From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 885EDC982CD for ; Thu, 17 Sep 2026 06:59:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 98C166B009B; Thu, 17 Sep 2026 02:59:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 93C7D6B009D; Thu, 17 Sep 2026 02:59:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 832D56B009E; Thu, 17 Sep 2026 02:59:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 536316B009B for ; Thu, 17 Sep 2026 02:59:52 -0400 (EDT) Received: from smtpin25.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id D5E448026D for ; Thu, 17 Sep 2026 06:59:51 +0000 (UTC) X-FDA: 85222354182.25.29BB638 Received: from mail-qk2-f12.google.com (mail-qk2-f12.google.com [74.125.230.204]) by imf05.hostedemail.com (Postfix) with ESMTP id 0A72C10000A for ; Thu, 17 Sep 2026 06:59:49 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=JE1Wx8to; dmarc=none; spf=pass (imf05.hostedemail.com: domain of gourry@gourry.net designates 74.125.230.204 as permitted sender) smtp.mailfrom=gourry@gourry.net ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1789628390; b=bppKVgAbz7GwJu/G462RmJavZlzCF42gQtuINvB8Q8BdPdJfMHCD9ft72UBx/RBAUdOy8u ptciiOzPZ4Lx+jMEL4rFp4XGg497iHDIRaC74JscrQS5lloZ/JYS84RnUnxHK2M9Q+W12L gQsAeWQGhi4kB12PKecY8A7zeeZPCzQ= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=JE1Wx8to; dmarc=none; spf=pass (imf05.hostedemail.com: domain of gourry@gourry.net designates 74.125.230.204 as permitted sender) smtp.mailfrom=gourry@gourry.net ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1789628390; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AKGEnw/rGHEkMgptaV8n9ekSmooVW4BhmhAnYjj/TSI=; b=AnHishSDSWt8W2EByshqDexrT7PU2up/mnRMCpnnNYEBmch6pkdZ9Qzq26h//ZRi7iWz4T yYFYb5BBkNio5PsbrgFTN2NV2tHyMX9Qc8o+PhmqoCCDfFVdXU+DECswbAc4//ve05YA90 T6hMseLlceqpReVIKv+AqdOdGMX/G04= Received: by mail-qk2-f12.google.com with SMTP id d75a77b69052e-531034aa31bso3523721cf.2 for ; Wed, 16 Sep 2026 23:59:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1789628389; x=1790233189; darn=kvack.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=AKGEnw/rGHEkMgptaV8n9ekSmooVW4BhmhAnYjj/TSI=; b=JE1Wx8tovuqlos6YVfi5lRazC2vIkCuGfn11KiQyxrVnHhGwzAX3fQISv7zLxSyZMI zMk6XW5zp3Wmntxt5KvR3HeHwUwipi3dyvjQ27jzKOyAVViqnhQtZElRtWhjfF+I13c6 rTEybiKHy55VIkUu9y9chdQdCptjX/fdwD5EsQvWy5yJpo+C9WJiVYAe+n/DhsjxBbOC W9Vg0quM9yOBcjNCB08nMmVeNWFHpBGnjTnLpPRQiuVW+zb9g16PIHHoGq5qjJ8/MPk6 QeRkibspOXiMMHRLmLGwmHj7tsxmPg4iTSNY6U9QIT21gyXW61KUl7Ci3+2cJgKnslx7 5pAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789628389; x=1790233189; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=AKGEnw/rGHEkMgptaV8n9ekSmooVW4BhmhAnYjj/TSI=; b=puB+9uJWFxOEmaAdu1PAAgH3ExL/WNGdI/xvnwFZtbRaUKjoNvU0pUv8VFgiEdiUpR NIl9VXhT916HP7i/DrYujsagwkeyIvjJxgxvnAlmmzP032mQriQRGG7wrSNnnvBJB1gq bQznKrve3y8DCb861TMZGphOPmgsWwNa3KuyFI4p7WOrMPFB59zY6FusrQ+e87LGKPfS +4MYgiD/B9KKVDn8v2nh67mMNxiq9kksUWniBrnNceYw+WDdFrhIWdPw2gzbCqRAJtrB qdfM11dQf3vpu05ctcKb9X5u3a1syxqS87lYiaO3FRsRVFB/ZVqax9TQWjprSp/z7OA0 2z5w== X-Gm-Message-State: AFuF++kcwcSakb8bYPnV8xi1+rSJXTNXwwEJ6efgtThblkvy6PmPx8T/ G4o8GcmD09aXPXuFLqkthn5s4l3P5bkhAFEMNm6Zw2pvD5WyYz3VMLb9I6JwEc6rNnc= X-Gm-Gg: AYBFou1qVlHNLdbqYVcVyXOGm7lH1ijeFRYas+U88XX/31/oRVmWW6ikBOLRlCnJhBH ZwtRBHmllFy3WAXq9h+AzHV45u9kOl3psvyouYh6g4o9yoFjfE2fD5jqnIgZe2g3aAwBzkqWRcf xUtj7GfEKs1OjkIkdyTXPyzHT4aRJZAFTSINIEIDa6S+bWadSgbvHk8muDXYJLJlpEgTyc9lIDa rovbRjCBaZT/4GvqwT+w2n92KXVdDECzeUeIL+4oclmQ9QqF2q7wKFQfxiD6gAufYMsYSuF91on VDDZ25CqaU9MCvDbJ31PdewRPZeMTdi9F5z1rJ3suYZ71s7VUJq3+r+CttK9TJ4P/bqB4Rr78WC xSu2Be/kO8NN9I0y+5QSh5UB12F7EwZeyrg/DARJ0+SZojhrG3hP/uoaqpcweBpuXrgmAiyC/07 nDQbOQqgUIUYilh1rxaslGlevZZSUEylrVLfp9ndlVtxN5alBr/LYT9rMoAyoNoWw+9i3P7kaoV vm6f+4OBXCJHm66/KEIbPaTdJcas5+l0dupcatyndLS/Q85RD+vo88= X-Received: by 2002:a05:622a:1388:b0:530:ea12:caad with SMTP id d75a77b69052e-5327f1622e2mr94436001cf.50.1789628389177; Wed, 16 Sep 2026 23:59:49 -0700 (PDT) Received: from gourry-fedora-PF4VCD3F (pool-173-79-60-52.washdc.fios.verizon.net. [173.79.60.52]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5326200b8d1sm41492531cf.12.2026.09.16.23.59.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2026 23:59:48 -0700 (PDT) Date: Thu, 17 Sep 2026 02:59:46 -0400 From: Gregory Price To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, 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, ziy@nvidia.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, apopple@nvidia.com, 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> <20260916223525.65ae1628b1457a716efc298f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260916223525.65ae1628b1457a716efc298f@linux-foundation.org> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 0A72C10000A X-Stat-Signature: 7wudq3nf7uy5yuq63xmbjndi4wfw4uq5 X-HE-Tag: 1789628389-69770 X-HE-Meta: