From 941f2f72dbbe0cf8c2d6e0b180a8021a0ec477fa Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom@vmware.com>
Date: Thu, 12 Sep 2019 20:38:54 +0200
Subject: drm/ttm: Restore ttm prefaulting
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Git-commit: 941f2f72dbbe0cf8c2d6e0b180a8021a0ec477fa
Patch-mainline: v5.4-rc4
References: bsc#1152489
Commit 4daa4fba3a38 ("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: 4daa4fba3a38 ("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/
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 76eedb963693..46dc3de7e81b 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -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))
- goto out_io_unlock;
+ /* 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))
--
2.28.0