On Thu, 15 Jun 2017 10:07:39 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote: > On Wed 14-06-17 12:26:46, Dan Williams wrote: > > On Wed, Jun 14, 2017 at 5:45 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > On Tue 13-06-17 16:08:26, Dan Williams wrote: > > >> Turn the macro into a static inline and rewrite the condition checks for > > >> better readability in preparation for adding another condition. > > >> > > >> Cc: Jan Kara <jack@xxxxxxx> > > >> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > >> Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > > >> [ross: fix logic to make conversion equivalent] > > >> Acked-by: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > > >> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > > > > > > This is really a nice deobfuscation! Please note this will conflict with > > > http://lkml.kernel.org/r/1496415802-30944-1-git-send-email-rppt@xxxxxxxxxxxxxxxxxx > > > > > > > > > Trivial to resolve but I thought I should give you a heads up. > > > > Hmm, I'm assuming that vma_is_dax() should override PRCTL_THP_DISABLE? > > ...and while we're there should vma_is_dax() also override > > VM_NOHUGEPAGE? This is with the assumption that the reason to turn off > > huge pages is to avoid mm pressure, dax exerts no such pressure. > > As the changelog of the referenced patch says another reason is to stop > khugepaged from interfering and collapsing smaller pages into THP. If > DAX mappings are subject to khugepaged then we really need to exclude > it. Why would you want to override user's decision to disable THP > anyway? I can see why the global knob should be ignored but if the > disable is targeted for the specific VMA or the process then we should > obey that, no? So... Like this? static inline bool transparent_hugepage_enabled(struct vm_area_struct *vma) { if (vma->vm_flags & VM_NOHUGEPAGE)) return false; if (is_vma_temporary_stack(vma)) return false; if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) return false; if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG)) return true; if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)) return !!(vma->vm_flags & VM_HUGEPAGE); return false; } -- 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>
