This is probably more appropriate to be directed at the linux-mm mailing list. On Tue, Jun 04, 2013 at 09:22:10AM +0200, Frank Mehnert wrote: > Hi, > > our memory management on Linux hosts conflicts with NUMA page migration. > I assume this problem existed for a longer time but Linux 3.8 introduced > automatic NUMA page balancing which makes the problem visible on > multi-node hosts leading to kernel oopses. > > NUMA page migration means that the physical address of a page changes. > This is fatal if the application assumes that this never happens for > that page as it was supposed to be pinned. > > We have two kind of pinned memory: > > A) 1. allocate memory in userland with mmap() > 2. madvise(MADV_DONTFORK) > 3. pin with get_user_pages(). > 4. flush dcache_page() > 5. vm_flags |= (VM_DONTCOPY | VM_LOCKED) > (resulting flags are VM_MIXEDMAP | VM_DONTDUMP | VM_DONTEXPAND | > VM_DONTCOPY | VM_LOCKED | 0xff) I don't think this type of allocation should be affected. The get_user_pages() call should elevate the pages reference count which should prevent migration from completing. I would, however, wait for a more definitive answer. > B) 1. allocate memory with alloc_pages() > 2. SetPageReserved() > 3. vm_mmap() to allocate a userspace mapping > 4. vm_insert_page() > 5. vm_flags |= (VM_DONTEXPAND | VM_DONTDUMP) > (resulting flags are VM_MIXEDMAP | VM_DONTDUMP | VM_DONTEXPAND | 0xff) > > At least the memory allocated like B) is affected by automatic NUMA page > migration. I'm not sure about A). > > 1. How can I prevent automatic NUMA page migration on this memory? > 2. Can NUMA page migration also be handled on such kind of memory without > preventing migration? > > Thanks, > > Frank > -- > Dr.-Ing. Frank Mehnert | Software Development Director, VirtualBox > ORACLE Deutschland B.V. & Co. KG | Werkstr. 24 | 71384 Weinstadt, Germany > > Hauptverwaltung: Riesstr. 25, D-80992 München > Registergericht: Amtsgericht München, HRA 95603 > Geschäftsführer: Jürgen Kunz > > Komplementärin: ORACLE Deutschland Verwaltung B.V. > Hertogswetering 163/167, 3543 AS Utrecht, Niederlande > Handelsregister der Handelskammer Midden-Niederlande, Nr. 30143697 > Geschäftsführer: Alexander van der Ven, Astrid Kepper, Val Maher > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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>