On Tue, Jul 14, 2015 at 9:11 PM, Christoph Lameter <cl@xxxxxxxxx> wrote: > On Tue, 14 Jul 2015, Konstantin Khlebnikov wrote: > >> Enabling debug in runtime breaks creation of new kmem caches: >> they have incompatible flags thus cannot be merged but unique >> names are taken by existing caches. > > What breaks? The same commands from first patch: # echo 1 | tee /sys/kernel/slab/*/sanity_checks # modprobe configfs loading configfs now fails (without crashing kernel though) because of "sysfs: cannot create duplicate filename '/kernel/slab/:t-0000096'" Of course we could rename sysfs entry when enable debug options but that requires much more code than my "stop merging" solution. > > Caches may already have been merged and thus the question is what to do > about a cache that has multiple aliases if a runtime option is requested. > The solution that slub implements is to only allow a limited number of > debug operations to be enabled. Those then will appear to affect all > aliases of course. > > Creating additional caches later may create additional > aliasing which will then restrict what options can be changed. > > Other operations are also restricted depending on the number of objects > stored in a cache. A cache with zero objects can be easily reconfigured. > If there are objects then modifications that impact object size are not > allowed anymore. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>