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Date:   Wed, 9 Mar 2022 09:00:21 +0100
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To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        Khalid Aziz <khalid.aziz@oracle.com>
References: <20220308141437.144919-1-david@redhat.com>
 <CAHk-=wiA0KMVbLacK-Gi5_ZsZhXVi++6ePTtPrJkgf0az7r2ww@mail.gmail.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Subject: Re: [PATCH v1 00/15] mm: COW fixes part 2: reliable GUP pins of
 anonymous pages
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On 08.03.22 22:22, Linus Torvalds wrote:
> On Tue, Mar 8, 2022 at 6:14 AM David Hildenbrand <david@redhat.com> wrote:
>>
>> This series fixes memory corruptions when a GUP pin (FOLL_PIN) was taken
>> on an anonymous page and COW logic fails to detect exclusivity of the page
>> to then replacing the anonymous page by a copy in the page table [...]
> 
> From a cursory scan of the patches, this looks sane.

Thanks for skimming over the patches that quickly!

> 
> I'm not sure what the next step should be, but I really would like the
> people who do a lot of pinning stuff to give it a good shake-down.
> Including both looking at the patches, but very much actually running
> it on whatever test-cases etc you people have.
> 
> Please?

My proposal would be to pull it into -next early after we have
v5.18-rc1. I expect some minor clashes with folio changes that should go
in in the next merge window, so I'll have to rebase+resend either way,
and I'm planning on thoroughly testing at least on s390x as well.

We'd then have plenty of time to further review+test while in -next
until the v5.19 merge window opens up.

By that time I should also have my selftests cleaned up and ready, and
part 3 ready to improve the situation for FOLL_GET|FOLL_WRITE until we
have the full FOLL_GET->FOLL_PIN conversion from John (I'll most
probably sent out an early RFC of part 3 soonish). So we *might* be able
to have everything fixed in v5.19.

Last but not least, tools/cgroup/memcg_slabinfo.py as mentioned in patch
#10 still needs care due to the PG_slab reuse, but I consider that a
secondary concern (yet, it should be fixed and help from the Authors
would be appreciated ;) ).

-- 
Thanks,

David / dhildenb