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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-532ae750944sm6431301cf.25.2026.09.18.14.42.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Sep 2026 14:42:23 -0700 (PDT) Date: Fri, 18 Sep 2026 17:42:20 -0400 From: Gregory Price To: Zi Yan Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "kernel-team@meta.com" , "akpm@linux-foundation.org" , "david@kernel.org" , "ljs@kernel.org" , "liam@infradead.org" , "vbabka@kernel.org" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "mingo@redhat.com" , "peterz@infradead.org" , "juri.lelli@redhat.com" , "vincent.guittot@linaro.org" , "dietmar.eggemann@arm.com" , "rostedt@goodmis.org" , "bsegall@google.com" , "mgorman@suse.de" , "vschneid@redhat.com" , "kprateek.nayak@amd.com" , "baolin.wang@linux.alibaba.com" , "nico.pache@linux.dev" , "ryan.roberts@arm.com" , "dev.jain@arm.com" , "baohua@kernel.org" , "lance.yang@linux.dev" , "usama.arif@linux.dev" , "kas@kernel.org" , "matthew.brost@intel.com" , "joshua.hahnjy@gmail.com" , "rakie.kim@sk.com" , "byungchul@sk.com" , "ying.huang@linux.alibaba.com" , Alistair Popple , "jannh@google.com" , "pfalcato@suse.de" , "osalvador@suse.de" , "hannes@cmpxchg.org" , "raghavendra.kt@amd.com" Subject: Re: [PATCH v2 0/4] sched/numa: stop VMA scan filters from gating promotion Message-ID: References: <20260911001826.2109390-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Sep 18, 2026 at 04:56:34PM -0400, Zi Yan wrote: > > > > Tested on a host with 768GB/256GB DRAM/CXL. > > Ran 2 ~430GB database workloads with large (>300GB) shmem VMAs. > > Do you just launch them without any additional NUMA control or NUMA > policy configuration, like using numactl? Just want to understand the > scope of the issue and how well the fixes are tested. It might be good > to have a list of expected behaviors for people/AI to check against. > We found these issues while testing fairness controls with Joshua's tiered memcg limits patches [1]. We were seeing very lopsided bandwidth utilization between tiers. When dropped all the memcg extensions and tested these patches by themselves, we found that numa balancing was completely broken - starting with Johannes' shmem fix [2]. Otherwise - No other numa controls are used on these workloads. - no numactl - no mbind()/set_mempolicy() - no cpuset.mems - etc These fixes impact the fault-injecting side (spraying PROT_NONE), not the fault-handling side. So mempolicy and cpuset doesn't really come into the picture. It's more of an internal-consistency issue for numab itself. ~Gregory [1] https://lore.kernel.org/all/20260807202059.2620949-1-joshua.hahnjy@gmail.com/ [2] https://lore.kernel.org/all/20260629163337.1264881-1-hannes@cmpxchg.org/