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Date:   Tue, 7 May 2019 19:43:36 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Sasha Levin <sashal@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Alexander Duyck <alexander.duyck@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        stable <stable@vger.kernel.org>,
        Mikhail Zaslonko <zaslonko@linux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        Pasha Tatashin <Pavel.Tatashin@microsoft.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Sasha Levin <alexander.levin@microsoft.com>,
        linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH AUTOSEL 4.14 62/95] mm, memory_hotplug: initialize struct
 pages for the full memory section
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On Tue 07-05-19 10:36:55, Matthew Wilcox wrote:
> On Tue, May 07, 2019 at 07:32:24PM +0200, Michal Hocko wrote:
> > On Tue 07-05-19 13:18:06, Sasha Levin wrote:
> > > Michal, is there a testcase I can plug into kselftests to make sure we
> > > got this right (and don't regress)? We care a lot about memory hotplug
> > > working right.
> > 
> > As said in other email. The memory hotplug tends to work usually. It
> > takes unexpected memory layouts which trigger corner cases. This makes
> > testing really hard.
> 
> Can we do something with qemu?  Is it flexible enough to hotplug memory
> at the right boundaries?

No idea. But I have tried to describe those layouts in the changelog so
if somebody can come up with a way to reproduce them under kvm/qemu I
would really appreciate that.

-- 
Michal Hocko
SUSE Labs