[PATCH 6.4 5/8] mm: call arch_swap_restore() from do_swap_page()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Peter Collingbourne <pcc@google.com>

commit 6dca4ac6fc91fd41ea4d6c4511838d37f4e0eab2 upstream.

Commit c145e0b47c77 ("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/20230523004312.1807357-2-pcc@google.com
Link: https://linux-review.googlesource.com/id/I6470efa669e8bd2f841049b8c61020c510678965
Fixes: c145e0b47c77 ("mm: streamline COW logic in do_swap_page()")
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reported-by: Qun-wei Lin <Qun-wei.Lin@mediatek.com>
Closes: https://lore.kernel.org/all/5050805753ac469e8d727c797c2218a9d780d434.camel@mediatek.com/
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>	[6.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/memory.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3933,6 +3933,13 @@ vm_fault_t do_swap_page(struct vm_fault
 	}
 
 	/*
+	 * 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
 	 * yet.