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b=clSdgr69kSQSoDhvquHeZByZ0Vz2GrWz3kkc55A0xvhOVQgmWEq9Iuwy6fP3Q/IpD IQ/IwPtUEJhIKkmWeLrahrtasT1Rfk/xzWURNFmWDx/gUFUGUjLvLwH9pVOOU7nN0Z qHX8vh75+MZ/vWx/46bNUfHsJzyHLL0Cs5khhC8/CtCH9NfIN5wWfCYiiluJfnSA5b 9m3/0T3iNRZMNdRpAq3KA//nJWZlPscSzMfVdzZ36l7AoQ8H2a1D9ppMmnj7dPbkHU DmTbG0OGk97t/v5SgLfI06DbWkEnzJoAaFp//jPBzTequQ/MgWpgd6QHLQfq48DeWX uv0L4h6daO9cA== Message-ID: <0aa5b55f-54a4-4d39-885b-817c0191cdeb@kernel.org> Date: Fri, 25 Sep 2026 12:53:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/7] sched/numa: separate VMA placement from scan continuation To: Gregory Price , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.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, hannes@cmpxchg.org, shy828301@gmail.com, raghavendra.kt@amd.com, stable@vger.kernel.org References: <20260922182928.2199090-1-gourry@gourry.net> <20260922182928.2199090-5-gourry@gourry.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: w7yocjqz4fts1wpc3diwyzhupgprn6a9 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 86055C000B X-HE-Tag: 1790333613-670109 X-HE-Meta: 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 WM7z9ulf aq/zGJ8uzIQD1DY3f4C3I3K6X8qyTO7Y3A/iDUtxztRhmW0kkd54hNVZaJRkqpAzagXVQ6dvjeJO42MuO1UsStgCd9p0DuQuRo532kvxBd9pXkbwBRoWxRzxmpMkW+83zJvjxzwUMK8dpQL3d6VOKkNvb9GQoeaX7uMoCFjyiL1Dr1P8mxCaMEwBaCnCQLivpLyPaHEsWq8aJ6o6LgItmLou5q4Ia3iPgYdn8bIW2wzrskeg6PlM+yTx1+6gyZAJoDfvtywIIrtOH4ze63xPLlL8wmaD0jdkXH/XrsKJdvSnqCVLOiqV2vdfRiZHZp/37dp+YIiD+bf7WRfI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > /* > - * Do not scan the VMA if task has not accessed it, unless no other > - * VMA candidate exists. > + * Do not scan the VMA if a task has not accessed it, unless no other > + * VMA candidate exists. If a scan is already in-progress, finish it, > + * but track continuation separately from starting a new one. > */ > - if (!vma_pids_forced && !vma_is_accessed(mm, vma)) { > - vma_pids_skipped = true; > - trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE); > - continue; > + placement_due = vma_needs_placement_scan(mm, vma); > + scan_started = mm->numa_scan_offset > vma->vm_start; > + pid_scan_allowed = vma_pids_forced || placement_due; > + > + if (!pid_scan_allowed) { > + if (scan_started) { > + trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_IGNORE_PID); > + } else { > + vma_pids_skipped = true; > + trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE); > + continue; > + } > } > > + /* Keep scan policy stable while processing a VMA in chunks.*/ > placement_scan &= numab_mode & NUMA_BALANCING_NORMAL; > + if (scan_started) > + placement_scan &= vma->numab_state->placement_scan; Besides avoiding the "&=" in all cases to make the code readable, nothing caught my attention. It's all very complicated, so I won't pretend I fully digested the logic :) -- Cheers, David