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From:   Pavel Tatashin <pasha.tatashin@soleen.com>
Date:   Wed, 2 Sep 2020 08:34:34 -0400
Message-ID: <CA+CK2bB4bSUHc8wONCdbBXtnxmR_dvxVVW2mKs_hGnyG0+Gv6g@mail.gmail.com>
Subject: Re: [PATCH v2 00/28] The new cgroup slab memory controller
To:     Bharata B Rao <bharata@linux.ibm.com>
Cc:     Roman Gushchin <guro@fb.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Shakeel Butt <shakeelb@google.com>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Kernel Team <Kernel-team@fb.com>,
        Yafang Shao <laoar.shao@gmail.com>,
        stable <stable@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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> I am on an old codebase that already has the fix that you are proposing,
> so I might be seeing someother issue which I will debug further.
>
> So looks like the loop in __offline_pages() had a call to
> drain_all_pages() before it was removed by
>
> c52e75935f8d: mm: remove extra drain pages on pcp list

I see, thanks. There is a reason to have the second drain, my fix is a
little better as it is performed only on a rare occasion when it is
needed, but I should add a FIXES tag. I have not checked
alloc_contig_range race.