linux-kernel - RE: [PATCH v3 1/2] mm, hwpoison: Try to recover from copy-on write faults

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Date:   Fri, 28 Oct 2022 16:09:08 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Miaohe Lin <linmiaohe@...wei.com>,
        Alexander Potapenko <glider@...gle.com>
CC:     Matthew Wilcox <willy@...radead.org>,
        Shuai Xue <xueshuai@...ux.alibaba.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: RE: [PATCH v3 1/2] mm, hwpoison: Try to recover from copy-on write
 faults

>> +	vfrom = kmap_local_page(from);
>> +	vto = kmap_local_page(to);
>> +	ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE);
>
> In copy_user_highpage(), kmsan_unpoison_memory(page_address(to), PAGE_SIZE) is done after the copy when
> __HAVE_ARCH_COPY_USER_HIGHPAGE isn't defined. Do we need to do something similar here? But I'm not familiar
> with kmsan, so I can easy be wrong.

It looks like that kmsan_unpoison_memory() call was added recently, after I copied
copy_user_highpage() to create copy_mc_user_highpage(). I'm not familiar with
kmsan either. Adding Alexander to this thread since they added that code.

> Anyway, this patch looks good to me. Thanks.
>
> Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>

Thanks for the review.

-Tony