drm/i915: make i915_gem_mmap_ioctl wait for mmap_sem killable

i915_gem_mmap_ioctl relies on mmap_sem for write.  If the waiting task
gets killed by the oom killer it would block oom_reaper from
asynchronous address space reclaim and reduce the chances of timely OOM
resolving.  Wait for the lock in the killable mode and return with EINTR
if the task got killed while waiting.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 233adc31ef0c9ed32b0cc63cefb78b23cc0d82c6..ddd1d78c346f39ee4e6953de40ea97267634105c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1754,7 +1754,10 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                struct mm_struct *mm = current->mm;
                struct vm_area_struct *vma;
 
-               down_write(&mm->mmap_sem);
+               if (down_write_killable(&mm->mmap_sem)) {
+                       drm_gem_object_unreference_unlocked(obj);
+                       return -EINTR;
+               }
                vma = find_vma(mm, addr);
                if (vma)
                        vma->vm_page_prot =