Re: [PATCH 1/3] revoke: misc fixes

[Nick Piggin]

Pekka Enberg wrote:
> On 3/16/07, Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
>
> > Also, a down_write_trylock attempt inside i_mmap_lock should be a valid
> > optimisation.
>
>
> I am not sure what you're thinking here. down_write_trylock acquires
> ->mmap_sem which can deadlock with ->i_mmap_lock, no?

You need hold and wait for a deadlock. So long as you don't block
(on mmap_sem) while holding i_mmap_lock, then you won't deadlock.

So you could just attempt a trylock, and if it works, then you
could revoke the vma right then and there. OTOH, the patch you
subsequently posted looks fine, so unless this is performance
critical then I wouldn't bother ;)

--
SUSE Labs, Novell Inc.
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