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([110.9.142.4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84f459b66e6sm1662739b3a.40.2026.08.06.09.21.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 09:21:23 -0700 (PDT) From: Sang-Heon Jeon To: Mike Rapoport , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 2/5] mm/mm_init: remove redundant clamping in zone_spanned_pages_in_node() Date: Fri, 7 Aug 2026 01:20:53 +0900 Message-ID: <20260806162100.313965-3-ekffu200098@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260806162100.313965-1-ekffu200098@gmail.com> References: <20260806162100.313965-1-ekffu200098@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Clamping *zone_end_pfn to node_end_pfn has no effect, because *zone_end_pfn <= node_end_pfn is guaranteed at that point. 1. If zone_movable_pfn[nid] != 0 && zone_type == ZONE_MOVABLE, *zone_end_pfn = min(node_end_pfn, ...) <= node_end_pfn. 2. Else If zone_movable_pfn[nid] != 0 && *zone_start_pfn < zone_movable_pfn[nid] < *zone_end_pfn, *zone_end_pfn = zone_movable_pfn[nid]. The condition requires the clamped *zone_start_pfn and *zone_end_pfn to differ, which cannot happen when node_end_pfn < zone_low. So zone_movable_pfn[nid] < clamped *zone_end_pfn = min(node_end_pfn, zone_high) <= node_end_pfn. 3. Else *zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high) a. If node_end_pfn >= zone_low, *zone_end_pfn = min(node_end_pfn, zone_high) <= node_end_pfn. b. If node_end_pfn < zone_low, *zone_start_pfn = zone_low > node_end_pfn, so the function returns 0 before the clamping is executed. So remove it. No functional change. Signed-off-by: Sang-Heon Jeon --- mm/mm_init.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 30d3125951f0..bdc15de0a62a 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1219,8 +1219,7 @@ static unsigned long __init zone_spanned_pages_in_node(int nid, if (*zone_end_pfn < node_start_pfn || *zone_start_pfn > node_end_pfn) return 0; - /* Move the zone boundaries inside the node if necessary */ - *zone_end_pfn = min(*zone_end_pfn, node_end_pfn); + /* Move the zone start inside the node if necessary */ *zone_start_pfn = max(*zone_start_pfn, node_start_pfn); /* Return the spanned pages */ -- 2.43.0