Re: [PATCH/RFC] Futex mmap_sem deadlock

[Olof Johansson]

On Tue, Feb 22, 2005 at 09:07:52PM +0000, Jamie Lokier wrote:
> 
> That won't work because the vma lock must be help between key
> calculation and get_user() - otherwise futex is not reliable.  It
> would work if the futex key calculation was inside the loop.

Sure, but that's still true: It's just that the get_user() is done twice
instead. The semaphore is never released between the key calculation and
the "real" get_user().

> A much simpler solution (and sorry for not offering it earlier,
> because Andrew Morton pointed out this bug long ago, but I was busy), is:

Either way works for me. Andrew/Linus, got a preference? I'll either
post my refresh based on Andrews comments, or code up Jamie's
suggestion.


-Olof
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/