Re: [PATCH v14 4/8] mm/hwpoison: return -EFAULT when copy fail in copy_mc_[user]_highpage()

[Shuai Xue]

On 5/18/26 4:49 PM, Ruidong Tian wrote:
> From: Tong Tiangen <tongtiangen@xxxxxxxxxx>
>
> Currently, copy_mc_[user]_highpage() returns zero on success, or in case
> of failures, the number of bytes that weren't copied.
>
> While tracking the number of not copied works fine for x86 and PPC, There
> are some difficulties in doing the same thing on ARM64 because there is no
> available caller-saved register in copy_page()(lib/copy_page.S) to save
> "bytes not copied", and the following copy_mc_page() will also encounter
> the same problem.
>
> Consider the caller of copy_mc_[user]_highpage() cannot do any processing
> on the remaining data(The page has hardware errors), they only check if
> copy was succeeded or not, make the interface more generic by using an
> error code when copy fails (-EFAULT) or return zero on success.
>
> Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>

Reviewed-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
Thanks.
Shuai