Messages in this thread | | | Subject | Re: [RFC] page fault retry with NOPAGE_RETRY | From | Benjamin Herrenschmidt <> | Date | Sat, 16 Sep 2006 11:03:00 +1000 |
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On Fri, 2006-09-15 at 14:30 +0100, Hugh Dickins wrote: > On Fri, 15 Sep 2006, Andrew Morton wrote: > > > > This assumes that no other heavyweight process will try to modify this > > single-threaded process's mm. I don't _think_ that happens anywhere, does > > it? access_process_vm() is the only case I can think of, > > "Modify" in the sense of fault into. > Yes, access_process_vm() is all I can think of too. > > > and it does down_read(other process's mmap_sem). > > If there were anything else, it'd have to do so too (if not down_write). > > I too like NOPAGE_RETRY: as you've both observed, it can help to solve > several different problems.
Yes, I don't need any of the safeguards that Andrew mentioned in my case though. I want to return all the way to userland because I want signals to be handled (which might also be a good thing in your case in fact, so that a process being starved by that new mecanism can still be interrupted).
I would ask that if you decide that the more complex approach is not 2.6.19 material, that the simple addition of NOPAGE_RETRY as I've defined could be included in a first step so I can solve my problem (and possibly other drivers wanting to do funky things with no_page() and still take signals), and the google patch be rebased on top of that for additional simmering :)
Cheers, Ben.
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