On Tue, Mar 16, 2021 at 11:03:05AM -0700, Davidlohr Bueso wrote: > On Tue, 16 Mar 2021, Peter Zijlstra wrote: > > > > IIRC we made the explicit choice to never loop here. That saves having > > to worry about getting stuck in in-kernel loops. > > > > Userspace triggering the case where the futex goes corrupt is UB, after > > that we have no obligation for anything to still work. It's on them, > > they get to deal with the bits remaining. > > I was kind of expecting this answer, honestly. After all, we are warned > about violations to the 10th: > > * [10] There is no transient state which leaves owner and user space > * TID out of sync. Except one error case where the kernel is denied > * write access to the user address, see fixup_pi_state_owner(). > > (btw, should we actually WARN_ON_ONCE this case such that the user is > well aware things are screwed up?)
I'm not sure WARN is appropriate, it is something unpriv userspace can trigger at will.
