diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
index faf950189bd7..568d5a493876 100644
--- a/fs/erofs/zdata.h
+++ b/fs/erofs/zdata.h
@@ -148,22 +148,22 @@ static inline void z_erofs_onlinepage_init(struct page *page)
 static inline void z_erofs_onlinepage_fixup(struct page *page,
 	uintptr_t index, bool down)
 {
-	unsigned long *p, o, v, id;
-repeat:
-	p = &page_private(page);
-	o = READ_ONCE(*p);
+	union z_erofs_onlinepage_converter u = { .v = &page_private(page) };
+	int orig, orig_index, val;
 
-	id = o >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
-	if (id) {
+repeat:
+	orig = atomic_read(u.o);
+	orig_index = orig >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
+	if (orig_index) {
 		if (!index)
 			return;
 
-		DBG_BUGON(id != index);
+		DBG_BUGON(orig_index != index);
 	}
 
-	v = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) |
-		((o & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
-	if (cmpxchg(p, o, v) != o)
+	val = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) |
+		((orig & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
+	if (atomic_cmpxchg(u.o, orig, val) != orig)
 		goto repeat;
 }