Re: locking question: do_mmap(), do_munmap()

[Manfred Spraul <manfreds@colorfullife.com>]

Alexander Viro wrote:
> Moreover, sys_uselib() may do
> interesting things to cloned processes. IMO the right thing would be to
> check for the number of mm users.

I don't know the details of the mm implementation, but if there is only
one user, then down(&mm->mmap_sem) will never sleep, and you loose
nothing by getting the semaphore.

I would prefer a clean implementation, ie always down() before
do_mmap(), and ASSERT_DOWN() macros to enforce this.

--
	Manfred
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