Andrew Morton wrote:
This is because there is no file descriptor or anything else associated with the pages which permits the kernel to clean stuff up on unclean application exit. Also there are the obvious issues with permitting pinning of unbounded amounts of memory.
Then that might explain the "bug" that we're seeing with get_user_pages(). We've been assuming that get_user_pages() mappings are permanent.
Well, I was just about to re-implement get_user_pages() support in our driver to demonstrate the bug. I guess I'll hold off on that.
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 use.
-- Timur Tabi Staff Software Engineer [email protected] 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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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