mmu_notifier: add event information to address invalidation v8

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.

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

1 files changed, 12 insertions, 6 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 7ee101eaacdf..eb1b2b53c4a1 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -872,7 +872,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 
 	mmun_start = addr;
 	mmun_end   = addr + PAGE_SIZE;
-	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end,
+					    MMU_KSM_WRITE_PROTECT);
 
 	ptep = page_check_address(page, mm, addr, &ptl, 0);
 	if (!ptep)
@@ -904,7 +905,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 		if (pte_dirty(entry))
 			set_page_dirty(page);
 		entry = pte_mkclean(pte_wrprotect(entry));
-		set_pte_at_notify(mm, addr, ptep, entry);
+		set_pte_at_notify(mm, addr, ptep, entry, MMU_KSM_WRITE_PROTECT);
 	}
 	*orig_pte = *ptep;
 	err = 0;
@@ -912,7 +913,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 out_unlock:
 	pte_unmap_unlock(ptep, ptl);
 out_mn:
-	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end,
+					  MMU_KSM_WRITE_PROTECT);
 out:
 	return err;
 }
@@ -948,7 +950,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 
 	mmun_start = addr;
 	mmun_end   = addr + PAGE_SIZE;
-	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end,
+					    MMU_MIGRATE);
 
 	ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
 	if (!pte_same(*ptep, orig_pte)) {
@@ -961,7 +964,9 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 
 	flush_cache_page(vma, addr, pte_pfn(*ptep));
 	ptep_clear_flush_notify(vma, addr, ptep);
-	set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
+	set_pte_at_notify(mm, addr, ptep,
+			  mk_pte(kpage, vma->vm_page_prot),
+			  MMU_MIGRATE);
 
 	page_remove_rmap(page);
 	if (!page_mapped(page))
@@ -971,7 +976,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 	pte_unmap_unlock(ptep, ptl);
 	err = 0;
 out_mn:
-	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end,
+					  MMU_MIGRATE);
 out:
 	return err;
 }