On Wed, Oct 19, 2016 at 12:15:41PM +0100, Chris Wilson wrote: > On Tue, Oct 18, 2016 at 08:56:07AM +0200, Christoph Hellwig wrote: > > This is how everyone seems to already use them, but let's make that > > explicit. > > Ah, found an exception, vmapped stacks:
Oh, fun. So if we can't require vfree to be called from process context we also can't use a mutex to wait for the vmap flushing. Given that we free stacks from the scheduler context switch I also fear there is no good way to get a sleepable context there. The only other idea I had was to use vmap_area_lock for the protection that purge_lock currently provides, but that would require some serious refactoring to avoid recursive locking first.
