On Wed 27-06-18 08:57:18, Jason Gunthorpe wrote: > On Wed, Jun 27, 2018 at 02:42:55PM +0200, Jan Kara wrote: > > On Wed 27-06-18 13:59:27, Michal Hocko wrote: > > > On Wed 27-06-18 13:53:49, Jan Kara wrote: > > > > On Wed 27-06-18 13:32:21, Michal Hocko wrote: > > > [...] > > > > > Appart from that, do we really care about 32b here? Big DIO, IB users > > > > > seem to be 64b only AFAIU. > > > > > > > > IMO it is a bad habit to leave unpriviledged-user-triggerable oops in the > > > > kernel even for uncommon platforms... > > > > > > Absolutely agreed! I didn't mean to keep the blow up for 32b. I just > > > wanted to say that we can stay with a simple solution for 32b. I thought > > > the g-u-p-longterm has plugged the most obvious breakage already. But > > > maybe I just misunderstood. > > > > Most yes, but if you try hard enough, you can still trigger the oops e.g. > > with appropriately set up direct IO when racing with writeback / reclaim. > > gup longterm is only different from normal gup if you have DAX and few > people do, which really means it doesn't help at all.. AFAIK?? Right, what I wrote works only for DAX. For non-DAX situation g-u-p longterm does not currently help at all. Sorry for confusion. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
