From: Wei Yang <richardw.yang@linux.intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Wei Yang <richardw.yang@linux.intel.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, yang.shi@linux.alibaba.com
Subject: Re: [PATCH 1/8] mm/migrate.c: skip node check if done in last round
Date: Wed, 22 Jan 2020 08:36:50 +0800 [thread overview]
Message-ID: <20200122003650.GA11409@richard> (raw)
In-Reply-To: <20200121084205.GD29276@dhcp22.suse.cz>
On Tue, Jan 21, 2020 at 09:42:05AM +0100, Michal Hocko wrote:
>On Tue 21-01-20 06:25:40, Wei Yang wrote:
>> On Mon, Jan 20, 2020 at 10:36:46AM +0100, Michal Hocko wrote:
>> >On Sun 19-01-20 11:06:29, Wei Yang wrote:
>> >> Before move page to target node, we would check if the node id is valid.
>> >> In case we would try to move pages to the same target node, it is not
>> >> necessary to do the check each time.
>> >>
>> >> This patch tries to skip the check if the node has been checked.
>> >>
>> >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>> >> ---
>> >> mm/migrate.c | 19 +++++++++++--------
>> >> 1 file changed, 11 insertions(+), 8 deletions(-)
>> >>
>> >> diff --git a/mm/migrate.c b/mm/migrate.c
>> >> index 430fdccc733e..ba7cf4fa43a0 100644
>> >> --- a/mm/migrate.c
>> >> +++ b/mm/migrate.c
>> >> @@ -1612,15 +1612,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>> >> goto out_flush;
>> >> addr = (unsigned long)untagged_addr(p);
>> >>
>> >> - err = -ENODEV;
>> >> - if (node < 0 || node >= MAX_NUMNODES)
>> >> - goto out_flush;
>> >> - if (!node_state(node, N_MEMORY))
>> >> - goto out_flush;
>> >> + /* Check node if it is not checked. */
>> >> + if (current_node == NUMA_NO_NODE || node != current_node) {
>> >> + err = -ENODEV;
>> >> + if (node < 0 || node >= MAX_NUMNODES)
>> >> + goto out_flush;
>> >> + if (!node_state(node, N_MEMORY))
>> >> + goto out_flush;
>> >
>> >This makes the code harder to read IMHO. The original code checks the
>> >valid node first and it doesn't conflate that with the node caching
>> >logic which your change does.
>> >
>>
>> I am sorry, would you mind showing me an example about the conflate in my
>> change? I don't get it.
>
>NUMA_NO_NODE is the iteration logic, right? It resets the batching node.
>Node check read from the userspace is an input sanitization. Do not put
>those two into the same checks. More clear now?
Yes, I see your point.
Can we think like this:
On each iteration, we do an input sanitization?
Well, this is a trivial one. If you don't like it, I would remove this.
>--
>Michal Hocko
>SUSE Labs
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2020-01-22 0:36 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 [this message]
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
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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