Re: [PATCH] drm/i915: Call page_address() on page acquired with GFP_KERNEL flag

[Tvrtko Ursulin]

On 14/06/2023 13:35, Sumitra Sharma wrote:
Pages allocated with GFP_KERNEL cannot come from Highmem.
That is why there is no need to call kmap() on them.

Are you sure it is GFP_KERNEL backed and not tmpfs? I am not sure myself 
so let me copy Matt and Thomas if they happen to know off hand.

Regards,

Tvrtko

Therefore, don't call kmap() on the page coming from
vma_res->bi.pages using for_each_sgt_page() in
i915_vma_coredump_create().

Use a plain page_address() to get the kernel address instead.

Signed-off-by: Sumitra Sharma <sumitraar...@gmail.com>
---
  drivers/gpu/drm/i915/i915_gpu_error.c | 3 +--
  1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c 
b/drivers/gpu/drm/i915/i915_gpu_error.c
index f020c0086fbc..6f51cb4fc55c 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1164,9 +1164,8 @@ i915_vma_coredump_create(const struct intel_gt *gt,
  
  			drm_clflush_pages(&page, 1);
  
-			s = kmap(page);
+                       s = page_address(page);
                        ret = compress_page(compress, s, dst, false);
-                       kunmap(page);
  
  			drm_clflush_pages(&page, 1);