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b=ctemzI7jCDJfs27xjODFYQ/9/JiX8/3JMfYY/w0+N8fS5e8NzwdMIPMARW5iqPQuM AgBOKnW4ofAAWVzKPN9g7mWhJjKDbrcbnHYazu2jQvOFpO2yTAEaTq1xqmPm+2wOj2 fcOK7UtrrpVVLedHG4tY5mm0DNatUD50uAx2pFrn9LyYnNhyoGrsbwjIXuUmjobJp0 Su786sfVgxG84DhGFtEBmmL61xirCpoE7/FcS88ViBmOyVCL5uJuw32o2ZKJWUlRHm 4nRwvLFLWP4lAQ9doNMcsTuZm6oUEGMCHaSKHNbqQx/zOJekgP01YsAeb3iv3Ip1eS lC1xtaDC6TtUA== Date: Tue, 14 Apr 2026 15:37:14 +0300 From: Mike Rapoport To: Sang-Heon Jeon Cc: akpm@linux-foundation.org, djbw@kernel.org, mingo@kernel.org, linux-mm@kvack.org, Donghyeon Lee , Munhui Chae Subject: Re: [RFC PATCH 1/2] mm/fake-numa: fix under-allocation detection logic in uniform split Message-ID: References: <20260413154438.396031-1-ekffu200098@gmail.com> <20260413154438.396031-2-ekffu200098@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260413154438.396031-2-ekffu200098@gmail.com> X-Stat-Signature: gz86dpeikx3b1xkkw1bmpscw8aw9oc4m X-Rspamd-Queue-Id: 6D0FC40012 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1776170241-274594 X-HE-Meta: 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 MJk5/uhe 0CGhm4klLcBOtqF0yBDWYc3HrG5w7bSnLGg7vSygHhf/5uKIod4tp0PMXl5M2LltAqebvdRJGaIo7yF9xfMXifJlDY/flBFKJyYLvubf8n/Joz9jC4++xsuEOFk86uWqIs6e7NRwVbKZ6HrwPVyobRVnuMIoZeSxRtG4KP1vTZpUle4IMda9Fo2NqIgeSIl+bR/19XnzE1N0SYNynd4On+R5wsezJtVm7YAh6cTEUXBL7CcwmT0lFtQVODyADOFsg9gt4h7B93KOe9e/Nbw5sung7iCJv2tCCjJEdTPVDZykSO5TTUmVTPHFc5g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, On Tue, Apr 14, 2026 at 12:44:37AM +0900, Sang-Heon Jeon wrote: > When split NUMA node uniformly, split_nodes_size_interleave_uniform() > returns the next absolute node ID, not the number of nodes created. > > The previous under-allocation detection logic compares next absolute node I'd replace "previous" with "existing" > ID (ret) and request count (n), which only works when nid starts at 0. > > Fix under-allocation detection logic to compare the number of actually > created nodes (ret - nid) against the request count (n). It would be nice to have an example of memory configuration and numa=fake=nU that demonstrates the issue. > Signed-off-by: Sang-Heon Jeon > Reported-by: Donghyeon Lee > Reported-by: Munhui Chae > Fixes: cc9aec03e58f ("x86/numa_emulation: Introduce uniform split capability") # 4.19 > --- > mm/numa_emulation.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/numa_emulation.c b/mm/numa_emulation.c > index 703c8fa05048..e7f856c8f2a1 100644 > --- a/mm/numa_emulation.c > +++ b/mm/numa_emulation.c > @@ -416,7 +416,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) > n, &pi.blk[0], nid); > if (ret < 0) > break; > - if (ret < n) { > + if (ret - nid < n) { > pr_info("%s: phys: %d only got %d of %ld nodes, failing\n", > __func__, i, ret, n); > ret = -1; > -- > 2.43.0 > -- Sincerely yours, Mike.