On Thu 04-10-18 13:17:52, David Rientjes wrote:
> On Wed, 26 Sep 2018, Kirill A. Shutemov wrote:
>
> > On Tue, Sep 25, 2018 at 02:03:26PM +0200, Michal Hocko wrote:
> > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > > index c3bc7e9c9a2a..c0bcede31930 100644
> > > --- a/mm/huge_memory.c
> > > +++ b/mm/huge_memory.c
> > > @@ -629,21 +629,40 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
> > > * available
> > > * never: never stall for any thp allocation
> > > */
> > > -static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
> > > +static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr)
> > > {
> > > const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
> > > + gfp_t this_node = 0;
> > > +
> > > +#ifdef CONFIG_NUMA
> > > + struct mempolicy *pol;
> > > + /*
> > > + * __GFP_THISNODE is used only when __GFP_DIRECT_RECLAIM is not
> > > + * specified, to express a general desire to stay on the current
> > > + * node for optimistic allocation attempts. If the defrag mode
> > > + * and/or madvise hint requires the direct reclaim then we prefer
> > > + * to fallback to other node rather than node reclaim because that
> > > + * can lead to excessive reclaim even though there is free memory
> > > + * on other nodes. We expect that NUMA preferences are specified
> > > + * by memory policies.
> > > + */
> > > + pol = get_vma_policy(vma, addr);
> > > + if (pol->mode != MPOL_BIND)
> > > + this_node = __GFP_THISNODE;
> > > + mpol_cond_put(pol);
> > > +#endif
> >
> > I'm not very good with NUMA policies. Could you explain in more details how
> > the code above is equivalent to the code below?
> >
>
> It breaks mbind() because new_page() is now using numa_node_id() to
> allocate migration targets for instead of using the mempolicy. I'm not
> sure that this patch was tested for mbind().
I am sorry but I do not follow, could you be more specific please?
MPOL_BIND should never get __GFP_THISNODE. What am I missing?
--
Michal Hocko
SUSE Labs
