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Message-ID: <20210112100213.GK22493@dhcp22.suse.cz>
Date: Tue, 12 Jan 2021 11:02:13 +0100
From: Michal Hocko <mhocko@...e.com>
To: Muchun Song <songmuchun@...edance.com>
Cc: mike.kravetz@...cle.com, akpm@...ux-foundation.org,
n-horiguchi@...jp.nec.com, ak@...ux.intel.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v3 3/6] mm: hugetlb: fix a race between freeing and
dissolving the page
On Sun 10-01-21 20:40:14, Muchun Song wrote:
[...]
> @@ -1770,6 +1788,14 @@ int dissolve_free_huge_page(struct page *page)
> int nid = page_to_nid(head);
> if (h->free_huge_pages - h->resv_huge_pages == 0)
> goto out;
> +
> + /*
> + * We should make sure that the page is already on the free list
> + * when it is dissolved.
> + */
> + if (unlikely(!PageHugeFreed(head)))
> + goto out;
> +
Do you really want to report EBUSY in this case? This doesn't make much
sense to me TBH. I believe you want to return 0 same as when you race
and the page is no longer PageHuge.
> /*
> * Move PageHWPoison flag from head page to the raw error page,
> * which makes any subpages rather than the error page reusable.
> --
> 2.11.0
--
Michal Hocko
SUSE Labs
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