Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 15 May 2023 19:35:12 -0700
In-Reply-To: <20230516023514.2643054-1-pcc@google.com>
Message-Id: <20230516023514.2643054-2-pcc@google.com>
Mime-Version: 1.0
References: <20230516023514.2643054-1-pcc@google.com>
Subject: [PATCH v2 1/2] 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>,
        "=?UTF-8?q?Chinwen=20Chang=20=28=E5=BC=B5=E9=8C=A6=E6=96=87=29?=" 
        <chinwen.chang@mediatek.com>,
        "kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>,
        "=?UTF-8?q?Kuan-Ying=20Lee=20=28=E6=9D=8E=E5=86=A0=E7=A9=8E=29?=" 
        <Kuan-Ying.Lee@mediatek.com>,
        "=?UTF-8?q?Casper=20Li=20=28=E6=9D=8E=E4=B8=AD=E6=A6=AE=29?=" 
        <casper.li@mediatek.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        vincenzo.frascino@arm.com,
        Alexandru Elisei <alexandru.elisei@arm.com>, will@kernel.org,
        eugenis@google.com, Steven Price <steven.price@arm.com>,
        stable@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

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>
Link: https://lore.kernel.org/all/5050805753ac469e8d727c797c2218a9d780d434.=
camel@mediatek.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 01a23ad48a04..a2d9e6952d31 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3914,6 +3914,13 @@ 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
2.40.1.606.ga4b1b128d6-goog