On Fri, 2007-09-21 at 12:21 -0700, Linus Torvalds wrote: > Yeah, and the whole thing seems totally bogus. It totally depends on > mmu_gather doing everything right (which very much includes the dependency > on mmu gathering disabling preempt). > > For exmaple, if we were to go back to the original small tlb_gather with a > simple quicklist on the stack, rather than the per-cpu datastructure, the > quicklists would immediately break horribly - simply because they are > incorrectly now depending on the internal semantics of that tlb-gather. > > As it is, the quicklists try to be something separate, but by virtue of > being separate, they will always be buggy. > > The only way to fix it would be to integrate the quicklist stuff *with* > the mmu_gather stuff, so that these kinds of implementation issues are > explicitly shown in the relationship, instead of havign two "independent" > pieces of code where one piece very subtly depends on the exact > implementation of the other.
I've been mostly offline since KS (since a bit before in fact), so I missed some of those discussions but so that you know, I'm toying a bit with mmu gather and page table accessors at the moment, and one of the things I've been contemplating is just that ... integrating a quicklist in the gather to handle just that (and possibly other issues that have been overlooked on some archs). I'd suggest just reverting the patch for now (well, I see from the commit list that you did just that) and I'll try to come up with something better. Christoph, I'd be happy if you didn't start butchering mmu_gather just right now since I'm doing just that and it will collide all over the place :-) Or if you want something specific done, please throw ideas/patches at me and I'll integrate that in my serie. Cheers, Ben. - 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/
