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From:   Naresh Kamboju <naresh.kamboju@linaro.org>
Date:   Thu, 2 Jul 2020 21:28:05 +0530
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Subject: Re: PANIC: mm: memcg/slab: percpu_ref_put_many - Unable to handle
 kernel paging request at virtual address ffff80096d78f000
To:     Roman Gushchin <guro@fb.com>, Michal Hocko <mhocko@kernel.org>
Cc:     Christoph Lameter <cl@linux.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Shakeel Butt <shakeelb@google.com>,
        linux-mm <linux-mm@kvack.org>, Vlastimil Babka <vbabka@suse.cz>,
        Kernel Team <kernel-team@fb.com>,
        open list <linux-kernel@vger.kernel.org>,
        Yafang Shao <laoar.shao@gmail.com>,
        lkft-triage@lists.linaro.org,
        Andrew Morton <akpm@linux-foundation.org>
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On Wed, 1 Jul 2020 at 13:49, Michal Hocko <mhocko@kernel.org> wrote:
>
> On Wed 01-07-20 13:24:54, Naresh Kamboju wrote:
> > While running LTP mm test suite on arm64 Juno device the kernel panic
> > noticed on linux-next 20200630 tag.
>
> Can you try to bisect? The new memcg slab allocator series sounds like a
> potential candidate. One of the patches has changed the memcg reference
> counting which is showing up on the stack. This might be a side effect
> of something else of course but bisection would tell us more.

The reported problem is fixed by a patch proposed in this email thread.
https://lore.kernel.org/linux-mm/20200701184552.GA61684@carbon.DHCP.thefacebook.com/

- Naresh

>
> Thanks
>
> --
> Michal Hocko
> SUSE Labs