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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c37f4b917dsm178740585a.17.2026.01.06.06.24.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Jan 2026 06:24:09 -0800 (PST) Date: Tue, 6 Jan 2026 09:23:34 -0500 From: Gregory Price To: Bing Jiao Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, longman@redhat.com, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, tj@kernel.org, mkoutny@suse.com, david@kernel.org, zhengqi.arch@bytedance.com, lorenzo.stoakes@oracle.com, axelrasmussen@google.com, chenridong@huaweicloud.com, yuanchu@google.com, weixugc@google.com, cgroups@vger.kernel.org Subject: Re: [PATCH v6] mm/vmscan: fix demotion targets checks in reclaim/demotion Message-ID: References: <20260105050203.328095-1-bingjiao@google.com> <20260106075703.1420072-1-bingjiao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260106075703.1420072-1-bingjiao@google.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: EC8C1180007 X-Stat-Signature: wddxkjkaj56ks5s5pi6bf9fzb9m3dw16 X-Rspam-User: X-HE-Tag: 1767709451-978835 X-HE-Meta: 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 S3VjU6Ga 5RVdfkdqe/koetTWX6GMvtfYTXIR2qHvPUM/S9oWnl78iF5iLfISqtaGrS1TPVHtwVK0FLaXnuCnBnFA7rKubrxTKB4d9437LO1moKAA63N1+Wnbn4qPhTf3kxQZ3SLGrKokgzIyvN67nJUBymbHY704Tmi5kcMTsC3Qfc5KVAmuPWbPyE8gxZCUUV6/esBahR3cvo1FEt1m/ZEvODiiai4mQEwZyHXNuc4Co4/nOD6nl6V1d4/UBWd+3ruADdxrznpkFK/HzSZA5rcLY5cPTYJewCXseC8g8Ap3M6ELgqgUyxLtG/iZ5ZlSwD8kdoSTA92VdNg4Cxr70MaQorGMneESlsxzbnwrlbzvB0epJETEvFCP7VfP/UWKAMy6AzDdpUnNCRFBRX9uV6w1CqkIJVaxcAxMg13NEC5WdxGk5iI3HU2hQ6PxUHn99+A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jan 06, 2026 at 07:56:54AM +0000, Bing Jiao wrote: > > Bug 1 reproduction: > Assume a system with 4 nodes, where nodes 0-1 are top-tier and > nodes 2-3 are far-tier memory. All nodes have equal capacity. > > Test script: > echo 1 > /sys/kernel/mm/numa/demotion_enabled > mkdir /sys/fs/cgroup/test > echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control > echo "0-2" > /sys/fs/cgroup/test/cpuset.mems > echo $$ > /sys/fs/cgroup/test/cgroup.procs > swapoff -a > # Expectation: Should respect node 0-2 limit. > # Observation: Node 3 shows significant allocation (MemFree drops) > stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1 > > Bug 2 reproduction: > Assume a system with 6 nodes, where nodes 0-2 are top-tier, > node 3 is a far-tier node, and nodes 4-5 are the farthest-tier nodes. > All nodes have equal capacity. > > Test script: > echo 1 > /sys/kernel/mm/numa/demotion_enabled > mkdir /sys/fs/cgroup/test > echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control > echo "0-2,4-5" > /sys/fs/cgroup/test/cpuset.mems > echo $$ > /sys/fs/cgroup/test/cgroup.procs > swapoff -a > # Expectation: Pages are demoted to Nodes 4-5 > # Observation: No pages are demoted before oom. > stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1,2 > > Fixes: 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim") > Cc: > Signed-off-by: Bing Jiao This looks ok now, haven't tested it myself yet, but looks good. Thank you for the fix. Reviewed-by: Gregory Price ~Gregory