linux-kernel - Re: [PATCH] vmemmap, memory_hotplug: fallback to base pages for vmmap

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Message-ID: <20170711172623.GB961@cmpxchg.org>
Date:   Tue, 11 Jul 2017 13:26:23 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Cristopher Lameter <cl@...ux.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] vmemmap, memory_hotplug: fallback to base pages for vmmap

Hi Michael,

On Tue, Jul 11, 2017 at 04:25:58PM +0200, Michal Hocko wrote:
> Ohh, scratch that. The patch is bogus. I have completely missed that
> vmemmap_populate_hugepages already falls back to
> vmemmap_populate_basepages. I have to revisit the bug report I have
> received to see what happened apart from the allocation warning. Maybe
> we just want to silent that warning.

Yep, this should be fixed in 8e2cdbcb86b0 ("x86-64: fall back to
regular page vmemmap on allocation failure").

I figure it's good to keep some sort of warning there, though, as it
could have performance implications when we fall back to base pages.