linux-kernel - Re: [PATCH v4 2/2] mm/hwpoison: Add in-use hugepage hwpoison filter judgement

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Date:   Mon, 21 Feb 2022 20:05:28 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     luofei <luofei@...cloud.com>, <naoya.horiguchi@....com>,
        <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] mm/hwpoison: Add in-use hugepage hwpoison filter
 judgement

On 2022/2/21 10:15, luofei wrote:
> After successfully obtaining the reference count of the huge
> page, it is still necessary to call hwpoison_filter() to make a
> filter judgement, otherwise the filter hugepage will be unmaped
> and the related process may be killed.
> 

LGTM. Thanks.

Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>

BTW: It seems there is also another missing call to hwpoison_filter() when we
encounter free_buddy_page in memory_failure(). But I'am not sure.

> Signed-off-by: luofei <luofei@...cloud.com>
> ---
>  mm/memory-failure.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 59d6d939a752..17a7b0a94ab9 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1548,6 +1548,17 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags)
>  	lock_page(head);
>  	page_flags = head->flags;
>  
> +	if (hwpoison_filter(p)) {
> +		if (TestClearPageHWPoison(head))
> +			num_poisoned_pages_dec();
> +		put_page(p);
> +		if (flags & MF_MCE_HANDLE)
> +			res = -EHWPOISON;
> +		else
> +			res = 0;
> +		goto out;
> +	}
> +
>  	/*
>  	 * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so
>  	 * simply disable it. In order to make it work properly, we need
>