Date: Mon, 9 Aug 2004 17:47:01 -0400 From: Brian Fundakowski Feldman <green@FreeBSD.org> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/vm vm_kern.c vm_map.c vm_map.h Message-ID: <20040809214701.GE14657@green.homeunix.org> In-Reply-To: <20040809165215.A84463@grasshopper.cs.duke.edu> References: <200408091952.i79JqT4B076245@repoman.freebsd.org> <20040809165215.A84463@grasshopper.cs.duke.edu>
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On Mon, Aug 09, 2004 at 04:52:15PM -0400, Andrew Gallatin wrote: > Brian Feldman [green@FreeBSD.org] wrote: > > > * Require all mappings to be unwired before they are deleted. > > When VM space is still wired upon deletion, it will be waited > > upon for the following unwire. This makes vslock(9) work > > rather than allowing kernel-locked memory to be deleted > > out from underneath of its consumer as it would before. > > Can you explain in a little more detail what would happen now in the > following scenario: > > An application running in userspace allocates SIZE bytes at "addr", > either with an mmap or via sbrk. Then something in the kernel calls: > vm_map_wire(map, addr, addr + SIZE, TRUE) on its behalf. > Then the application frees (or munmaps) "addr". > > Does the application sleep waiting for something to unwire addr+SIZE? Yes, that is exactly what happens (replace TRUE with appropriate current flags); is there some other behavior you would expect to see? -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\
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