Re: [PATCH 4/4] arm64: support batched/deferred tlb shootdown during page reclamation

From: Barry Song <21cnbao@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>,
	LAK <linux-arm-kernel@lists.infradead.org>, x86 <x86@kernel.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Linux Doc Mailing List" <linux-doc@vger.kernel.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Arnd Bergmann" <arnd@arndb.de>,
	LKML <linux-kernel@vger.kernel.org>,
	"Darren Hart" <darren@os.amperecomputing.com>,
	"Yicong Yang" <yangyicong@hisilicon.com>,
	huzhanyuan@oppo.com, "李培锋(wink)" <lipeifeng@oppo.com>,
	"张诗明(Simon Zhang)" <zhangshiming@oppo.com>, 郭健 <guojian@oppo.com>,
	"real mz" <realmz6@gmail.com>,
	"Barry Song" <v-songbaohua@oppo.com>,
	"Nadav Amit" <namit@vmware.com>, "Mel Gorman" <mgorman@suse.de>
Subject: Re: [PATCH 4/4] arm64: support batched/deferred tlb shootdown during page reclamation
Date: Fri, 8 Jul 2022 09:10:23 +1200	[thread overview]
Message-ID: <CAGsJ_4zamtJcYvsR0xhMmRATjVnuEsaDdC9SkSSQwE4h1EMOxQ@mail.gmail.com> (raw)
In-Reply-To: <Ysbkbt7cvUWSShtc@hirez.programming.kicks-ass.net>

On Fri, Jul 8, 2022 at 1:50 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Fri, Jul 08, 2022 at 12:52:42AM +1200, Barry Song wrote:
>
> > diff --git a/arch/arm64/include/asm/tlbbatch.h b/arch/arm64/include/asm/tlbbatch.h
> > new file mode 100644
> > index 000000000000..fedb0b87b8db
> > --- /dev/null
> > +++ b/arch/arm64/include/asm/tlbbatch.h
> > @@ -0,0 +1,12 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _ARCH_ARM64_TLBBATCH_H
> > +#define _ARCH_ARM64_TLBBATCH_H
> > +
> > +struct arch_tlbflush_unmap_batch {
> > +     /*
> > +      * For arm64, HW can do tlb shootdown, so we don't
> > +      * need to record cpumask for sending IPI
> > +      */
> > +};
> > +
> > +#endif /* _ARCH_ARM64_TLBBATCH_H */
> > diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> > index 412a3b9a3c25..b3ed163267ca 100644
> > --- a/arch/arm64/include/asm/tlbflush.h
> > +++ b/arch/arm64/include/asm/tlbflush.h
> > @@ -272,6 +272,19 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
> >       dsb(ish);
> >  }
> >
> > +static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch,
> > +                                     struct mm_struct *mm,
> > +                                     struct vm_area_struct *vma,
> > +                                     unsigned long uaddr)
> > +{
> > +     flush_tlb_page_nosync(vma, uaddr);
> > +}
>
> You're passing that vma along just to get the mm, that's quite silly and
> trivially fixed.

Yes, this was silly. will include your fix in v2.

>
>
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index 412a3b9a3c25..87505ecce1f0 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -254,17 +254,23 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
>         dsb(ish);
>  }
>
> -static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
> -                                        unsigned long uaddr)
> +static inline void __flush_tlb_page_nosync(struct mm_struct *mm,
> +                                          unsigned long uaddr)
>  {
>         unsigned long addr;
>
>         dsb(ishst);
> -       addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
> +       addr = __TLBI_VADDR(uaddr, ASID(mm));
>         __tlbi(vale1is, addr);
>         __tlbi_user(vale1is, addr);
>  }
>
> +static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
> +                                        unsigned long uaddr)
> +{
> +       return __flush_tlb_page_nosync(vma->vm_mm, uaddr);
> +}
> +
>  static inline void flush_tlb_page(struct vm_area_struct *vma,
>                                   unsigned long uaddr)
>  {

Thanks
Barry