From: Oscar Salvador <osalvador@suse.de>
To: Huang Ying <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Zi Yan <ziy@nvidia.com>, Yang Shi <shy828301@gmail.com>
Subject: Re: [PATCH -V2 5/7] migrate_pages(): fix failure counting for THP on -ENOSYS
Date: Mon, 11 Jul 2022 14:26:20 +0200 [thread overview]
Message-ID: <YswW7C5jzQNmeOsL@localhost.localdomain> (raw)
In-Reply-To: <20220711084948.274787-6-ying.huang@intel.com>
On Mon, Jul 11, 2022 at 04:49:46PM +0800, Huang Ying wrote:
> If THP or hugetlbfs page migration isn't supported, unmap_and_move()
> or unmap_and_move_huge_page() will return -ENOSYS. For THP, splitting
> will be tried, but if splitting doesn't succeed, the THP will be left
> in "from" list wrongly. If some other pages are retried, the THP
> migration failure will counted again. This is fixed via moving the
> failure THP from "from" to "ret_pages".
>
> Another issue of the original code is that the unsupported failure
> processing isn't consistent between THP and hugetlbfs page. Make them
> consistent in this patch to make the code easier to be understood too.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> ---
> mm/migrate.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 4bceba143db0..8cce73b7c046 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1192,10 +1192,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
> * tables or check whether the hugepage is pmd-based or not before
> * kicking migration.
> */
> - if (!hugepage_migration_supported(page_hstate(hpage))) {
> - list_move_tail(&hpage->lru, ret);
> + if (!hugepage_migration_supported(page_hstate(hpage)))
> return -ENOSYS;
> - }
>
> if (page_count(hpage) == 1) {
> /* page was freed from under us. So we are done. */
> @@ -1392,6 +1390,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> * page will be put back
> * -EAGAIN: stay on the from list
> * -ENOMEM: stay on the from list
> + * -ENOSYS: stay on the from list
> * Other errno: put on ret_pages list then splice to
> * from list
> */
> @@ -1421,6 +1420,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> }
>
> nr_failed_pages += nr_subpages;
> + list_move_tail(&page->lru, &ret_pages);
I must be missing something, but migrate_pages() calls unmap_and_move_huge_page()
with ret being ret_pages, so
list_move_tail(&hpage->lru, ret) == list_move_tail(&page->lru, &ret_pages)
Yet, you say "This is fixed via moving the failure THP from "from" to "ret_pages"".
/me confused.
--
Oscar Salvador
SUSE Labs
next prev parent reply other threads:[~2022-07-11 12:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-11 8:49 [PATCH -V2 0/7] migrate_pages(): fix several bugs in error path Huang Ying
2022-07-11 8:49 ` [PATCH -V2 1/7] migrate: fix syscall move_pages() return value for failure Huang Ying
2022-07-11 11:52 ` Oscar Salvador
2022-07-12 0:59 ` Huang, Ying
2022-07-11 8:49 ` [PATCH -V2 2/7] migrate_pages(): remove unnecessary list_safe_reset_next() Huang Ying
2022-07-11 11:57 ` Oscar Salvador
2022-07-11 8:49 ` [PATCH -V2 3/7] migrate_pages(): fix THP failure counting for -ENOMEM Huang Ying
2022-07-11 12:01 ` Oscar Salvador
2022-07-11 8:49 ` [PATCH -V2 4/7] migrate_pages(): fix failure counting for THP subpages retrying Huang Ying
2022-07-11 12:13 ` Oscar Salvador
2022-07-11 8:49 ` [PATCH -V2 5/7] migrate_pages(): fix failure counting for THP on -ENOSYS Huang Ying
2022-07-11 12:26 ` Oscar Salvador [this message]
2022-07-13 8:30 ` Huang, Ying
2022-07-11 8:49 ` [PATCH -V2 6/7] migrate_pages(): fix failure counting for THP splitting Huang Ying
2022-07-11 12:39 ` Oscar Salvador
2022-07-11 8:49 ` [PATCH -V2 7/7] migrate_pages(): fix failure counting for retry Huang Ying
2022-07-11 12:52 ` Oscar Salvador
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