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drm/i915: Don't prefault the entire obj if the vma is smaller

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Take the minimum of the object size and the vma size and prefault
only that much. Avoids a SIGBUS when mmapping only a portion of the
object.

Prefaulting was introduced here:
 commit b90b91d870
 Author: Chris Wilson <chris@chris-wilson.co.uk>
 Date:   Tue Jun 10 12:14:40 2014 +0100

    drm/i915: Prefault the entire object on first page fault

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Testcase: igt/gem_mmap/short-mmap
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2014-06-17 21:03:00 +03:00 committed by Daniel Vetter
parent 84c33a64b4
commit beff0d0f61
1 changed files with 4 additions and 1 deletions
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5
drivers/gpu/drm/i915/i915_gem.c
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@ -1570,9 +1570,12 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
pfn >>= PAGE_SHIFT;
if (!obj->fault_mappable) {
unsigned long size = min_t(unsigned long,
vma->vm_end - vma->vm_start,
obj->base.size);
int i;
for (i = 0; i < obj->base.size >> PAGE_SHIFT; i++) {
for (i = 0; i < size >> PAGE_SHIFT; i++) {
ret = vm_insert_pfn(vma,
(unsigned long)vma->vm_start + i * PAGE_SIZE,
pfn + i);