On Sat, Aug 19, 2017 at 07:54:20AM +1000, Benjamin Herrenschmidt wrote: > On Fri, 2017-08-18 at 10:04 -0700, Ram Pai wrote: > > Assume two threads of a task. > > > > T1: mprotect_key(foo, PAGE_SIZE, pkey=4); > > T1: set AMR to disable access for pkey 4; > > T1: key fault > > T2: set AMR to enable access to pkey 4; > > T1: fault handler called. > > This fault handler will see the new AMR and not the > > one at the time of the fault. > > You aren't context switching AMR with the threads ? Ugh... something is > very wrong then.
I do store and restore AMR accross context switch. So nevermind; the above problem cannot happen. RP
