On Wednesday, 15 September 2021 12:52:48 PM AEST Peter Xu wrote: > > > The flag introduced in this patch will be a preparation for more bits defined > > > in the future, e.g., for a new bit in flag to show whether to persist the > > > upcoming uffd-wp bit in pgtable entries. > > > > That's kind of the problem. The patch itself looks correct to me however as > > mentioned it is mostly reverting a previous cleanup and it's hard to tell why > > that's justified without the subsequent patches. Perhaps it makes the usage of > > zap_details a bit clearer, but a comment also would with less code. > > > > I know you want to try and shrink the uffd-wp series but I think this patch > > might be easier to review if it was included as part of that series. > > I posted it because I think it's suitable to have it even without uffd-wp. > > I tried to explain it above on two things this patch wanted to fix: > > Firstly the comment is wrong; we've moved back and forth on changing the > zap_details flags but the comment is not changing along the way and it's not > matching the code right now. > > Secondly I do think we should have a flag showing explicit willingness to skip > swap entries. Yes, uffd-wp is the planned new one, but my point is anyone who > will introduce a new user of zap_details pointer could overlook this fact. The > new flag helps us to make sure someone will at least read the flags and know > what'll happen with it. > > For the 2nd reasoning, I also explicitly CCed Kirill too, so Kirill can provide > any comment if he disagrees. For now, I still think we should keep having such > a flag otherwise it could be error-prone. > > Could you buy-in above reasoning? Kind of, I do think it makes the usage of details a bit clearer or at least harder to miss. It is just that if that was the sole aim of this patch I think there might be simpler (less code) ways of doing so. > Basically above is what I wanted to express in my commit message. I hope that > can justify that this patch (even if extremly simple) can still be considered > as acceptable upstream even without uffd-wp series. > > If you still insist on this patch not suitable for standalone merging and > especially if some other reviewer would think the same, I can move it back to > uffd-wp series for sure. Then I'll repost this series with 4 patches only. I won't insist, the code looks correct and it doesn't make things any less clear so you can put my Reviewed-by on it and perhaps leave it to Andrew or another reviewer to determine if this should be taken in this series or as part of a future uffd-wp series. - Alistair > In all cases, thanks for looking at the series. > >
