From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richardw.yang@linux.intel.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, yang.shi@linux.alibaba.com
Subject: Re: [PATCH 6/8] mm/migrate.c: handle same node and add failure in the same way
Date: Mon, 20 Jan 2020 11:01:08 +0100 [thread overview]
Message-ID: <20200120100108.GQ18451@dhcp22.suse.cz> (raw)
In-Reply-To: <20200119030636.11899-7-richardw.yang@linux.intel.com>
On Sun 19-01-20 11:06:34, Wei Yang wrote:
> When page is not queued for migration, there are two possible cases:
>
> * page already on the target node
> * failed to add to migration queue
>
> Current code handle them differently, this leads to a behavior
> inconsistency.
>
> Usually for each page's status, we just do store for once. While for the
> page already on the target node, we might store the node information for
> twice:
>
> * once when we found the page is on the target node
> * second when moving the pages to target node successfully after above
> action
>
> The reason is even we don't add the page to pagelist, but store_status()
> does store in a range which still contains the page.
>
> This patch handles these two cases in the same way to reduce this
> inconsistency and also make the code a little easier to read.
Yeah, the improvement is really marginal. I do not feel strongly one way
or another.
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/migrate.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 46a5697b7fc6..aee5aeb082c4 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1657,18 +1657,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
> err = add_page_for_migration(mm, addr, current_node,
> &pagelist, flags & MPOL_MF_MOVE_ALL);
>
> - if (!err) {
> - /* The page is already on the target node */
> - err = store_status(status, i, current_node, 1);
> - if (err)
> - goto out_flush;
> - continue;
> - } else if (err > 0) {
> + if (err > 0) {
> /* The page is successfully queued for migration */
> continue;
> }
>
> - err = store_status(status, i, err, 1);
> + /*
> + * Two possible cases for err here:
> + * == 0: page is already on the target node, then store
> + * current_node to status
> + * < 0: failed to add page to list, then store err to status
> + */
> + err = store_status(status, i, err ? : current_node, 1);
> if (err)
> goto out_flush;
>
> --
> 2.17.1
>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-01-20 10:01 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-19 3:06 [PATCH 0/8] mm/migrate.c: cleanup on do_pages_move() Wei Yang
2020-01-19 3:06 ` [PATCH 1/8] mm/migrate.c: skip node check if done in last round Wei Yang
2020-01-20 9:36 ` Michal Hocko
2020-01-20 22:25 ` Wei Yang
2020-01-21 8:42 ` Michal Hocko
2020-01-22 0:36 ` Wei Yang
2020-01-22 8:16 ` Michal Hocko
2020-01-19 3:06 ` [PATCH 2/8] mm/migrate.c: not necessary to check start and i Wei Yang
2020-01-19 22:14 ` David Rientjes
2020-01-20 0:31 ` Wei Yang
2020-01-20 9:45 ` Michal Hocko
2020-01-19 3:06 ` [PATCH 3/8] mm/migrate.c: reform the last call on do_move_pages_to_node() Wei Yang
2020-01-20 9:46 ` Michal Hocko
2020-01-20 22:27 ` Wei Yang
2020-01-19 3:06 ` [PATCH 4/8] mm/migrate.c: wrap do_move_pages_to_node() and store_status() Wei Yang
2020-01-20 9:49 ` Michal Hocko
2020-01-19 3:06 ` [PATCH 5/8] mm/migrate.c: check pagelist in move_pages_and_store_status() Wei Yang
2020-01-20 9:52 ` Michal Hocko
2020-01-19 3:06 ` [PATCH 6/8] mm/migrate.c: handle same node and add failure in the same way Wei Yang
2020-01-20 10:01 ` Michal Hocko [this message]
2020-01-19 3:06 ` [PATCH 7/8] mm/migrate.c: move page on next iteration Wei Yang
2020-01-20 10:02 ` Michal Hocko
2020-01-21 1:22 ` Wei Yang
2020-01-21 8:43 ` Michal Hocko
2020-01-22 0:40 ` Wei Yang
2020-01-22 8:17 ` Michal Hocko
2020-01-19 3:06 ` [PATCH 8/8] mm/migrate.c: use break instead of goto out_flush Wei Yang
2020-01-20 10:03 ` Michal Hocko
2020-01-21 1:22 ` Wei Yang
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