From: Qian Cai <cai@lca.pw>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>,
fabecassis@nvidia.com, mhocko@suse.com, cl@linux.com,
vbabka@suse.cz, mgorman@techsingularity.net,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [v3 PATCH] mm: move_pages: return valid node id in status if the page is already on the target node
Date: Thu, 5 Dec 2019 18:16:58 -0500 [thread overview]
Message-ID: <4C589824-CA40-41A3-8F2B-C2AA2A924510@lca.pw> (raw)
In-Reply-To: <bd3f2ee5-9cbd-ed4f-9863-8859866da810@nvidia.com>
> On Dec 5, 2019, at 5:41 PM, John Hubbard <jhubbard@nvidia.com> wrote:
>
> Please recall how this started: it was due to a report from a real end user, who was
> seeing a real problem. After a few emails, it was clear that there's not a good
> work around available for cases like this:
>
> * User space calls move_pages(), gets 0 (success) returned, and based on that,
> proceeds to iterate through the status array.
>
> * The status array remains untouched by the move_pages() call, so confusion and
> wrong behavior ensues.
>
> After some further discussion, we decided that the current behavior really is
> incorrect, and that it needs fixing in the kernel. Which this patch does.
Well, that test code itself does not really tell any real world use case. Also, thanks to the discussion, it brought to me it is more obvious and critical that the return code is wrong according to the spec. Then, if that part is taking care of, it would kill two-bird with one stone because there is no need to return status array anymore. Make sense?
next prev parent reply other threads:[~2019-12-05 23:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 18:54 Yang Shi
2019-12-05 19:19 ` Qian Cai
2019-12-05 19:27 ` Yang Shi
2019-12-05 19:34 ` Qian Cai
2019-12-05 22:09 ` Yang Shi
2019-12-05 22:23 ` Qian Cai
2019-12-05 22:41 ` John Hubbard
2019-12-05 23:16 ` Qian Cai [this message]
2019-12-05 23:24 ` John Hubbard
2019-12-05 23:58 ` Qian Cai
2019-12-06 0:04 ` John Hubbard
2019-12-06 0:19 ` Qian Cai
2019-12-06 1:11 ` Yang Shi
2019-12-05 19:45 ` Christopher Lameter
2019-12-05 21:59 ` Yang Shi
2019-12-06 7:35 ` Michal Hocko
2019-12-05 21:27 ` John Hubbard
2019-12-05 22:00 ` Yang Shi
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