Re: [PATCH] mmu notifiers #v6

Robin Holt
2008-02-20T14:42:14Z

On Wed, Feb 20, 2008 at 11:39:42AM +0100, Andrea Arcangeli wrote:
> XPMEM simply can't use RCU for the registration locking if it wants to
> schedule inside the mmu notifier calls. So I guess it's better to add

Whoa there. In Christoph's patch, we did not use rcu for the list. It
was a simple hlist_head. The list manipulations were done under
down_write(&current->mm->mmap_sem) and would therefore not be racy. All
the callout locations are already acquiring the mmap_sem at least
readably, so we should be safe. Maybe I missed a race somewhere.

Thanks,
Robin