+ mm-call-arch_swap_restore-from-do_swap_page.patch added to mm-hotfixes-unstable branch

+ mm-call-arch_swap_restore-from-do_swap_page.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: call arch_swap_restore() from do_swap_page()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-call-arch_swap_restore-from-do_swap_page.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-call-arch_swap_restore-from-do_swap_page.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Peter Collingbourne <pcc@google.com>
Subject: mm: call arch_swap_restore() from do_swap_page()
Date: Mon, 22 May 2023 17:43:08 -0700

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>
---

 mm/memory.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/mm/memory.c~mm-call-arch_swap_restore-from-do_swap_page
+++ a/mm/memory.c
@@ -3954,6 +3954,13 @@ 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.
_

Patches currently in -mm which might be from pcc@google.com are

mm-call-arch_swap_restore-from-do_swap_page.patch