Re: [34-longterm 167/179] futex: Fix regression with read only mappings

[Willy Tarreau <w@1wt.eu>]

On Tue, May 15, 2012 at 12:02:50PM -0400, Paul Gortmaker wrote:
> [Re: [34-longterm 167/179] futex: Fix regression with read only mappings] On 15/05/2012 (Tue 12:51) Peter Zijlstra wrote:
> 
> > On Mon, 2012-05-14 at 21:38 -0700, Hugh Dickins wrote:
> > > I don't know: I'm not NAKking it, I'm just waving a reddish flag,
> > > and hoping that Peter will remember more, and have something more
> > > constructive to say, than I can think of at this moment. 
> > 
> > Ha! you're very optimistic :-)
> > 
> > going by git log kernel/futex.c on a recent kernel the proposed patch
> > should indeed be followed by your patch, but I can't seem to find more
> > relevant patches.
> 
> Thanks a lot guys.  That is a dependency I'd never have come up with.
> 
> Willy -- this is probably of interest to you as well.   Hugh says that
> commit e6780f7243 ("futex: Fix uninterruptible loop due to gate_area")
> should be used if 9ea71503a8 ("futex: Fix regression with read only
> mappings") is used.  The v2.6.32.46 added 9ea71503a8 (as d64ec7bb),
> but I don't see a cherry pick of e6780f7243 in any v2.6.32.x yet.
> 
> Greg already applied it to 3.0.16 and 3.1.8 and it appeared in v3.2
> by default, so no other active stable releases need to worry.
> 
> I had to change page_mapping --> page, since the 2.6.34 baseline does
> not have a5b338f2b0b1ff73 ("thp: update futex compound knowledge")
> [added to v2.6.38] which introduces the shadow variable page_mapping.

Thank you very much Paul, I'm queuing it then. I hope to have some time for
a new -32 review soon, probably next week-end.

Cheers,
Willy