From: David Hildenbrand <david@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Alex Williamson <alex.williamson@redhat.com>,
John Hubbard <jhubbard@nvidia.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [GIT PULL] VFIO fix for v6.0-rc5
Date: Fri, 9 Sep 2022 14:02:54 +0200 [thread overview]
Message-ID: <30566203-bbf6-786e-d4b7-f0003ee35e37@redhat.com> (raw)
In-Reply-To: <CAHk-=wj3rrkPvPJB_u4qoHK4=PVUuBHKB67f_oZO62EE22pNPQ@mail.gmail.com>
On 09.09.22 13:53, Linus Torvalds wrote:
> On Fri, Sep 9, 2022 at 6:52 AM Alex Williamson
> <alex.williamson@redhat.com> wrote:
>>
>> VFIO fix for v6.0-rc5
>>
>> - Fix zero page refcount leak (Alex Williamson)
>
> Ugh. This is disgusting.
>
> Don't get me wrong - I've pulled this, but I think there's some deeper
> problem that made this patch required.
>
> Why is pin_user_pages_remote() taking a reference to a reserved page?
> Maybe it just shouldn't (and then obviously we should fix the unpin
> case to match too).
>
> Adding a few GUP people to the participants for comments.
>
> Anybody?
I mentioned in an offline discussion to Alex that we should teach the
pin/unpin interface to not mess with the zeropage at all (i.e., not
adjust the refcount and eventually overflow it).
We decided that the unbalanced pin/unpin should be fixed independently,
such that the refcount handling change on pin/unpin stays GUP internal.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2022-09-09 12:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-09 10:52 Alex Williamson
2022-09-09 11:53 ` Linus Torvalds
2022-09-09 12:02 ` David Hildenbrand [this message]
2022-09-09 18:58 ` John Hubbard
2022-09-09 12:08 ` Alex Williamson
2022-09-09 14:31 ` Jason Gunthorpe
2022-09-09 11:59 ` pr-tracker-bot
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