Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation

From: Timur Tabi
Date: Mon Apr 25 2005 - 18:25:09 EST

Andrew Morton wrote:

They are permanent until someone runs put_page() against all the pages. What I'm saying is that all current callers of get_user_pages() _do_ run
put_page() within the same syscall or upon I/O termination.

Oh, okay then. I guess I'll get back to work!

Actually, with RDMA, "I/O termination" technically doesn't happen until the memory is deregistered. When the memory is registered, all that means is that it's should be pinned and the virtual-to-physical should be stored. No actual I/O occurs at that point.

If you look at the Infiniband code that was recently submitted, I think you'll see it does exactly that: after calling mlock(), the driver calls get_user_pages(), and it stores the page mappings for future

I was talking about the code that Roland mentioned in the first message of this thread - the user-space verbs support. He said the code calls mlock() and get_user_pages().

FYI, our driver detects the process termination and cleans up everything itself.

Timur Tabi
Staff Software Engineer

One thing a Southern boy will never say is,
"I don't think duct tape will fix it."
-- Ed Smylie, NASA engineer for Apollo 13
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