drivers/gpu/drm/i915/i915_irq.c:i915_error_object_create(): use correct kmap-atomic slot

i915_error_object_create() is called from the timer interrupt and hence
can corrupt the KM_USER0 slot.  Use KM_IRQ0 instead.
Reported-by: NJaswinder Singh Rajput <jaswinderlinux@gmail.com>
Tested-by: NJaswinder Singh Rajput <jaswinderlinux@gmail.com>
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/i915_irq.c

@@ -456,11 +456,15 @@ i915_error_object_create(struct drm_device *dev,
 
 	for (page = 0; page < page_count; page++) {
 		void *s, *d = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+		unsigned long flags;
+
 		if (d == NULL)
 			goto unwind;
-		s = kmap_atomic(src_priv->pages[page], KM_USER0);
+		local_irq_save(flags);
+		s = kmap_atomic(src_priv->pages[page], KM_IRQ0);
 		memcpy(d, s, PAGE_SIZE);
-		kunmap_atomic(s, KM_USER0);
+		kunmap_atomic(s, KM_IRQ0);
+		local_irq_restore(flags);
 		dst->pages[page] = d;
 	}
 	dst->page_count = page_count;