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From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <yang.shi@linux.alibaba.com>,
	mtk.manpages@gmail.com, akpm@linux-foundation.org,
	linux-man@vger.kernel.org, linux-api@vger.kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH] move_pages.2: Returning positive value is a new error case
Date: Thu, 30 Jan 2020 13:02:53 +0100	[thread overview]
Message-ID: <20200130120253.GU24244@dhcp22.suse.cz> (raw)
In-Reply-To: <f276d8ec-b1be-4f8e-792b-5c3ca2de4714@suse.cz>

On Thu 30-01-20 10:06:28, Vlastimil Babka wrote:
> On 1/29/20 10:48 PM, Yang Shi wrote:
> > Since commit a49bd4d71637 ("mm, numa: rework do_pages_move"),
> > the semantic of move_pages() has changed to return the number of
> > non-migrated pages if they were result of a non-fatal reasons (usually a
> > busy page).  This was an unintentional change that hasn't been noticed
> > except for LTP tests which checked for the documented behavior.
> > 
> > There are two ways to go around this change.  We can even get back to the
> > original behavior and return -EAGAIN whenever migrate_pages is not able
> 
> The manpage says EBUSY, not EAGAIN? And should its description be
> updated too?

The idea was that we _could_ return EAGAIN from the syscall if
migrate_pages > 0.

> I.e. that it's no longer returned since 4.17?

I am pretty sure this will require a deeper consideration. Do we return
EIO/EINVAL?
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2020-01-30 12:02 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-29 21:48 [v2 PATCH] move_pages.2: Returning positive value is a new error case Yang Shi
2020-01-30  9:06 ` Vlastimil Babka
2020-01-30 12:02   ` Michal Hocko [this message]
2020-01-30 12:56     ` Vlastimil Babka
2020-01-30 13:48       ` Michal Hocko
2020-01-30 17:27         ` Yang Shi

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