linux-kernel - Re: Arm64 crash while reading memory sysfs

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Date:   Tue, 15 Jun 2021 09:05:34 +0300
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Qian Cai <quic_qiancai@...cinc.com>,
        David Hildenbrand <david@...hat.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: Arm64 crash while reading memory sysfs

On Mon, Jun 14, 2021 at 05:13:51PM -0700, Andrew Morton wrote:
> On Mon, 14 Jun 2021 11:25:54 +0300 Mike Rapoport <rppt@...ux.ibm.com> wrote:
> 
> > On Tue, Jun 08, 2021 at 12:36:21PM +0530, Anshuman Khandual wrote:
> > > 
> > > 
> > > On 5/28/21 10:43 AM, Mike Rapoport wrote:
> > > > On Thu, May 27, 2021 at 03:56:44PM -0700, Andrew Morton wrote:
> > > >> On Thu, 27 May 2021 18:50:48 +0100 Catalin Marinas <catalin.marinas@....com> wrote:
> > > >>
> > > >>>> Can you please try Anshuman's patch "arm64/mm: Drop HAVE_ARCH_PFN_VALID":
> > > >>>>
> > > >>>> https://lore.kernel.org/lkml/1621947349-25421-1-git-send-email-anshuman.khandual@arm.com
> > > >>>>
> > > >>>> It seems to me that the check for memblock_is_memory() in
> > > >>>> arm64::pfn_valid() is what makes init_unavailable_range() to bail out for
> > > >>>> section parts that are not actually populated and then we have
> > > >>>> VM_BUG_ON_PAGE(PagePoisoned(p)) for these pages.
> > > >>>
> > > >>> I acked Anshuman's patch, I think they all need to go in together.
> > > >>
> > > >> That's neat.   Specifically which patches are we referring to here?
> > > > 
> > > > arm64: drop pfn_valid_within() and simplify pfn_valid():
> > > > https://lore.kernel.org/lkml/20210511100550.28178-5-rppt@kernel.org
> > > > 
> > > > arm64/mm: Drop HAVE_ARCH_PFN_VALID:
> > > > https://lore.kernel.org/lkml/1621947349-25421-1-git-send-email-anshuman.khandual@arm.com
> > > 
> > > I dont see the above patch (which drops HAVE_ARCH_PFN_VALID on arm64) on linux-next
> > > i.e. next-20210607. I might have missed some earlier context here but do not we want
> > > to fallback on generic pfn_valid() after Mike's series ?
> > 
> > Andrew,
> > 
> > Can you please pick the two patches above?
> 
> I already had
> 
> include-linux-mmzoneh-add-documentation-for-pfn_valid.patch
> memblock-update-initialization-of-reserved-pages.patch
> arm64-decouple-check-whether-pfn-is-in-linear-map-from-pfn_valid.patch
> arm64-drop-pfn_valid_within-and-simplify-pfn_valid.patch
> 
> and I just added
> 
> arm64-mm-drop-have_arch_pfn_valid.patch
> 
> so I think we're all good now?

Yes. 
 
> and I don't think any of this is needed in 5.13 or -stable, correct?

Right.
 
> I still have question marks over
> 
> https://lkml.kernel.org/r/YJ0Fhs5krPJ0FgiV@kernel.org and
> https://lkml.kernel.org/r/d55f915c-ad01-e729-1e29-b57d78257cbb@quicinc.com
> 
> Is this all OK now?

Yes, it is.

-- 
Sincerely yours,
Mike.