Re: [PATCH] Alternate futex non-page-pinning and COW fix

[Rusty Russell]

In message <Pine.LNX.4.44.0309031141310.1273-100000@xxxxxxxxxxxxxxxxxxxxx> you write:
> On Wed, 3 Sep 2003, Jamie Lokier wrote:
> > I have an obvious fix for mremap(): rehash all the futexes in its
> > range.  That's not in the attached patch, but it will be in the next one.
> 
> Will it be worth the code added to handle it?  I wonder the same of
> non-linear (sys_mremap and sys_remap_file_pages, familiar troublemakers).
> But all credit for handling them, good to reduce "undefined behaviour"s.

I don't have a problem with the omission.  mremap is logically
equivalent to munmap + mmap, so it's a subset of the "I unmapped
underneath my futex!".  It's not like it's going to happen without the
caller knowing: if the address doesn't change, then the futexes won't
break.  If they do, the caller needs to reset them anyway.

Cheers,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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