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Date: Mon, 30 Mar 2020 16:04:56 +0800
From: Baoquan He <bhe@redhat.com>
Subject: Re: [PATCH v3 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by
 default for NUMA
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To: Michal Hocko <mhocko@kernel.org>
Cc: Hoan Tran <Hoan@os.amperecomputing.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Andrew Morton <akpm@linux-foundation.org>, Vlastimil Babka <vbabka@suse.cz>, Oscar Salvador <osalvador@suse.de>, Pavel Tatashin <pavel.tatashin@microsoft.com>, Mike Rapoport <rppt@linux.ibm.com>, Alexander Duyck <alexander.h.duyck@linux.intel.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>, "David S. Miller" <davem@davemloft.net>, Heiko Carstens <heiko.carstens@de.ibm.com>, Vasily Gorbik <gor@linux.ibm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, lho@amperecomputing.com, mmorana@amperecomputing.com

On 03/30/20 at 09:44am, Michal Hocko wrote:
> On Sun 29-03-20 08:19:24, Baoquan He wrote:
> > On 03/28/20 at 11:31am, Hoan Tran wrote:
> > > In NUMA layout which nodes have memory ranges that span across other nodes,
> > > the mm driver can detect the memory node id incorrectly.
> > > 
> > > For example, with layout below
> > > Node 0 address: 0000 xxxx 0000 xxxx
> > > Node 1 address: xxxx 1111 xxxx 1111
> > 
> > Sorry, I read this example several times, but still don't get what it
> > means. Can it be given with real hex number address as an exmaple? I
> > mean just using the memory layout you have seen from some systems. The
> > change looks interesting though.
> 
> Does this make it more clear?
>            physical address range and its node associaion
>          [0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1]

I later read it again, have got what Hoan is trying to say, thanks.

I think the change in this patchset makes sense, still have some concern
though, let me add comment in other thread.