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Subject[PATCH v3 1/3] mm: Call arch_swap_restore() from do_swap_page()
From
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/I6470efa669e8bd2f841049b8c61020c510678965
Cc: <stable@vger.kernel.org> # 6.1
Fixes: c145e0b47c77 ("mm: streamline COW logic in do_swap_page()")
Reported-by: Qun-wei Lin (林群崴) <Qun-wei.Lin@mediatek.com>
Closes: 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 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)
}
}

+ /*
+ * 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
--
2.40.1.606.ga4b1b128d6-goog
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