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From:   Shakeel Butt <shakeelb@google.com>
Date:   Mon, 6 Jun 2022 22:58:45 -0700
Message-ID: <CALvZod7+tpgKSQpMAgNKDtcsimcSjoh4rbKmUsy3G=QcRHci+Q@mail.gmail.com>
Subject: Re: [PATCH memcg v6] net: set proper memcg for net_init hooks allocations
To:     Vasily Averin <vvs@openvz.org>
Cc:     Qian Cai <quic_qiancai@quicinc.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Andrew Morton <akpm@linux-foundation.org>, kernel@openvz.org,
        LKML <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>,
        Florian Westphal <fw@strlen.de>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Eric Dumazet <edumazet@google.com>,
        Cgroups <cgroups@vger.kernel.org>
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On Mon, Jun 6, 2022 at 11:45 AM Vasily Averin <vvs@openvz.org> wrote:
>
[...]
>
> As far as I understand this report means that 'init_net' have incorrect
> virtual address on arm64.

So, the two call stacks tell the addresses belong to the kernel
modules (nfnetlink and nf_tables) whose underlying memory is allocated
through vmalloc and virt_to_page() does not work on vmalloc()
addresses.

>
> Roman, Shakeel, I need your help
>
> Should we perhaps verify kaddr via virt_addr_valid() before using virt_to_page()
> If so, where it should be checked?

I think virt_addr_valid() check in mem_cgroup_from_obj() should work
but I think it is expensive on the arm64 platform. The cheaper and a
bit hacky way to avoid such addresses is to directly use
is_vmalloc_addr() directly.