On Mon, Aug 22, 2022 at 04:56:47PM +0000, Song Liu wrote: > > > > On Aug 22, 2022, at 9:34 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > On Mon, Aug 22, 2022 at 03:46:38PM +0000, Song Liu wrote: > >> Could you please share your feedback on this? > > > > I've looked at it all of 5 minutes, so perhaps I've missed something. > > > > However, I'm a little surprised you went with a second tree instead of > > doing the top-down thing for data. The way you did it makes it hard to > > have guard pages between text and data. > > I didn't realize the importance of the guard pages. But it is not too I'm not sure how important it is, just seems like a good idea to trap anybody trying to cross that divide. Also, to me it seems like a good idea to have a single large contiguous text region instead of splintered 2M pages. > hard to do it with this approach. For each 2MB text page, we can reserve > 4kB on the beginning and end of it. Would this work? Typically a guard page has different protections (as in none what so ever) so that every access goes *splat*.
