mm/huge_memory.c: use helper function migration_entry_to_page()

It's more recommended to use helper function migration_entry_to_page()
to get the page via migration entry.  We can also enjoy the PageLocked()
check there.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Thomas Hellstrm (Intel) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: yuleixzhang <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/huge_memory.c

@@ -1693,7 +1693,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 
 			VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
 			entry = pmd_to_swp_entry(orig_pmd);
-			page = pfn_to_page(swp_offset(entry));
+			page = migration_entry_to_page(entry);
 			flush_needed = 0;
 		} else
 			WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
@@ -2101,7 +2101,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 		swp_entry_t entry;
 
 		entry = pmd_to_swp_entry(old_pmd);
-		page = pfn_to_page(swp_offset(entry));
+		page = migration_entry_to_page(entry);
 		write = is_write_migration_entry(entry);
 		young = false;
 		soft_dirty = pmd_swp_soft_dirty(old_pmd);