On Sun, Sep 22, 2013 at 10:53:14AM +0200, Paolo Bonzini wrote: > Il 22/09/2013 09:42, Gleb Natapov ha scritto: > > On Mon, Sep 16, 2013 at 04:06:10PM +0200, Paolo Bonzini wrote: > >> Paul Gortmaker reported a BUG on preempt-rt kernels, due to taking the > >> mmu_lock within the raw kvm_lock in mmu_shrink_scan. He provided a > >> patch that shrunk the kvm_lock critical section so that the mmu_lock > >> critical section does not nest with it, but in the end there is no reason > >> for the vm_list to be protected by a raw spinlock. Only manipulations > >> of kvm_usage_count and the consequent hardware_enable/disable operations > >> are not preemptable. > >> > >> This small series thus splits the kvm_lock in the "raw" part and the > >> "non-raw" part. > >> > >> Paul, could you please provide your Tested-by? > >> > > Reviewed-by: Gleb Natapov <gleb@xxxxxxxxxx> > > > > But why should it go to stable? > > It is a regression from before the kvm_lock was made raw. Secondarily, It was made raw in 2.6.39 and commit message claims that it is done for -rt sake, why regression was noticed only now? > it takes a much longer time before a patch hits -rt trees (can even be > as much as a year) and this patch does nothing on non-rt trees. So > without putting it into stable it would get no actual coverage. > The change is not completely trivial, it splits lock. There is no obvious problem of course, otherwise you wouldn't send it and I would ack it :), but it does not mean that the chance for problem is zero, so why risk stability of stable even a little bit if the patch does not fix anything in stable? I do not know how -rt development goes and how it affects decisions for stable acceptance, why can't they carry the patch in their tree until they move to 3.12? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
