mm: call arch_swap_restore() from do_swap_page()

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>

diff --git a/mm/memory.c b/mm/memory.c
index 0ae59470302111cbab631fd1ccb84a9d3f99d9e0..01f39e8144effd7ae67be7d7239547af45e95118 100644 (file)
--- a/mm/memory.c
+++ b/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