On Sun 30-04-17 16:33:10, Cristopher Lameter wrote: > On Wed, 26 Apr 2017, Vlastimil Babka wrote: > > > > Such an application typically already has such logic and executes a > > > binding after discovering its numa node configuration on startup. It would > > > have to be modified to redo that action when it gets some sort of a signal > > > from the script telling it that the node config would be changed. > > > > > > Having this logic in the application instead of the kernel avoids all the > > > kernel messes that we keep on trying to deal with and IMHO is much > > > cleaner. > > > > That would be much simpler for us indeed. But we still IMHO can't > > abruptly start denying page fault allocations for existing applications > > that don't have the necessary awareness. > > We certainly can do that. The failure of the page faults are due to the > admin trying to move an application that is not aware of this and is using > mempols. That could be an error. Trying to move an application that > contains both absolute and relative node numbers is definitely something > that is potentiall so screwed up that the kernel should not muck around > with such an app. > > Also user space can determine if the application is using memory policies > and can then take appropriate measures (message to the sysadmin to eval > tge situation f.e.) or mess aroud with the processes memory policies on > its own. > > So this is certainly a way out of this mess. So how are you going to distinguish VM_FAULT_OOM from an empty mempolicy case in a raceless way? -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
