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From:   "Huang, Ying" <ying.huang@intel.com>
To:     Peter Collingbourne <pcc@google.com>
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Subject: Re: [PATCH v3 1/3] mm: Call arch_swap_restore() from do_swap_page()
References: <20230517022115.3033604-1-pcc@google.com>
        <20230517022115.3033604-2-pcc@google.com>
Date:   Wed, 17 May 2023 11:40:58 +0800
In-Reply-To: <20230517022115.3033604-2-pcc@google.com> (Peter Collingbourne's
        message of "Tue, 16 May 2023 19:21:11 -0700")
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Peter Collingbourne <pcc@google.com> writes:

> 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/I6470efa669e8bd2f841049b8c=
61020c510678965
> 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@media=
tek.com>
> Closes: https://lore.kernel.org/all/5050805753ac469e8d727c797c2218a9d780d=
434.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)
>  		}
>  	}
>=20=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

Should you add

Suggested-by: David Hildenbrand <david@redhat.com>

for 1/3 and 2/3.

It looks good for me for swap code related part.  Feel free to add

Acked-by: "Huang, Ying" <ying.huang@intel.com>

to 1/3 and 2/3.

Best Regards,
Huang, Ying