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([110.9.142.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d3ae79f0cesm10029415ad.18.2026.08.14.06.38.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Aug 2026 06:38:01 -0700 (PDT) From: Sang-Heon Jeon To: Mike Rapoport , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 2/2] mm/mm_init: simplify ZONE_MOVABLE branch in zone_spanned_pages_in_node() Date: Fri, 14 Aug 2026 22:37:39 +0900 Message-ID: <20260814133744.2746782-3-ekffu200098@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260814133744.2746782-1-ekffu200098@gmail.com> References: <20260814133744.2746782-1-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 *zone_start_pfn and *zone_end_pfn are first assigned clamp(node_start_pfn, zone_low, zone_high) and clamp(node_end_pfn, zone_low, zone_high). If movable_pfn != 0, the branches adjust them as follows. 1. If zone_type == ZONE_MOVABLE, *zone_start_pfn = movable_pfn, which can be outside the node, and *zone_end_pfn = min(node_end_pfn, ...), which is at most node_end_pfn. 2. Else If *zone_start_pfn < movable_pfn < *zone_end_pfn, *zone_end_pfn = movable_pfn. 3. Else If *zone_start_pfn >= movable_pfn, *zone_start_pfn = *zone_end_pfn. 4. Else *zone_start_pfn < movable_pfn && *zone_end_pfn <= movable_pfn, and nothing is assigned. If node_end_pfn < zone_low or node_start_pfn > zone_high, *zone_start_pfn and *zone_end_pfn are both zone_low or both zone_high, outside the node. Then case 2 cannot apply, in case 3 *zone_start_pfn = *zone_end_pfn, which is that same pfn, and in case 4 nothing is assigned. So the check against node_start_pfn and node_end_pfn returns 0 early. Otherwise node_start_pfn <= *zone_start_pfn <= *zone_end_pfn <= node_end_pfn. Then in case 2 *zone_end_pfn = movable_pfn, in case 3 *zone_start_pfn = *zone_end_pfn, and in case 4 nothing is assigned. So *zone_start_pfn and *zone_end_pfn stay within the node, the check does not return 0, and min(*zone_end_pfn, node_end_pfn) and max(*zone_start_pfn, node_start_pfn) change nothing. So the check, min(*zone_end_pfn, node_end_pfn), and max(*zone_start_pfn, node_start_pfn) only have an effect in case 1. Also, cases 2 and 4 both have *zone_start_pfn < movable_pfn, and min(*zone_end_pfn, movable_pfn) is movable_pfn in case 2 and *zone_end_pfn in case 4. So the two cases can be merged into one branch and case 3 becomes its else. So remove *zone_end_pfn = min(*zone_end_pfn, node_end_pfn), move the check and *zone_start_pfn = max(*zone_start_pfn, node_start_pfn) inside the ZONE_MOVABLE branch, and merge cases 2 and 4 with *zone_end_pfn = min(*zone_end_pfn, movable_pfn). No functional change. Signed-off-by: Sang-Heon Jeon --- mm/mm_init.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index df67d4e6f646..ab445111a846 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1208,25 +1208,24 @@ static unsigned long __init zone_spanned_pages_in_node(int nid, *zone_end_pfn = min(node_end_pfn, arch_zone_highest_possible_pfn[movable_zone]); - /* Adjust for ZONE_MOVABLE starting within this range */ - } else if (*zone_start_pfn < movable_pfn && - *zone_end_pfn > movable_pfn) { - *zone_end_pfn = movable_pfn; + /* Check that this node has pages within the zone's required range */ + if (*zone_end_pfn < node_start_pfn || + *zone_start_pfn > node_end_pfn) + return 0; - /* Check if this whole range is within ZONE_MOVABLE */ - } else if (*zone_start_pfn >= movable_pfn) { + /* Move the zone start inside the node if necessary */ + *zone_start_pfn = max(*zone_start_pfn, node_start_pfn); + + /* This range starts below ZONE_MOVABLE */ + } else if (*zone_start_pfn < movable_pfn) { + *zone_end_pfn = min(*zone_end_pfn, movable_pfn); + + /* This whole range is within ZONE_MOVABLE */ + } else { *zone_start_pfn = *zone_end_pfn; } out: - /* Check that this node has pages within the zone's required range */ - 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); - *zone_start_pfn = max(*zone_start_pfn, node_start_pfn); - /* Return the spanned pages */ return *zone_end_pfn - *zone_start_pfn; } -- 2.43.0