linux-kernel - Re: [PATCH v2 5/9] mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage

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Date:   Mon, 27 Jun 2022 16:32:48 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Naoya Horiguchi <nao.horiguchi@...il.com>, <linux-mm@...ck.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Liu Shixin <liushixin2@...wei.com>,
        Yang Shi <shy828301@...il.com>,
        Oscar Salvador <osalvador@...e.de>,
        Muchun Song <songmuchun@...edance.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/9] mm, hwpoison: make unpoison aware of raw error
 info in hwpoisoned hugepage

On 2022/6/24 7:51, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@....com>
> 
> Raw error info list needs to be removed when hwpoisoned hugetlb is
> unpoisioned.  And unpoison handler needs to know how many errors there
> are in the target hugepage. So add them.
> 
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>

snip

> @@ -2255,7 +2275,7 @@ int unpoison_memory(unsigned long pfn)
>  unlock_mutex:
>  	mutex_unlock(&mf_mutex);
>  	if (!ret || freeit) {
> -		num_poisoned_pages_dec();
> +		num_poisoned_pages_sub(count);

IIUC, num_poisoned_pages will only be incremented once for hugetlb page. If many
subpages are hwpoisoned, they will reach the "else if (res == -EHWPOISON)" path
in try_memory_failure_hugetlb and thus num_poisoned_pages_inc is ignored. Maybe
that should be changed so subpages can contribute to the num_poisoned_pages
or should we just do num_poisoned_pages_dec here? Or am I miss something?

Thanks!

>  		unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
>  				 page_to_pfn(p), &unpoison_rs);
>  	}
>