mmu_notifier: add event information to address invalidation v9

The event information will be useful for new user of mmu_notifier API.
The event argument differentiate between a vma disappearing, a page
being write protected or simply a page being unmaped. This allow new
user to take different path for different event for instance on unmap
the resource used to track a vma are still valid and should stay around.
While if the event is saying that a vma is being destroy it means that any
resources used to track this vma can be free.

Changed since v1:
  - renamed action into event (updated commit message too).
  - simplified the event names and clarified their usage
    also documenting what exceptation the listener can have in
    respect to each event.

Changed since v2:
  - Avoid crazy name.
  - Do not move code that do not need to move.

Changed since v3:
  - Separate huge page split from mlock/munlock and softdirty.

Changed since v4:
  - Rebase (no other changes).

Changed since v5:
  - Typo fix.
  - Changed zap_page_range from MMU_MUNMAP to MMU_MIGRATE to reflect the
    fact that the address range is still valid just the page backing it
    are no longer.

Changed since v6:
  - try_to_unmap_one() only invalidate when doing migration.
  - Differentiate fork from other case.

Changed since v7:
  - Renamed MMU_HUGE_PAGE_SPLIT to MMU_HUGE_PAGE_SPLIT.
  - Renamed MMU_ISDIRTY to MMU_CLEAR_SOFT_DIRTY.
  - Renamed MMU_WRITE_PROTECT to MMU_KSM_WRITE_PROTECT.
  - English syntax fixes.

Changed since v8:
  - Added freeze/unfreeze for new huge page splitting.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 229cb546bee0..3101b70dd273 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1051,11 +1051,13 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 				downgrade_write(&mm->mmap_sem);
 				break;
 			}
-			mmu_notifier_invalidate_range_start(mm, 0, -1);
+			mmu_notifier_invalidate_range_start(mm, 0, -1,
+							MMU_CLEAR_SOFT_DIRTY);
 		}
 		walk_page_range(0, ~0UL, &clear_refs_walk);
 		if (type == CLEAR_REFS_SOFT_DIRTY)
-			mmu_notifier_invalidate_range_end(mm, 0, -1);
+			mmu_notifier_invalidate_range_end(mm, 0, -1,
+							MMU_CLEAR_SOFT_DIRTY);
 		flush_tlb_mm(mm);
 		up_read(&mm->mmap_sem);
 out_mm: