Re: [PATCH/RFC] Futex mmap_sem deadlock

Benjamin Herrenschmidt
2005-02-22T21:20:20Z

On Wed, 2005-02-23 at 08:16 +1100, Benjamin Herrenschmidt wrote:
> On Tue, 2005-02-22 at 11:36 -0800, Linus Torvalds wrote:
>
> > DavidH - what's the word on nested read-semaphores like this? Are they
> > supposed to work (like nested read-spinlocks), or do we need to do the
> > things Olof does?
>
> Isn't Olof scheme racy ? Can't the stuff get swapped out between the
> first get_user() and the "real" one ?

Forget it, I missed the check_user_page_readable() guy within the
semaphore protection. I didn't know that function ;)

Ben.