[PATCH 2/3] mm, mmu_notifier: be explicit about range invalition non-blocking mode

Michal Hocko
2018-08-27T11:26:42Z

From: Michal Hocko <mhocko@suse.com>

If invalidate_range_start is called for !blocking mode then all
callbacks have to guarantee they will no block/sleep. The same obviously
applies to invalidate_range_end because this operation pairs with the
former and they are called from the same context. Make sure this is
appropriately documented.

Cc: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
include/linux/mmu_notifier.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 133ba78820ee..698e371aafe3 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -153,7 +153,9 @@ struct mmu_notifier_ops {
*
* If blockable argument is set to false then the callback cannot
* sleep and has to return with -EAGAIN. 0 should be returned
- * otherwise.
+ * otherwise. Please note that if invalidate_range_start approves
+ * a non-blocking behavior then the same applies to
+ * invalidate_range_end.
*
*/
int (*invalidate_range_start)(struct mmu_notifier *mn,
--
2.18.0