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Date: Fri, 21 Sep 2007 12:26:22 -0700 (PDT) From: Christoph Lameter <clameter@....com> To: Linus Torvalds <torvalds@...ux-foundation.org> cc: "Siddha, Suresh B" <suresh.b.siddha@...el.com>, akpm@...ux-foundation.org, ak@...e.de, linux-kernel@...r.kernel.org, tony.luck@...el.com, asit.k.mallick@...el.com Subject: Re: x86_64: potential critical issue with quicklists and page table pages On Fri, 21 Sep 2007, 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). The quicklists have been existing for a long time in this relationship and were actually developed initially (by Dave Miller I believe) to work this way. The generic TLB flushing thing may have developed in parallel on other platforms that did not use quicklists. > 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. Hmmmm.. Right the integration of the approaches that have now diverged on various platforms could be better. > As it is, the quicklists try to be something separate, but by virtue of > being separate, they will always be buggy. I guess we need to re-join what was separated by developments on different platforms. > 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. Right. But will that not mean that quicklists would have to be used on all platforms in a generic way? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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