On Wed, Jan 30, 2008 at 02:37:20PM +0100, Andrea Arcangeli wrote: > On Tue, Jan 29, 2008 at 06:28:05PM -0600, Jack Steiner wrote: > > On Tue, Jan 29, 2008 at 04:20:50PM -0800, Christoph Lameter wrote: > > > On Wed, 30 Jan 2008, Andrea Arcangeli wrote: > > > > > > > > invalidate_range after populate allows access to memory for which > > > > > ptes > > > > > were zapped and the refcount was released. > > > > > > > > The last refcount is released by the invalidate_range itself. > > > > > > That is true for your implementation and to address Robin's issues. Jack: > > > Is that true for the GRU? > > > > I'm not sure I understand the question. The GRU never (currently) takes > > a reference on a page. It has no mechanism for tracking pages that > > were exported to the external TLBs. > > If you don't have a pin, then things like invalidate_range in > remap_file_pages can't be safe as writes through the external TLBs can > keep going on pages in the freelist. For you to be safe w/o a > page-pin, you need to return in the direction of invalidate_page > inside ptep_clear_flush (or anyway before > page_cache_release/__free_page/put_page...). You're generally not safe > with any invalidate_range that may run after the page pointed by the > pte has been freed (or can be freed by the VM anytime because of being > unpinned cache).
Yuck.... I see what you mean. I need to review to mail to see why this changed but in the original discussions with Christoph, the invalidate_range callouts were suppose to be made BEFORE the pages were put on the freelist. --- jack -- 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/