On Mon, Jan 11, 2021 at 11:25:37AM -0800, Linus Torvalds wrote: > On Mon, Jan 11, 2021 at 6:24 AM Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote: > > > > I wonder if it would be acceptable to pass down to faultaround a copy > > of vmf, so it mess with it without risking to corrupt the original one? > > I'd almost prefer to split vmf into two parts: the 'this is the fault > info' part and the 'this is the fault handling state' part. > > So the first one would be filled in by the actual page faulter (or > GUP) - and then be 'const' during the lookup, while the second one > would be set up by handle_mm_fault() and would contain that "this is > the current state of my fault state machine" and contain things like > that ->pte thing. > > And then if somebody actually needs to pass in "modified fault state" > (ie that whole "I'm doing fault-around, so I'll use multiple > addresses") they'd never modify the address in the fault info, they'd > just pass the address as an explicit argument (like most cases already > do - the "change addr or flags in vmf" is actually already _fairly_ > rare). Alright then, I'll take another crack at this for v3 and see how far I get. Will
