On Sun, Dec 16, 2012 at 7:29 PM, Michel Lespinasse <walken@xxxxxxxxxx> wrote: > On Sun, Dec 16, 2012 at 10:05 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >> On Sun, Dec 16, 2012 at 4:39 AM, Michel Lespinasse <walken@xxxxxxxxxx> wrote: >>> I think this could be done by extending the mlock work I did as part >>> of v2.6.38-rc1. The commit message for >>> c explains the idea; basically >>> mlock() was split into do_mlock() which just sets the VM_LOCKED flag >>> on vmas as needed, and do_mlock_pages() which goes through a range of >>> addresses and actually populates/mlocks each individual page that is >>> part of a VM_LOCKED vma. >> >> Doesn't this have the same problem? It holds mmap_sem for read for a >> long time, and if another writer comes in then r/w starvation >> prevention will kick in. > > Well, my point is that do_mlock_pages() doesn't need to hold the > mmap_sem read side for a long time. It currently releases it when > faulting a page requires a disk read, and could conceptually release > it more often if needed. I can't find this code. It looks like do_mlock_pages calls __mlock_vma_pages_range, which calls __get_user_pages, which makes its way to __do_fault, which doesn't seem to drop mmap_sem. --Andy -- 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>