On Thu 07-04-16 15:45:02, Frank Mehnert wrote: > On Wednesday 06 April 2016 17:33:43 Michal Hocko wrote: [...] > > Do you map your pages to the userspace? If yes then vma with VM_IO or > > VM_PFNMAP should keep any attempt away from those pages. > > Yes, such memory objects are also mapped to userland. Do you think that > VM_IO or VM_PFNMAP would guard against NUMA page migration? Both auto numa and manual numa migration checks vma_migratable and that excludes both VM flags. > Because when > NUMA page migration was introduced (I believe with Linux 3.8) I tested > both flags and saw that they didn't prevent the migration on such VM > areas. Maybe this changed in the meantime, do you have more information > about that? I haven't checked the history much but vma_migratable should be there for quite some time. Maybe it wasn't used in the past. Dunno > The drawback of at least VM_IO is that such memory is not part of a core > dump. that seems to be correct as per vma_dump_size > Actually currently we use vm_insert_page() for userland mapping > and mark the VM areas as > > VM_DONTEXPAND | VM_DONTDUMP but that means that it won't end up in the dump either. Or am I missing your point. -- Michal Hocko SUSE Labs -- 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>