U2FsdGVkX1+xhqwqagAITD7fPE8dn//gJUexj5pqrAHwz2+IYosgZIZkOXZvTJaCT0/ftHSqUcJYU1bKWBOnCJNVJbAV3sm10GsXuPAA7ZUQY5MUyF8VWJdqCXSsM2+xfKi2i2qT9asFQ1PLti8Ac/WxyIahxZf2/F4z2MiSPHbbIN/MuPG2aGAvuLmJXj5hsEDsEhjCEFxBJGmlv+xqPuCo3OXBsPQXNHD6vYy03IatHV5TtQXqsdEv+CvDrxJcFP2Wvrjco+gbRkidjBuf4Xj28fwJ9oE221KuOHWcfO+IqD8RhrOeNfWio5n+eJbJ0Kan/6tFqsL27uafgHjiuXbf/DJpkfQvWpSLJT2hvwwEyTMSC4UVKmAmViDgyrRW6Cp8lvBUI75XaWb7ao7ZQGF8nMv2BSXKxwe7cgiXi5M33M9EdaMf3t+KIWjyiiaQpdrjc4uHYf0qmqf2EIno2TBZyyhCFQCcyyNokKotP7VIaBMj/owkI6zyavp3PiQWBn12DSXyRg/cFzOrClP43oL91ZzNfjYonSMxJzRD0TiwOBhG8jUE/yVAImSZD8TuKVtyrqJkl4kYIy85bqTefkyLhmC8plWM1lTt3QmVOYDRX/xyJu2UY8pLNNbPScenuqI+DRC3l19yFPywYupTz9zB45ZxAGE1cobO2LKTX56x6Tr3aiWXnadTnkL20mnrevs7NglX2cObcObG4srte1VsJ5nZ0dyLhYniAnah9GQuKKbCo+hPavLC0ldLUYxww8Z6vrWjFGLleT6D0PDs0nUyRRBgV9aS3TZ4xxsmDG3eTcGaBtBel+VCk/vbpL9ORZ7B3APuOWcITbJ/Ev91svrnF/xla6bCbc/0PhN9rq1+LwNFmM8ME6KWLOxt7GKcBVbWrda186b0eafQW60t6QwUEwrbRi40bDQ7rFD+KjG9335cEZ4jf5JeNFUpADZGupnuMmVCIuT8mYaVlUU C9qGEzf2 JDX3drMKCX1yJjQSs47KGETQDfL+tUHkCm1xKnIJTyE8sOb1i//FN3/senPyi5quJ5bTO3rEOjas1qNhznpHwFW1YkTD3vGMGn21cjErGxyeqyQV4ibLHDdo4k5ylrNdC/MAAqX3+dqLGjN7Nqcl/bT/U9G1RowL71DtWlVZWGqFFCpiQ3eGb/vAuflq1Jo5B+s2rG9/qPxIvVF5YYNtowvWsWUEFGwfpTaFmw6KzKc+bTOEfcfhbdX1DVovFsHUJPmttW6oTIGQKBIyyQTO1cxC3Kkjvt11wTRjLg1sEnBf09r9DBXEeY5zhh7EfNnGSbEgJwYUHJmhJnvWAc1wLB4Ke8tVsfvBt6kr1xo5f8jBNgvMyKfAE7EbpIYnG3o5mUxYlzr0Gfoj0t9m5Ur8CthKmOA4tluaNjF7Fj6WWfgtnw8jNBIbKF2wReNbnkaoRjvhSm0RTkWjiFYCnPDb7NrptARA16aOoMIJTYCGWRegJIKnXXVpNSv8x0HuS/wCNLFH9Eq7BpNK/GxkmoxySQC7AoPxVP2C1n2Lh Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 16, 2026 at 10:35:25PM -0700, Andrew Morton wrote: > On Thu, 10 Sep 2026 20:18:22 -0400 Gregory Price wrote: > > > > > Functional observation: > > A 20 GB hash table VMA that previously remained entirely on CXL was > > split evenly between DRAM and CXL after the changes - and tier > > residency tracked hotness. This was previously affected by the > > stavation issue caused by the "unaccessed VMA" filter. > > This seems very significant? > > Why cc:stable and Fixes:? Is this something which ran at these sorts > of speeds before the offending commits? > It's actually that the changes functionally broke numa balancing to the point that it just became completely ineffective for very common use cases. We only didn't notice because another bug: https://lore.kernel.org/all/20260629163337.1264881-1-hannes@cmpxchg.org/ hid almost all these issues from being apparent on large workloads (which was differently horrendous - that bug made ~70-90% of some database workload memory ineligible for tiering) Once the shmem fix went in, all the starvation and filtering issues become more apparent when the bandwidth numbers stopped making sense (see above). Basically numa balancing has been broken since 2022/2023, and anyone who has done any testing with it since then has been working off of bad data (incomplete VMA coverage). ~Gregory