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Subject: Re: [PATCH] mm/migrate.c: also overwrite error when it is bigger than
 zero
To:     Wei Yang <richardw.yang@linux.intel.com>,
        Yang Shi <shy828301@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <20200117074534.25324-1-richardw.yang@linux.intel.com>
 <20200117222740.GB29229@richard>
 <CAHbLzkoYH1_JHH99pnopj_v=Wb=UEGMS9dJs1J6GZn0=6F4SJw@mail.gmail.com>
 <20200117234829.GA2844@richard>
From:   Mike Kravetz <mike.kravetz@oracle.com>
Message-ID: <cc48623f-329b-ec43-a85a-d9a914ca87bc@oracle.com>
Date:   Fri, 17 Jan 2020 17:38:10 -0800
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On 1/17/20 3:48 PM, Wei Yang wrote:
> This is another point I think current code is not working well. And actually,
> the behavior is not well defined or our kernel is broken for a while.
> 
> When you look at the man page, it says:
> 
>     RETURN VALUE
>            On success move_pages() returns zero.  On error, it returns -1, and sets errno to indicate the error
> 

Is this from your migrate_pages(2) man page?

The latest version of the migrate_pages(2) man page in the git repo has this
for RETURN VALUE.

RETURN VALUE
       On  success  migrate_pages() returns the number of pages that could not
       be moved (i.e., a return of zero means that all pages were successfully
       moved).  On error, it returns -1, and sets errno to indicate the error.

-- 
Mike Kravetz