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In-Reply-To: <20180515125541.GH12670@dhcp22.suse.cz>
From:   Pavel Tatashin <pasha.tatashin@oracle.com>
Date:   Tue, 15 May 2018 11:59:25 -0400
Message-ID: <CAGM2reYGFjG38FW0nEf1gwRMfDyVQ7QCGZ83VewxXgedeT=Zsg@mail.gmail.com>
Subject: Re: [PATCH v2] mm: allow deferred page init for vmemmap only
To:     mhocko@kernel.org
Cc:     Steven Sistare <steven.sistare@oracle.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, tglx@linutronix.de,
        Linux Memory Management List <linux-mm@kvack.org>,
        mgorman@techsingularity.net, mingo@kernel.org,
        peterz@infradead.org, Steven Rostedt <rostedt@goodmis.org>,
        Fengguang Wu <fengguang.wu@intel.com>,
        Dennis Zhou <dennisszhou@gmail.com>
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> This will always be a maze as the early boot tends to be. Sad but true.
> That is why I am not really convinced we should use a large hammer and
> disallow deferred page initialization just because UP implementation of
> pcp does something too early. We should instead rule that one odd case.
> Your patch simply doesn't rule a large class of potential issues. It
> just rules out a potentially useful feature for an odd case. See my
> point?

Hi Michal,

OK, I will send an updated patch with disabling deferred pages only whe
NEED_PER_CPU_KM. Hopefully, we won't see similar issues in other places.

Thank you,
Pavel