From: Jonathan Cameron <jonathan.cameron@huawei.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Cui Chao <cuichao1753@phytium.com.cn>,
Andrew Morton <akpm@linux-foundation.org>,
<wangyinfeng@phytium.com.cn>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: numa_memblks: Identify the accurate NUMA ID of CFMW
Date: Mon, 5 Jan 2026 09:59:00 +0000 [thread overview]
Message-ID: <20260105095900.00005c09@huawei.com> (raw)
In-Reply-To: <aVuFv7P6og6pY2lj@kernel.org>
On Mon, 5 Jan 2026 11:34:55 +0200
Mike Rapoport <rppt@kernel.org> wrote:
> On Mon, Jan 05, 2026 at 10:38:30AM +0800, Cui Chao wrote:
> > Hi,
> >
> > Thank you for your review.
> >
> > On 12/30/2025 11:18 PM, Mike Rapoport wrote:
> > > Hi,
> > >
> > > On Tue, Dec 30, 2025 at 05:27:50PM +0800, Cui Chao wrote:
> > > > In some physical memory layout designs, the address space of CFMW
> > > > resides between multiple segments of system memory belonging to
> > > > the same NUMA node. In numa_cleanup_meminfo, these multiple segments
> > > > of system memory are merged into a larger numa_memblk. When
> > > > identifying which NUMA node the CFMW belongs to, it may be incorrectly
> > > > assigned to the NUMA node of the merged system memory. To address this
> > > Can you please provide an example of such memory layout?
> >
> > Example memory layout:
> >
> > Physical address space:
> > 0x00000000 - 0x1FFFFFFF System RAM (node0)
> > 0x20000000 - 0x2FFFFFFF CXL CFMW (node2)
> > 0x40000000 - 0x5FFFFFFF System RAM (node0)
> > 0x60000000 - 0x7FFFFFFF System RAM (node1)
> >
> > After numa_cleanup_meminfo, the two node0 segments are merged into one:
> > 0x00000000 - 0x5FFFFFFF System RAM (node0) // CFMW is inside this
> > range
> > 0x60000000 - 0x7FFFFFFF System RAM (node1)
> >
> > So the CFMW (0x20000000-0x2FFFFFFF) will be incorrectly assigned to node0.
>
> Can you please add this example to the changelog? #
Also, please +CC linux-cxl@vger.kernel.org given this is all about how
we handle the CXL fixed memory windows.
>
> > > > scenario, accurately identifying the correct NUMA node can be achieved
> > > > by checking whether the region belongs to both numa_meminfo and
> > > > numa_reserved_meminfo.
> > > >
> > > > Signed-off-by: Cui Chao <cuichao1753@phytium.com.cn>
>
prev parent reply other threads:[~2026-01-05 9:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-30 9:27 Cui Chao
2025-12-30 15:18 ` Mike Rapoport
2026-01-05 2:38 ` Cui Chao
2026-01-05 9:34 ` Mike Rapoport
2026-01-05 9:59 ` Jonathan Cameron [this message]
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