On Thu, Feb 2, 2023 at 12:04 PM Peter Xu <peterx@xxxxxxxxxx> wrote: > > On Wed, Feb 01, 2023 at 03:57:33PM -0800, Yang Shi wrote: > > > There's another problem where the current vma may not have uffd armed, > > > khugepaged may think it has nothing to do with uffd and moved on with > > > collapsing, but actually it's armed in another vma of either the current mm > > > or just another mm's. > > > > Out of curiosity, could you please elaborate how another vma armed > > with userfaultfd could have an impact on the vmas that are not armed? > > It's e.g. when >1 vmas mapped to the same shmem file on the same range, one > registered with uffd missing, others not. Then others can cause page cache > populated without generating message to the vma that got uffd missing mode > registered, so there'll be the same issue as when khugepaged accidentally > does thp collapsings. Thanks, Got it, thank you. > > -- > Peter Xu >
