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Subject: Re: [PATCH v2 5/9] mm, hwpoison: make unpoison aware of raw error
 info in hwpoisoned hugepage
To:     Naoya Horiguchi <nao.horiguchi@gmail.com>, <linux-mm@kvack.org>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Liu Shixin <liushixin2@huawei.com>,
        Yang Shi <shy828301@gmail.com>,
        Oscar Salvador <osalvador@suse.de>,
        Muchun Song <songmuchun@bytedance.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        <linux-kernel@vger.kernel.org>
References: <20220623235153.2623702-1-naoya.horiguchi@linux.dev>
 <20220623235153.2623702-6-naoya.horiguchi@linux.dev>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <ea1d17d8-89df-04b7-29e8-0da53dbd3312@huawei.com>
Date:   Mon, 27 Jun 2022 16:32:48 +0800
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On 2022/6/24 7:51, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@nec.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@nec.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);
>  	}
>