[ofa-general] Re: [PATCH 08 of 11] anon-vma-rwsem

[Benjamin Herrenschmidt]

On Thu, 2008-05-08 at 00:44 +0200, Andrea Arcangeli wrote:
> 
> Please note, we can't allow a thread to be in the middle of
> zap_page_range while mmu_notifier_register runs.

You said yourself that mmu_notifier_register can be as slow as you
want ... what about you use stop_machine for it ? I'm not even joking
here :-)

> vmtruncate takes 1 single lock, the i_mmap_lock of the inode. Not more
> than one lock and we've to still take the global-system-wide lock
> _before_ this single i_mmap_lock and no other lock at all.

Ben.