Re: [PATCH v4] mmap.2: MAP_FIXED updated documentation

From: Michal Hocko
Date: Mon Dec 11 2017 - 04:03:14 EST


On Sun 10-12-17 18:22:05, John Hubbard wrote:
> On 12/10/2017 02:31 AM, Michal Hocko wrote:
> > On Tue 05-12-17 19:14:34, john.hubbard@xxxxxxxxx wrote:
> >> From: John Hubbard <jhubbard@xxxxxxxxxx>
> >>
> >> Previously, MAP_FIXED was "discouraged", due to portability
> >> issues with the fixed address. In fact, there are other, more
> >> serious issues. Also, alignment requirements were a bit vague.
> >> So:
> >>
> >> -- Expand the documentation to discuss the hazards in
> >> enough detail to allow avoiding them.
> >>
> >> -- Mention the upcoming MAP_FIXED_SAFE flag.
> >>
> >> -- Enhance the alignment requirement slightly.
> >>
> >> Some of the wording is lifted from Matthew Wilcox's review
> >> (the "Portability issues" section). The alignment requirements
> >> section uses Cyril Hrubis' wording, with light editing applied.
> >>
> >> Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> >> Suggested-by: Cyril Hrubis <chrubis@xxxxxxx>
> >> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> >
> > Would you mind if I take this patch and resubmit it along with my
> > MAP_FIXED_SAFE (or whatever name I will end up with) next week?
> >
> > Acked-by: Michal Hocko <mhocko@xxxxxxxx>
>
> Sure, that works for me. A tiny complication: I see that Michael
> Kerrisk has already applied the much smaller v2 of this patch (the
> one that "no longer discourages" the option, but that's all), as:
>
> ffa518803e14 mmap.2: MAP_FIXED is no longer discouraged
>
> so this one here will need to be adjusted slightly to merge
> gracefully. Let me know if you want me to respin, or if you
> want to handle the merge.

Yes, please respin.
--
Michal Hocko
SUSE Labs