[PATCH 09/12] mm, uprobes: convert __replace_page() to page_check_walk()

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

For consistency, it worth converting all page_check_address() to
page_check_walk(), so we could drop the former.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 kernel/events/uprobes.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 1e65c79e52a6..6dbaa93b22fa 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -153,14 +153,19 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 				struct page *old_page, struct page *new_page)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	spinlock_t *ptl;
-	pte_t *ptep;
+	struct page_check_walk pcw = {
+		.page = old_page,
+		.vma = vma,
+		.address = addr,
+	};
 	int err;
 	/* For mmu_notifiers */
 	const unsigned long mmun_start = addr;
 	const unsigned long mmun_end   = addr + PAGE_SIZE;
 	struct mem_cgroup *memcg;
 
+	VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page);
+
 	err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg,
 			false);
 	if (err)
@@ -171,11 +176,11 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 	err = -EAGAIN;
-	ptep = page_check_address(old_page, mm, addr, &ptl, 0);
-	if (!ptep) {
+	if (!page_check_walk(&pcw)) {
 		mem_cgroup_cancel_charge(new_page, memcg, false);
 		goto unlock;
 	}
+	VM_BUG_ON_PAGE(addr != pcw.address, old_page);
 
 	get_page(new_page);
 	page_add_new_anon_rmap(new_page, vma, addr, false);
@@ -187,14 +192,15 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 		inc_mm_counter(mm, MM_ANONPAGES);
 	}
 
-	flush_cache_page(vma, addr, pte_pfn(*ptep));
-	ptep_clear_flush_notify(vma, addr, ptep);
-	set_pte_at_notify(mm, addr, ptep, mk_pte(new_page, vma->vm_page_prot));
+	flush_cache_page(vma, addr, pte_pfn(*pcw.pte));
+	ptep_clear_flush_notify(vma, addr, pcw.pte);
+	set_pte_at_notify(mm, addr, pcw.pte,
+			mk_pte(new_page, vma->vm_page_prot));
 
 	page_remove_rmap(old_page, false);
 	if (!page_mapped(old_page))
 		try_to_free_swap(old_page);
-	pte_unmap_unlock(ptep, ptl);
+	page_check_walk_done(&pcw);
 
 	if (vma->vm_flags & VM_LOCKED)
 		munlock_vma_page(old_page);
-- 
2.11.0

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