From: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>
To: Muchun Song <songmuchun@bytedance.com>
Cc: "mike.kravetz@oracle.com" <mike.kravetz@oracle.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"hillf.zj@alibaba-inc.com" <hillf.zj@alibaba-inc.com>,
"n-horiguchi@ah.jp.nec.com" <n-horiguchi@ah.jp.nec.com>,
"ak@linux.intel.com" <ak@linux.intel.com>,
"yongjun_wei@trendmicro.com.cn" <yongjun_wei@trendmicro.com.cn>,
"mhocko@suse.cz" <mhocko@suse.cz>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/6] mm: hugetlb: add return -EAGAIN for dissolve_free_huge_page
Date: Tue, 5 Jan 2021 06:37:57 +0000 [thread overview]
Message-ID: <20210105063757.GA7244@hori.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <20210104065843.5658-4-songmuchun@bytedance.com>
On Mon, Jan 04, 2021 at 02:58:41PM +0800, Muchun Song wrote:
> When dissolve_free_huge_page() races with __free_huge_page(), we can
> do a retry. Because the race window is small.
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
> mm/hugetlb.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 72608008f8b4..db00ae375d2a 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1763,10 +1763,11 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
> * nothing for in-use hugepages and non-hugepages.
> * This function returns values like below:
> *
> - * -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
> - * (allocated or reserved.)
> - * 0: successfully dissolved free hugepages or the page is not a
> - * hugepage (considered as already dissolved)
> + * -EAGAIN: race with __free_huge_page() and can do a retry
> + * -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
> + * (allocated or reserved.)
> + * 0: successfully dissolved free hugepages or the page is not a
> + * hugepage (considered as already dissolved)
> */
> int dissolve_free_huge_page(struct page *page)
> {
> @@ -1815,8 +1816,10 @@ int dissolve_free_huge_page(struct page *page)
> * We should make sure that the page is already on the free list
> * when it is dissolved.
> */
> - if (unlikely(!PageHugeFreed(head)))
> + if (unlikely(!PageHugeFreed(head))) {
> + rc = -EAGAIN;
> goto out;
> + }
If dissolve_free_huge_page() races with __free_huge_page() and we detect
it with this check, the hugepage is expected to be freed or dissolved by
__free_huge_page(), so is it enough just to return with rc = 0 without retrying?
Thanks,
Naoya Horiguchi
>
> /*
> * Move PageHWPoison flag from head page to the raw error page,
> @@ -1857,7 +1860,10 @@ int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
>
> for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
> page = pfn_to_page(pfn);
> +retry:
> rc = dissolve_free_huge_page(page);
> + if (rc == -EAGAIN)
> + goto retry;
> if (rc)
> break;
> }
> --
> 2.11.0
>
next prev parent reply other threads:[~2021-01-05 6:40 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 6:58 [PATCH 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one Muchun Song
2021-01-04 6:58 ` [PATCH 2/6] hugetlbfs: fix cannot migrate the fallocated HugeTLB page Muchun Song
2021-01-04 22:38 ` Mike Kravetz
2021-01-05 2:44 ` [External] " Muchun Song
2021-01-05 22:27 ` Mike Kravetz
2021-01-06 2:57 ` Muchun Song
2021-01-04 6:58 ` [PATCH 3/6] mm: hugetlb: fix a race between freeing and dissolving the page Muchun Song
2021-01-05 0:00 ` Mike Kravetz
2021-01-05 2:55 ` [External] " Muchun Song
2021-01-05 23:22 ` Mike Kravetz
2021-01-06 6:05 ` Muchun Song
2021-01-05 6:12 ` Muchun Song
2021-01-04 6:58 ` [PATCH 4/6] mm: hugetlb: add return -EAGAIN for dissolve_free_huge_page Muchun Song
2021-01-05 1:32 ` Mike Kravetz
2021-01-05 3:14 ` [External] " Muchun Song
2021-01-05 3:46 ` Muchun Song
2021-01-06 0:07 ` Mike Kravetz
2021-01-05 6:37 ` HORIGUCHI NAOYA(堀口 直也) [this message]
2021-01-05 7:10 ` Muchun Song
2021-01-05 7:30 ` HORIGUCHI NAOYA(堀口 直也)
2021-01-04 6:58 ` [PATCH 5/6] mm: hugetlb: fix a race between isolating and freeing page Muchun Song
2021-01-05 1:42 ` Mike Kravetz
2021-01-04 6:58 ` [PATCH 6/6] mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active Muchun Song
2021-01-05 1:50 ` Mike Kravetz
2021-01-04 22:17 ` [PATCH 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one Mike Kravetz
2021-01-05 16:58 ` David Hildenbrand
2021-01-05 18:04 ` Yang Shi
2021-01-05 18:05 ` David Hildenbrand
2021-01-05 18:04 ` Yang Shi
2021-01-06 16:11 ` Michal Hocko
2021-01-06 16:12 ` Michal Hocko
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