mm: call arch_swap_restore() from do_swap_page()

Commit c145e0b ("mm: streamline COW logic in do_swap_page()") moved
the call to swap_free() before the call to set_pte_at(), which meant that
the MTE tags could end up being freed before set_pte_at() had a chance to
restore them.  Fix it by adding a call to the arch_swap_restore() hook
before the call to swap_free().

Link: https://lkml.kernel.org/r/[email protected]
Link: https://linux-review.googlesource.com/id/I6470efa669e8bd2f841049b8c61020c510678965
Fixes: c145e0b ("mm: streamline COW logic in do_swap_page()")
Signed-off-by: Peter Collingbourne <[email protected]>
Reported-by: Qun-wei Lin <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Acked-by: David Hildenbrand <[email protected]>
Acked-by: "Huang, Ying" <[email protected]>
Reviewed-by: Steven Price <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Cc: <[email protected]>	[6.1+]
Signed-off-by: Andrew Morton <[email protected]>

mm/memory.c

@@ -3950,6 +3950,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		}
 	}
 
+	/*
+	 * Some architectures may have to restore extra metadata to the page
+	 * when reading from swap. This metadata may be indexed by swap entry
+	 * so this must be called before swap_free().
+	 */
+	arch_swap_restore(entry, folio);
+
 	/*
 	 * Remove the swap entry and conditionally try to free up the swapcache.
 	 * We're already holding a reference on the page but haven't mapped it