From: John Hubbard <jhubbard@nvidia.com>
To: Wei Yang <richardw.yang@linux.intel.com>
Cc: <akpm@linux-foundation.org>, <yang.shi@linux.alibaba.com>,
<vbabka@suse.cz>, <cl@linux.com>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>, <mhocko@kernel.org>
Subject: Re: [Patch v2] mm/migrate.c: also overwrite error when it is bigger than zero
Date: Tue, 21 Jan 2020 11:33:16 -0800 [thread overview]
Message-ID: <0aa42c19-4144-5c7a-10f5-162b1b068d4c@nvidia.com> (raw)
In-Reply-To: <20200121023408.GA3636@richard>
On 1/20/20 6:34 PM, Wei Yang wrote:
> On Tue, Jan 21, 2020 at 09:53:26AM +0800, Wei Yang wrote:
>> On Sun, Jan 19, 2020 at 02:57:53PM +0800, Wei Yang wrote:
>>> If we get here after successfully adding page to list, err would be
>>> 1 to indicate the page is queued in the list.
>>>
>>> Current code has two problems:
>>>
>>> * on success, 0 is not returned
>>> * on error, if add_page_for_migratioin() return 1, and the following err1
>>> from do_move_pages_to_node() is set, the err1 is not returned since err
>>> is 1
>>>
>>> And these behaviors break the user interface.
>>>
>>> Fixes: e0153fc2c760 ("mm: move_pages: return valid node id in status if the
>>> page is already on the target node").
The Fixes tag should be different, right? Because I don't think that
commit introduced this problem.
thanks,
--
John Hubbard
NVIDIA
>>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>>>
>>> ---
>>> v2:
>>> * put more words to explain the error case
>>> ---
>>> mm/migrate.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/mm/migrate.c b/mm/migrate.c
>>> index 86873b6f38a7..430fdccc733e 100644
>>> --- a/mm/migrate.c
>>> +++ b/mm/migrate.c
>>> @@ -1676,7 +1676,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>>> err1 = do_move_pages_to_node(mm, &pagelist, current_node);
>>> if (!err1)
>>> err1 = store_status(status, start, current_node, i - start);
>>> - if (!err)
>>> + if (err >= 0)
>>> err = err1;
>>
>> Ok, as mentioned by Yang and Michal, only err == 0 means no error.
>>
>> Sounds this regression should be fixed in another place. Let me send out
>> another patch.
>>
>
> Hmm... I took another look into the case, this fix should work.
>
> But yes, the semantic here is a little confusion. Look forward your comments
> here.
>
>>> out:
>>> return err;
>>> --
>>> 2.17.1
>>
>> --
>> Wei Yang
>> Help you, Help me
>
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2020-01-21 19:33 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-19 6:57 [Patch v2] mm/migrate.c: also overwrite error when it is bigger than zero Wei Yang
2020-01-21 1:53 ` Wei Yang
2020-01-21 2:34 ` Wei Yang
2020-01-21 19:33 ` John Hubbard [this message]
2020-01-22 0:42 ` Wei Yang
2020-01-22 1:29 ` John Hubbard
2020-01-21 19:30 ` Yang Shi
2020-01-22 0:41 ` Wei Yang
2020-01-24 7:21 ` Michal Hocko
2020-01-24 14:15 ` Wei Yang
2020-01-24 14:46 ` Michal Hocko
2020-01-24 15:28 ` Wei Yang
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