> > > And it doesn't sound too hard to solve: when current algorithm doesn't > > > seem to be making progress, then it will have to be done the hard way, > > > searching for for all nonlinear ptes of a page to unmap. > > > > Ah, you see, but that is when you've already lost. > > > > The DoS is about the computational complexity of the reclaim, not if it > > will ever come out of it with free pages. > > If we really want to, we could limit it to mlock for !root. This is > a reasonable way to solve the problem, and UML could fall back on > vma emulated version if they didn't want to use mlock memory... > > Or we could limit the size/number of nonlinear vmas that could be > created. > > But just quietly, I think there are probably a lot of other ways to > perform a local DoS anyway ;)
I aggree, requiring apps to mlock would probably just make things slightly worse for about 100% of users, without any gain. There could be a /proc/sys/vm/turn_off_nonlinear_for_paranoid_sysadmin knob that would unconditionally emulate nonlinear vmas. Miklos - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
