On 05/24/2017 12:39 PM, Mike Rapoport wrote: >> Hm so the prctl does: >> >> if (arg2) >> me->mm->def_flags |= VM_NOHUGEPAGE; >> else >> me->mm->def_flags &= ~VM_NOHUGEPAGE; >> >> That's rather lazy implementation IMHO. Could we change it so the flag >> is stored elsewhere in the mm, and the code that decides to (not) use >> THP will check both the per-vma flag and the per-mm flag? > > I afraid I don't understand how that can help. > What we need is an ability to temporarily disable collapse of the pages in > VMAs that do not have VM_*HUGEPAGE flags set and that after we re-enable > THP, the vma->vm_flags for those VMAs will remain intact. That's what I'm saying - instead of implementing the prctl flag via mm->def_flags (which gets permanently propagated to newly created vma's but e.g. doesn't affect already existing ones), it would be setting a flag somewhere in mm, which khugepaged (and page faults) would check in addition to the per-vma flags. > -- > Sincerely yours, > Mike. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
