On Tue, Nov 23, 2021 at 09:28:34AM -0800, Shakeel Butt wrote: > On Tue, Nov 23, 2021 at 9:26 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > > > On 23.11.21 18:24, Shakeel Butt wrote: > > > On Tue, Nov 23, 2021 at 9:20 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > >> > > >> On 23.11.21 18:17, Shakeel Butt wrote: > > >>> On Tue, Nov 23, 2021 at 8:57 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > >>>> > > >>> [...] > > >>>>>> > > >>>>>> I do wonder which these locking contexts are exactly, and if we could > > >>>>>> also do the same thing on ordinary munmap -- because I assume it can be > > >>>>>> similarly problematic for some applications. > > >>>>> > > >>>>> This is a good question regarding munmap. One main difference is > > >>>>> munmap takes mmap_lock in write mode and usually performance critical > > >>>>> applications avoid such operations. > > >>>> > > >>>> Maybe we can extend it too most page zapping, if that makes things simpler. > > >>>> > > >>> > > >>> Do you mean doing sync THP split for most of page zapping functions > > >>> (but only if that makes things simpler)? > > >>> > > >> > > >> Yes -- if there are no downsides. > > >> > > > > > > I will try. At the moment the assumption of "Not null zap_details > > > implies leave swap entries" is giving me a headache. > > > > Not only you, did you stumble over > > > > https://lkml.kernel.org/r/20211115134951.85286-1-peterx@xxxxxxxxxx (thanks for raising this, David) > > > > already? > > > > Oh thanks for the pointer. I missed that. I will take a look. Thanks again. Hi, Shakeel, I saw your v2 has started to pass in zap_details, then we need know the side effect on that skip-swap-entry thing because with your v2 code munmap() will start to skip swap entry too (while it was not before). I saw that you didn't mention this in v2 patch either in commit message or code, not sure whether you digged that up. I think it needs some double check (or feel free to start this digging by reviewing my small patch above :). Thanks, -- Peter Xu
