Re: [PATCH v3 2/2] LoongArch: update local TLB if PTE entry exists

[Qi Zheng]

On 2022/9/29 19:42, Huacai Chen wrote:
> Hi, all,
>
> Should this patch go via mm tree or loongarch tree? If via mm tree, then

Both are fine for me. Hi Andrew, can you help to apply this patch
series?

> Acked-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>

Thanks. :)

> On Thu, Sep 29, 2022 at 7:23 PM Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
> > Currently, the implementation of update_mmu_tlb() is empty if
> > __HAVE_ARCH_UPDATE_MMU_TLB is not defined. Then if two threads
> > concurrently fault at the same page, the second thread that did
> > not win the race will give up and do nothing. In the LoongArch
> > architecture, this second thread will trigger another fault,
> > and only updates its local TLB.
> >
> > Instead of triggering another fault, it's better to implement
> > update_mmu_tlb() to directly update the local TLB of the second
> > thread. Just do it.
> >
> > Suggested-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> > ---
> >   arch/loongarch/include/asm/pgtable.h | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
> > index 8ea57e2f0e04..946704bee599 100644
> > --- a/arch/loongarch/include/asm/pgtable.h
> > +++ b/arch/loongarch/include/asm/pgtable.h
> > @@ -412,6 +412,9 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
> >          __update_tlb(vma, address, ptep);
> >   }
> >
> > +#define __HAVE_ARCH_UPDATE_MMU_TLB
> > +#define update_mmu_tlb update_mmu_cache
> > +
> >   static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
> >                          unsigned long address, pmd_t *pmdp)
> >   {
> > --
> > 2.20.1

--
Thanks,
Qi