page_offset >= page_last))

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