Messages in this thread | | | Subject | Re: [PATCH][RFC] fix kernel BUG at mm/migrate.c:719! in 2.6.26-rc5-mm3 | From | Lee Schermerhorn <> | Date | Tue, 17 Jun 2008 15:28:42 -0400 |
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On Tue, 2008-06-17 at 19:33 +0100, Hugh Dickins wrote: > On Tue, 17 Jun 2008, Lee Schermerhorn wrote: > > > > Now I wonder if the assertion that newpage count == 1 could be violated? > > I don't see how. We've just allocated and filled it and haven't > > unlocked it yet, so we should hold the only reference. Do you agree? > > Disagree: IIRC, excellent example of the kind of assumption > that becomes invalid with Nick's speculative page references. > > Someone interested in the previous use of the page may have > incremented the refcount, and in due course will find that > it's got reused for something else, and will then back off. >
Yeah. Kosaki-san mentioned that we'd need some rework for the speculative page cache work. Looks like we'll need to drop the VM_BUG_ON().
I need to go read up on the new invariants we can trust with the speculative page cache.
Thanks, Lee
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