linux-kernel - Re: [PATCH] mm/hwpoison: dissolve error hugepages of file mapping

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Message-ID: <YPBSwEdagjXjx2jO@casper.infradead.org>
Date:   Thu, 15 Jul 2021 16:22:40 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Bin Wang <wangbin224@...wei.com>
Cc:     linux-mm@...ck.org, naoya.horiguchi@....com,
        akpm@...ux-foundation.org, wuxu.wu@...wei.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/hwpoison: dissolve error hugepages of file mapping

On Thu, Jul 15, 2021 at 11:08:52PM +0800, Bin Wang wrote:
> We handle error on hugetlb file with hugetlbfs_error_remove_page(),
> which removes the error hugepages from page cache. And with the
> HWPoison flag in head page, it is safe to free the error hugepages
> and dissolve it.

How is that safe?  If you're going to dissolve the huge page, you
need to figure out which subpage needs to have the HWPoison flag set.