From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH 3/4] Swapping Date: Sun, 14 Oct 2007 12:11:23 -0500 Message-ID: <47124DBB.9030708@codemonkey.ws> References: <47102919.6070802@qumranet.com> <471124D4.3090901@codemonkey.ws> <471126D9.4030204@qumranet.com> <47112D66.4020500@qumranet.com> <47115207.3090909@codemonkey.ws> <4711542F.2060306@qumranet.com> <4711563D.8020000@codemonkey.ws> <4711B101.7070305@qumranet.com> <47122E57.7060308@codemonkey.ws> <47123EFA.1010808@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Avi Kivity Return-path: In-Reply-To: <47123EFA.1010808-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Avi Kivity wrote: > Anthony Liguori wrote: >> Avi Kivity wrote: >>> Anthony Liguori wrote: >>> >>>> I think it's just a matter of calling do_mmap() with the >>>> appropriate parameters. It looks likes there's some drivers call >>>> do_mmap() directly. >>>> >>>> >>> >>> This will halve the maximum size of virtual machines on i386 since >>> userspace will also mmap() the memory, and the virtual address space is >>> restricted to 3GB. >>> >> >> I wonder if there is a way to force the mmap() to return the >> userspace address we previously allocated. >> > > Yes: > >> >> unsigned long >> get_unmapped_area(struct file *file, unsigned long addr, unsigned >> long len, >> unsigned long pgoff, unsigned long flags) >> { >> unsigned long (*get_area)(struct file *, unsigned long, >> unsigned long, unsigned long, >> unsigned long); >> >> get_area = current->mm->get_unmapped_area; >> if (file && file->f_op && file->f_op->get_unmapped_area) >> get_area = file->f_op->get_unmapped_area; >> addr = get_area(file, addr, len, pgoff, flags); Hrm, so you can return the area that should be used but you still install vma_ops? Wouldn't that result in an infinite loop when userspace attempted to map the area since we'll try to satisfy the nopage handler by doing a get_user_pages? Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/