[PATCH uprobe, thp v2 4/5] uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT

[Song Liu]

This patches uses newly added FOLL_SPLIT_PMD in uprobe. This enables easy
regroup of huge pmd after the uprobe is disabled (in next patch).

Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
 kernel/events/uprobes.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 3fca7c55d370..88a8e1624bfa 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -153,7 +153,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct page_vma_mapped_walk pvmw = {
-		.page = old_page,
+		.page = compound_head(old_page),
 		.vma = vma,
 		.address = addr,
 	};
@@ -165,8 +165,6 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr,
 				addr + PAGE_SIZE);
 
-	VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page);
-
 	if (!orig) {
 		err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
 					    &memcg, false);
@@ -188,7 +186,9 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 
 	get_page(new_page);
 	if (orig) {
+		lock_page(new_page);  /* for page_add_file_rmap() */
 		page_add_file_rmap(new_page, false);
+		unlock_page(new_page);
 		inc_mm_counter(mm, mm_counter_file(new_page));
 		dec_mm_counter(mm, MM_ANONPAGES);
 	} else {
@@ -482,7 +482,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 retry:
 	/* Read the page with vaddr into memory */
 	ret = get_user_pages_remote(NULL, mm, vaddr, 1,
-			FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL);
+			FOLL_FORCE | FOLL_SPLIT_PMD, &old_page, &vma, NULL);
 	if (ret <= 0)
 		return ret;
 
-- 
2.17.1