On Thu 27-10-22 14:47:22, Huang, Ying wrote: > Michal Hocko <mhocko@xxxxxxxx> writes: [...] > > I can imagine workloads which wouldn't like to get their memory demoted > > for some reason but wouldn't it be more practical to tell that > > explicitly (e.g. via prctl) rather than configuring cpusets/memory > > policies explicitly? > > If my understanding were correct, prctl() configures the process or > thread. Not necessarily. There are properties which are per adddress space like PR_[GS]ET_THP_DISABLE. This could be very similar. > How can we get process/thread configuration at demotion time? As already pointed out in previous emails. You could hook into folio_check_references path, more specifically folio_referenced_one where you have all that you need already - all vmas mapping the page and then it is trivial to get the corresponding vm_mm. If at least one of them has the flag set then the demotion is not allowed (essentially the same model as VM_LOCKED). -- Michal Hocko SUSE Labs
