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Commit 11377c3e authored by Thomas Hellstrom's avatar Thomas Hellstrom Committed by Greg Kroah-Hartman
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drm/ttm: Restore ttm prefaulting 



commit 941f2f72dbbe0cf8c2d6e0b180a8021a0ec477fa upstream.

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: default avatarThomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/330387/


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 33af2a8e

drivers/gpu/drm/ttm/ttm_bo_vm.c

+7 −9
Original line number Diff line number Diff line
@@ -273,15 +273,13 @@ 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))