Date:   Thu, 2 Dec 2021 10:38:15 +0000
From:   Jeremy Sowden <jeremy@azazel.net>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Bixuan Cui <cuibixuan@linux.alibaba.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
        leon@kernel.org, w@1wt.eu, keescook@chromium.org,
        bpf@vger.kernel.org, netdev@vger.kernel.org,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jakub Kicinski <kuba@kernel.org>, kvm@vger.kernel.org,
        netfilter-devel@vger.kernel.org
Subject: Re: [PATCH -next] mm: delete oversized WARN_ON() in kvmalloc() calls
Message-ID: <YaiiFxD7jfFT9cSR@azazel.net>
References: <1638410784-48646-1-git-send-email-cuibixuan@linux.alibaba.com>
 <20211201192643.ecb0586e0d53bf8454c93669@linux-foundation.org>
 <10cb0382-012b-5012-b664-c29461ce4de8@linux.alibaba.com>
 <20211201202905.b9892171e3f5b9a60f9da251@linux-foundation.org>
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On 2021-12-01, at 20:29:05 -0800, Andrew Morton wrote:
> On Thu, 2 Dec 2021 12:05:15 +0800 Bixuan Cui wrote:
> > =E5=9C=A8 2021/12/2 =E4=B8=8A=E5=8D=8811:26, Andrew Morton =E5=86=99=E9=
=81=93:
> > >> Delete the WARN_ON() and return NULL directly for oversized
> > >> parameter in kvmalloc() calls.
> > >> Also add unlikely().
> > >>
> > >> Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
> > >> Signed-off-by: Bixuan Cui<cuibixuan@linux.alibaba.com>
> > >> ---
> > >> There are a lot of oversize warnings and patches about kvmalloc()
> > >> calls recently. Maybe these warnings are not very necessary.
> > >
> > > Or maybe they are.  Please let's take a look at these warnings,
> > > one at a time.  If a large number of them are bogus then sure,
> > > let's disable the runtime test.  But perhaps it's the case that
> > > calling code has genuine issues and should be repaired.
> >
> > Such as=EF=BC=9A
>
> Thanks, that's helpful.
>
> Let's bring all these to the attention of the relevant developers.
>
> If the consensus is "the code's fine, the warning is bogus" then let's
> consider retiring the warning.
>
> If the consensus is otherwise then hopefully they will fix their stuff!
>
> > https://syzkaller.appspot.com/bug?id=3D24452f89446639c901ac07379ccc7028=
08471e8e
>
> (cc bpf@vger.kernel.org)
>
> > https://syzkaller.appspot.com/bug?id=3Df7c5a86e747f9b7ce333e7295875cd4e=
de2c7a0d
>
> (cc netdev@vger.kernel.org, maintainers)
>
> > https://syzkaller.appspot.com/bug?id=3D8f306f3db150657a1f6bbe1927467084=
531602c7
>
> (cc kvm@vger.kernel.org)
>
> > https://syzkaller.appspot.com/bug?id=3D6f30adb592d476978777a1125d1f680e=
dfc23e00
>
> (cc netfilter-devel@vger.kernel.org)

The netfilter bug has since been fixed:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?i=
d=3D7bbc3d385bd813077acaf0e6fdb2a86a901f5382

> > https://syzkaller.appspot.com/bug?id=3D4c9ab8c7d0f8b551950db06559dc9cde=
4119ac83
>
> (bpf again).

J.

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