Re: MADV_DONTNEED semantics? Was: [RFC PATCH] mm: madvise: Ignore repeated MADV_DONTNEED hints

From: Michael Kerrisk (man-pages)
Date: Mon Feb 09 2015 - 04:13:28 EST

Hello Minchan

On 02/09/2015 07:46 AM, Minchan Kim wrote:
> Hello, Michael
> On Fri, Feb 06, 2015 at 04:41:12PM +0100, Michael Kerrisk (man-pages) wrote:
>> On 02/05/2015 02:07 AM, Minchan Kim wrote:
>>> Hello,
>>> On Wed, Feb 04, 2015 at 08:24:27PM +0100, Michael Kerrisk (man-pages) wrote:
>>>> On 4 February 2015 at 18:02, Vlastimil Babka <vbabka@xxxxxxx> wrote:
>>>>> On 02/04/2015 03:00 PM, Michael Kerrisk (man-pages) wrote:


>>> And we should make error section, too.
>>> "locked" covers mlock(2) and you said you will add hugetlb. Then,
>>> VM_PFNMAP? In that case, it fails. How can we say about VM_PFNMAP?
>>> special mapping for some drivers?
>> I'm open for offers on what to add.
> I suggests from quote "LWN"
> "*special mapping* which is not made up of "normal" pages.
> It is usually created by device drivers which map special memory areas
> into user space"

Thanks. I've added mention of VM_PFNMAP in the discussion of both
MADV_DONTNEED and MADV_REMOVE, and noted that both of those
operations will give an error when applied to VM_PFNMAP pages.



Michael Kerrisk
Linux man-pages maintainer;
Linux/UNIX System Programming Training:
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