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From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
	 David Hildenbrand <david@kernel.org>,
	Lorenzo Stoakes <ljs@kernel.org>,
	 "Liam R. Howlett" <liam@infradead.org>,
	Vlastimil Babka <vbabka@kernel.org>,
	 Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	 Michal Hocko <mhocko@suse.com>, Kairui Song <kasong@tencent.com>,
	 Qi Zheng <qi.zheng@linux.dev>,
	Shakeel Butt <shakeel.butt@linux.dev>,
	 Barry Song <baohua@kernel.org>,
	Axel Rasmussen <axelrasmussen@google.com>,
	 Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
	 Baoquan He <baoquan.he@linux.dev>,
	 Baolin Wang <baolin.wang@linux.alibaba.com>,
	 Brendan Jackman <brendan.jackman@linux.dev>,
	 Johannes Weiner <hannes@cmpxchg.org>, Zi Yan <ziy@nvidia.com>,
	 Jan Kiszka <jan.kiszka@siemens.com>,
	Kieran Bingham <kbingham@kernel.org>,
	 Oscar Salvador <osalvador@suse.de>,
	 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	 "Rafael J. Wysocki" <rafael@kernel.org>,
	Danilo Krummrich <dakr@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	 linux-cxl@vger.kernel.org, driver-core@lists.linux.dev,
	 linux-fsdevel@vger.kernel.org
Subject: [PATCH v2 08/13] mm/sparse: move __highest_used_section_nr handling
Date: Mon, 21 Sep 2026 21:59:00 +0200	[thread overview]
Message-ID: <20260921-b4-sparsemem_cleanups-v2-8-54d81d65e125@kernel.org> (raw)
In-Reply-To: <20260921-b4-sparsemem_cleanups-v2-0-54d81d65e125@kernel.org>

In preparation for removing __section_mark_present(), let's move
__highest_used_section_nr handling into its callers. Verify in
sparse_init_one_section() that it was properly updated.

In sparse_sections_init() we can just set it to the last processed
section_nr.

No functional change intended.

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
 mm/sparse-vmemmap.c | 1 +
 mm/sparse.c         | 5 +++--
 mm/sparse.h         | 4 +---
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 96506f594924c..e89efb67e8e6d 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -865,6 +865,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
 		page_init_poison(memmap, sizeof(struct page) * nr_pages);
 
 	__section_mark_present(ms, section_nr);
+	__highest_used_section_nr = max(section_nr, __highest_used_section_nr);
 
 	/* Align memmap to section boundary in the subsection case */
 	if (section_nr_to_pfn(section_nr) != start_pfn)
diff --git a/mm/sparse.c b/mm/sparse.c
index bb89017254f4d..a0f50ca5acf5a 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -177,7 +177,7 @@ static inline unsigned long first_present_section_nr(void)
 
 void __init sparse_sections_init(void)
 {
-	unsigned long pfn, start_pfn, end_pfn;
+	unsigned long pfn, start_pfn, end_pfn, section_nr;
 	int i, nid;
 
 	sparse_extreme_init();
@@ -187,9 +187,9 @@ void __init sparse_sections_init(void)
 		mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
 
 		for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
-			unsigned long section_nr = pfn_to_section_nr(pfn);
 			struct mem_section *ms;
 
+			section_nr = pfn_to_section_nr(pfn);
 			sparse_index_init(section_nr, nid);
 			ms = __nr_to_section(section_nr);
 			if (ms->section_mem_map)
@@ -201,6 +201,7 @@ void __init sparse_sections_init(void)
 			__section_mark_present(ms, section_nr);
 		}
 	}
+	__highest_used_section_nr = section_nr;
 }
 #ifndef CONFIG_SPARSEMEM_VMEMMAP
 struct page __init *__populate_section_memmap(unsigned long pfn,
diff --git a/mm/sparse.h b/mm/sparse.h
index 242b7bab0013c..c396d5c05cfc8 100644
--- a/mm/sparse.h
+++ b/mm/sparse.h
@@ -26,6 +26,7 @@ static inline void sparse_init_one_section(struct mem_section *ms,
 	unsigned long coded_mem_map;
 
 	BUILD_BUG_ON(SECTION_MAP_LAST_BIT > PFN_SECTION_SHIFT);
+	VM_WARN_ON_ONCE(section_nr > __highest_used_section_nr);
 
 	/*
 	 * We encode the start PFN of the section into the mem_map such that
@@ -44,9 +45,6 @@ static inline void sparse_init_one_section(struct mem_section *ms,
 static inline void __section_mark_present(struct mem_section *ms,
 		unsigned long section_nr)
 {
-	if (section_nr > __highest_used_section_nr)
-		__highest_used_section_nr = section_nr;
-
 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
 }
 

-- 
2.43.0


  parent reply	other threads:[~2026-09-21 20:00 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-21 19:58 [PATCH v2 00/13] mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 01/13] mm/sparse: move mem_section init to sparse_extreme_init() David Hildenbrand (Arm)
2026-09-21 23:12   ` Zi Yan
2026-09-21 19:58 ` [PATCH v2 02/13] mm/sparse: refactor sparse_sections_init() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 03/13] mm/sparse: move initialization of section metadata to sparse_metadata_init() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 04/13] mm/sparse: rename and cleanup sparse_init_nid() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 05/13] mm/sparse: cleanup sparse_init_one_section() David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 06/13] mm/sparse: rename __highest_present_section_nr to __highest_used_section_nr David Hildenbrand (Arm)
2026-09-21 19:58 ` [PATCH v2 07/13] mm/sparse: remove pfn_in_present_section() David Hildenbrand (Arm)
2026-09-21 19:59 ` David Hildenbrand (Arm) [this message]
2026-09-22  4:24   ` [PATCH v2 08/13] mm/sparse: move __highest_used_section_nr handling Oscar Salvador (SUSE)
2026-09-21 19:59 ` [PATCH v2 09/13] scripts/gdb: mm.py: remove fallbacks for SECTION_HAS_MEM_MAP and SECTION_IS_EARLY David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 10/13] mm/sparse: remove SECTION_MARKED_PRESENT David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 11/13] mm/sparse: remove flags parameter from sparse_init_one_section() David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 12/13] fs/proc/page: clarify comment in get_max_dump_pfn() David Hildenbrand (Arm)
2026-09-21 19:59 ` [PATCH v2 13/13] mm/memory_hotplug: drop CONFIG_HAVE_ARCH_PFN_VALID handling from pfn_to_online_page() David Hildenbrand (Arm)
2026-09-22  4:25   ` Oscar Salvador (SUSE)
2026-09-21 22:53 ` [PATCH v2 00/13] mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups Andrew Morton

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