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Tue, 17 Feb 2026 10:19:10 -0800 (PST) Message-ID: Date: Tue, 17 Feb 2026 10:19:08 -0800 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/mempolicy: track page allocations per mempolicy To: Michal Hocko Cc: linux-mm@kvack.org, apopple@nvidia.com, akpm@linux-foundation.org, axelrasmussen@google.com, byungchul@sk.com, cgroups@vger.kernel.org, david@kernel.org, eperezma@redhat.com, gourry@gourry.net, jasowang@redhat.com, hannes@cmpxchg.org, joshua.hahnjy@gmail.com, Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, mst@redhat.com, rppt@kernel.org, muchun.song@linux.dev, zhengqi.arch@bytedance.com, rakie.kim@sk.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, surenb@google.com, virtualization@lists.linux.dev, vbabka@suse.cz, weixugc@google.com, xuanzhuo@linux.alibaba.com, ying.huang@linux.alibaba.com, yuanchu@google.com, ziy@nvidia.com, kernel-team@meta.com References: <20260212045109.255391-1-inwardvessel@gmail.com> <20260212045109.255391-2-inwardvessel@gmail.com> <3fe7c5dd-b184-4421-a21c-bafce6aa7b09@gmail.com> <9ae80317-f005-474c-9da1-95462138f3c6@gmail.com> Content-Language: en-US From: "JP Kobryn (Meta)" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/17/26 4:37 AM, Michal Hocko wrote: > On Mon 16-02-26 23:48:42, JP Kobryn (Meta) wrote: >> On 2/16/26 1:07 PM, Michal Hocko wrote: > [...] >>> [*] btw. I believe you misaccount MPOL_LOCAL because you attribute the >>> target node even when the allocation is from a remote node from the >>> "local" POV. >> >> It's a good point. The accounting as a result of fallback cases >> shouldn't detract from an investigation though. We're interested in the >> node(s) under pressure so the relatively few fallback allocations would >> land on nodes that are not under pressure and could be viewed as >> acceptable noise. > > This is really confusing. You simply have no means to tell the > difference between the requested node and the real node used so you > cannot really say whether the memory pressure is because of fallbacks or > your mempolicy configurations. That means that you cannot tell the > difference between the source of the pressure and victim of that > pressure. What if I excluded the fallback cases? I could get the actual node from the allocated page and compare against the requested node or node mask.