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Date:   Mon, 22 May 2023 17:43:08 -0700
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Subject: [PATCH v4 1/3] mm: Call arch_swap_restore() from do_swap_page()
From:   Peter Collingbourne <pcc@google.com>
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     Peter Collingbourne <pcc@google.com>,
        "=?UTF-8?q?Qun-wei=20Lin=20=28=E6=9E=97=E7=BE=A4=E5=B4=B4=29?=" 
        <Qun-wei.Lin@mediatek.com>, linux-arm-kernel@lists.infradead.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        "surenb@google.com" <surenb@google.com>,
        "david@redhat.com" <david@redhat.com>,
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        "=?UTF-8?q?Kuan-Ying=20Lee=20=28=E6=9D=8E=E5=86=A0=E7=A9=8E=29?=" 
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        vincenzo.frascino@arm.com,
        Alexandru Elisei <alexandru.elisei@arm.com>, will@kernel.org,
        eugenis@google.com, Steven Price <steven.price@arm.com>,
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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().

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I6470efa669e8bd2f841049b8c61=
020c510678965
Cc: <stable@vger.kernel.org> # 6.1
Fixes: c145e0b47c77 ("mm: streamline COW logic in do_swap_page()")
Reported-by: Qun-wei Lin (=E6=9E=97=E7=BE=A4=E5=B4=B4) <Qun-wei.Lin@mediate=
k.com>
Closes: https://lore.kernel.org/all/5050805753ac469e8d727c797c2218a9d780d43=
4.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>
---
v2:
- Call arch_swap_restore() directly instead of via arch_do_swap_page()

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

diff --git a/mm/memory.c b/mm/memory.c
index f69fbc251198..fc25764016b3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3932,6 +3932,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		}
 	}
=20
+	/*
+	 * 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
--=20
2.40.1.698.g37aff9b760-goog