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Message-ID: <06185b08-8440-8922-c0aa-f6fb91aa54e0@redhat.com>
Date:   Mon, 16 Jan 2023 18:09:52 +0100
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Subject: Re: [PATCH v2] mm: do not try to migrate lru_gen if it's not
 associated with a memcg
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To:     Yu Zhao <yuzhao@google.com>, msizanoen1 <msizanoen@qtmlabs.xyz>
Cc:     Andrew Morton <akpm@linux-foundation.org>, stable@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <20230115133330.28420-1-msizanoen@qtmlabs.xyz>
 <20230115134651.30028-1-msizanoen@qtmlabs.xyz>
 <CAOUHufahcS0G_GApTdmzE4_Nb_70LGaCkgV0NR_xJuWN2NdJVg@mail.gmail.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <CAOUHufahcS0G_GApTdmzE4_Nb_70LGaCkgV0NR_xJuWN2NdJVg@mail.gmail.com>
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On 16.01.23 00:13, Yu Zhao wrote:
> On Sun, Jan 15, 2023 at 6:47 AM msizanoen1 <msizanoen@qtmlabs.xyz> wrote:
>>
>> In some cases, memory cgroup migration can be initiated by userspace
>> right after a process was created and right before `lru_gen_add_mm()` is
>> called (e.g. by some program watching a cgroup and moving away any
>> processes it detects[1]), which results in the following sequence of
>> WARNs followed by an Oops as the kernel attempts to perform a
>> `lru_gen_add_mm()` twice on the same `mm`:
> 
> ...
> 
>> Fix this by simply leaving the lru_gen alone if it has not been
>> associated with a memcg yet, as it should eventually be assigned to the
>> right cgroup anyway.
>>
>> [1]: https://gitlab.freedesktop.org/benzea/uresourced/-/blob/master/cgroupify/cgroupify.c
>>
>> v2:
>>          Added stable cc tags
>>
>> Signed-off-by: N/A (patch should not be copyrightable)
>> Cc: stable@vger.kernel.org
> 
> Thanks for the fix.  Cc'ing stable is the right thing to do. The
> commit message and the comment styles could be easily adjusted to
> align with the guidelines.
> 
> I don't think the N/A is acceptible though. I fully respect it if you
> wish to remain anonymous -- I can send a similar fix crediting you
> as the "anonymous user <msizanoen@qtmlabs.xyz>" who reported this bug.

Not acceptable:

Documentation/process/submitting-patches.rs

"using your real name (sorry, no pseudonyms or anonymous contributions.)"


-- 
Thanks,

David / dhildenb