[PATCH 1/3] mm: Check if mmu notifier callbacks are allowed to fail

[Daniel Vetter]

Just a bit of paranoia, since if we start pushing this deep into
callchains it's hard to spot all places where an mmu notifier
implementation might fail when it's not allowed to.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: "Christian König" <christian.koenig at amd.com>
Cc: David Rientjes <rientjes at google.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: "Jérôme Glisse" <jglisse at redhat.com>
Cc: linux-mm at kvack.org
Cc: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 mm/mmu_notifier.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 5119ff846769..59e102589a25 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -190,6 +190,8 @@ int __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
 				pr_info("%pS callback failed with %d in %sblockable context.\n",
 						mn->ops->invalidate_range_start, _ret,
 						!blockable ? "non-" : "");
+				WARN(blockable,"%pS callback failure not allowed\n",
+				     mn->ops->invalidate_range_start);
 				ret = _ret;
 			}
 		}
-- 
2.19.1