Make sure the underlying VMA in the process address space is the
same as it was during vm_mmap to avoid applying WC to wrong VMA.
A more long-term solution would be to have vm_mmap_locked variant
in linux/mmap.h for when caller wants to hold mmap_sem for an
extended duration.
Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user mappings for objects")
Reported-by: Adam Zabrocki <adamza@xxxxxxxxxxxxx>
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.0+
Cc: Akash Goel <akash.goel@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Adam Zabrocki <adamza@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 062c8395557c..f1d594a53978 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1680,6 +1680,15 @@ i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
return 0;
}
+static inline bool
+match_gem_vma(struct vm_area_struct *vma, struct file *filp,
+ unsigned long addr, unsigned long size)
+{
+ return vma && vma->vm_file == filp &&
+ vma->vm_start == addr &&
+ (vma->vm_end - vma->vm_start) == size;
+}
+
/**
* i915_gem_mmap_ioctl - Maps the contents of an object, returning the address
* it is mapped to.
@@ -1738,7 +1747,7 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
return -EINTR;
}
vma = find_vma(mm, addr);
- if (vma)
+ if (match_gem_vma(vma, obj->base.filp, addr, args->size))
vma->vm_page_prot =
pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
else
--
2.17.2
