On Mon 02-07-18 14:24:29, Christian König wrote: > Am 02.07.2018 um 14:20 schrieb Michal Hocko: > > On Mon 02-07-18 14:13:42, Christian König wrote: > > > Am 02.07.2018 um 13:54 schrieb Michal Hocko: > > > > On Mon 02-07-18 11:14:58, Christian König wrote: > > > > > Am 27.06.2018 um 09:44 schrieb Michal Hocko: > > > > > > This is the v2 of RFC based on the feedback I've received so far. The > > > > > > code even compiles as a bonus ;) I haven't runtime tested it yet, mostly > > > > > > because I have no idea how. > > > > > > > > > > > > Any further feedback is highly appreciated of course. > > > > > That sounds like it should work and at least the amdgpu changes now look > > > > > good to me on first glance. > > > > > > > > > > Can you split that up further in the usual way? E.g. adding the blockable > > > > > flag in one patch and fixing all implementations of the MMU notifier in > > > > > follow up patches. > > > > But such a code would be broken, no? Ignoring the blockable state will > > > > simply lead to lockups until the fixup parts get applied. > > > Well to still be bisect-able you only need to get the interface change in > > > first with fixing the function signature of the implementations. > > That would only work if those functions return -AGAIN unconditionally. > > Otherwise they would pretend to not block while that would be obviously > > incorrect. This doesn't sound correct to me. > > > > > Then add all the new code to the implementations and last start to actually > > > use the new interface. > > > > > > That is a pattern we use regularly and I think it's good practice to do > > > this. > > But we do rely on the proper blockable handling. > > Yeah, but you could add the handling only after you have all the > implementations in place. Don't you? Yeah, but then I would be adding a code with no user. And I really prefer to no do so because then the code is harder to argue about. > > > > Is the split up really worth it? I was thinking about that but had hard > > > > times to end up with something that would be bisectable. Well, except > > > > for returning -EBUSY until all notifiers are implemented. Which I found > > > > confusing. > > > It at least makes reviewing changes much easier, cause as driver maintainer > > > I can concentrate on the stuff only related to me. > > > > > > Additional to that when you cause some unrelated side effect in a driver we > > > can much easier pinpoint the actual change later on when the patch is > > > smaller. > > > > > > > > This way I'm pretty sure Felix and I can give an rb on the amdgpu/amdkfd > > > > > changes. > > > > If you are worried to give r-b only for those then this can be done even > > > > for larger patches. Just make your Reviewd-by more specific > > > > R-b: name # For BLA BLA > > > Yeah, possible alternative but more work for me when I review it :) > > I definitely do not want to add more work to reviewers and I completely > > see how massive "flag days" like these are not popular but I really > > didn't find a reasonable way around that would be both correct and > > wouldn't add much more churn on the way. So if you really insist then I > > would really appreciate a hint on the way to achive the same without any > > above downsides. > > Well, I don't insist on this. It's just from my point of view that this > patch doesn't needs to be one patch, but could be split up. Well, if there are more people with the same concern I can try to do that. But if your only concern is to focus on your particular part then I guess it would be easier both for you and me to simply apply the patch and use git show $files_for_your_subystem on your end. I have put the patch to attempts/oom-vs-mmu-notifiers branch to my tree at git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git -- Michal Hocko SUSE Labs
