Re: [PATCH v17 1/7] mm: support madvise(MADV_FREE)

[Minchan Kim <minchan@kernel.org>]

Hello, Michael

On Tue, Feb 03, 2015 at 05:39:24PM +0100, Michael Kerrisk (man-pages) wrote:
> Hello Minchan (and Michal)
> 
> I did not see this patch until just now when Michael explicitly
> mentioned it in another discussion because
> (a) it was buried in an LMKL thread that started a topic
>     that was not about a man-pages patch.
> (b) linux-man@ was not CCed.

Sorry about that.

> 
> When resubmitting this patch, could you please To:me and CC linux-man@
> and give the mail a suitable subject line indicating a man-pages patch.

Sure.

> 
> On 12/05/2014 09:32 AM, Michal Hocko wrote:
> > On Fri 05-12-14 16:08:16, Minchan Kim wrote:
> > [...]
> >> From cfa212d4fb307ae772b08cf564cab7e6adb8f4fc Mon Sep 17 00:00:00 2001
> >> From: Minchan Kim <minchan@kernel.org>
> >> Date: Mon, 1 Dec 2014 08:53:55 +0900
> >> Subject: [PATCH] madvise.2: Document MADV_FREE
> >>
> >> Signed-off-by: Minchan Kim <minchan@kernel.org>
> > 
> > Reviewed-by: Michal Hocko <mhocko@suse.cz>
> > 
> > Thanks!
> > 
> >> ---
> >>  man2/madvise.2 | 12 ++++++++++++
> >>  1 file changed, 12 insertions(+)
> >>
> >> diff --git a/man2/madvise.2 b/man2/madvise.2
> >> index 032ead7..fc1aaca 100644
> >> --- a/man2/madvise.2
> >> +++ b/man2/madvise.2
> >> @@ -265,6 +265,18 @@ file (see
> >>  .BR MADV_DODUMP " (since Linux 3.4)"
> >>  Undo the effect of an earlier
> >>  .BR MADV_DONTDUMP .
> >> +.TP
> >> +.BR MADV_FREE " (since Linux 3.19)"
> >> +Tell the kernel that contents in the specified address range are no
> >> +longer important and the range will be overwritten. When there is
> >> +demand for memory, the system will free pages associated with the
> >> +specified address range. In this instance, the next time a page in the
> >> +address range is referenced, it will contain all zeroes.  Otherwise,
> >> +it will contain the data that was there prior to the MADV_FREE call.
> >> +References made to the address range will not make the system read
> >> +from backing store (swap space) until the page is modified again.
> >> +It works only with private anonymous pages (see
> >> +.BR mmap (2)).
> >>  .SH RETURN VALUE
> >>  On success
> >>  .BR madvise ()
> 
> If I'm reading the conversation right, the initially proposed text 
> was from the BSD man page (which would be okay), but most of the 
> text above seems  to have come straight from the page here:
> http://www.lehman.cuny.edu/cgi-bin/man-cgi?madvise+3
> 
> Right?

True. Solaris man page was really straightforward/clear rather than BSD.

> 
> Unfortunately, I don't think we can use that text. It's from the 
> Solaris man page as far as I can tell, and I doubt that it's 
> under a license that we can use.
> 
> If that's the case, we need to go back and come up with an
> original text. It might draw inspiration from the Solaris page,
> and take actual text from the BSD page (which is under a free
> license), and it might also draw inspiration from Jon Corbet's 
> description at http://lwn.net/Articles/590991/. 
> 
> Could you take another shot this please!

No problem. I will test my essay writing skill.
Thanks. 

> 
> Thanks,
> 
> Michael
> 
> 
> 
> -- 
> Michael Kerrisk
> Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
> Linux/UNIX System Programming Training: http://man7.org/training/

-- 
Kind regards,
Minchan Kim

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