Re: [PATCH v4 15/20] powerpc/mm: Avoid useless lock with single page fragments

[Christophe LEROY]

Le 19/09/2018 Ã 04:56, Aneesh Kumar K.V a ÃcritÂ:
> On 9/18/18 10:27 PM, Christophe Leroy wrote:
> > There is no point in taking the page table lock as
> > pte_frag is always NULL when we have only one fragment.
> >
> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> > ---
> > Â arch/powerpc/mm/pgtable-frag.c | 3 +++
> > Â 1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/powerpc/mm/pgtable-frag.c 
> > b/arch/powerpc/mm/pgtable-frag.c
> > index bc924822dcd6..ab4910e92aaf 100644
> > --- a/arch/powerpc/mm/pgtable-frag.c
> > +++ b/arch/powerpc/mm/pgtable-frag.c
> > @@ -85,6 +85,9 @@ static pte_t *get_pte_from_cache(struct mm_struct *mm)
> > Â {
> > ÂÂÂÂÂ void *pte_frag, *ret;
> >
> > +ÂÂÂ if (PTE_FRAG_NR == 1)
> > +ÂÂÂÂÂÂÂ return NULL;
> > +
> > ÂÂÂÂÂ spin_lock(&mm->page_table_lock);
> > ÂÂÂÂÂ ret = mm->context.pte_frag;
> > ÂÂÂÂÂ if (ret) {
>
> May be update get_pmd_from_cache too?

Ok, done in v5

Christophe