Re: [PATCH 00/11] V4: rwsem changes + down_read_critical() proposal

[Michel Lespinasse]

On Tue, May 25, 2010 at 1:47 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> So what happened to those patches that dropped mmap_sem during I/O?

Yes, we do have patches trying to release the mmap_sem when a page
fault for a file backed VMA blocks on accessing the corresponding
file. We have not given up on these, and we intend to try submitting
them again. However, these patches do *not* address the case of a page
fault blocking while trying to get a free page (i.e. when you get
under high memory pressure).

> I really don't like people tinkering with the lock implementations like
> this. Nor do I like the naming, stats are in no way _critical_.

Critical here refers to the fact that you're not allowed to block
while holding the unfairly acquired rwsem.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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