Michal Hocko wrote: > I have checked the vnet code and it doesn't seem to rely on > copy_from_user/get_user AFAICS. Other users of use_mm() need to copy to > the userspace only as well. So we should be perfectly safe to OOM reap > address space even when it is shared by the kthread [1] so this is > not really needed for the OOM correctness purpose. It would be much > nicer if the kthread didn't pin the mm for two long outside of the OOM > handling as well of course but that lowers the priority of the change. > > [1] http://lkml.kernel.org/r/20160613112348.GC6518@xxxxxxxxxxxxxx It seems to me that vhost code relies on copy from the userspace. use_mm(dev->mm) and unuse_mm(dev->mm) are used inside vhost_worker(). work->fn(work) is initialized by vhost_work_init(). vhost_scsi_open() passes vhost_scsi_complete_cmd_work() and vhost_scsi_evt_work() as ->fn, and both functions call __get_user(). vhost_scsi_complete_cmd_work() { vhost_signal() { vhost_notify() { __get_user() } } } vhost_scsi_evt_work() { vhost_scsi_do_evt_work() { vhost_get_vq_desc() { __get_user() / __copy_from_user() get_indirect() { copy_from_iter() } } } } -- 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>