The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x c3576889d87b603cb66b417e08844a53c1077a37 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025090629-cargo-udder-f24a@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From c3576889d87b603cb66b417e08844a53c1077a37 Mon Sep 17 00:00:00 2001 From: Sumanth Korikkar sumanthk@linux.ibm.com Date: Thu, 7 Aug 2025 20:35:45 +0200 Subject: [PATCH] mm: fix accounting of memmap pages
For !CONFIG_SPARSEMEM_VMEMMAP, memmap page accounting is currently done upfront in sparse_buffer_init(). However, sparse_buffer_alloc() may return NULL in failure scenario.
Also, memmap pages may be allocated either from the memblock allocator during early boot or from the buddy allocator. When removed via arch_remove_memory(), accounting of memmap pages must reflect the original allocation source.
To ensure correctness: * Account memmap pages after successful allocation in sparse_init_nid() and section_activate(). * Account memmap pages in section_deactivate() based on allocation source.
Link: https://lkml.kernel.org/r/20250807183545.1424509-1-sumanthk@linux.ibm.com Fixes: 15995a352474 ("mm: report per-page metadata information") Signed-off-by: Sumanth Korikkar sumanthk@linux.ibm.com Suggested-by: David Hildenbrand david@redhat.com Reviewed-by: Wei Yang richard.weiyang@gmail.com Cc: Alexander Gordeev agordeev@linux.ibm.com Cc: Gerald Schaefer gerald.schaefer@linux.ibm.com Cc: Heiko Carstens hca@linux.ibm.com Cc: Vasily Gorbik gor@linux.ibm.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index fd2ab5118e13..41aa0493eb03 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -578,11 +578,6 @@ struct page * __meminit __populate_section_memmap(unsigned long pfn, if (r < 0) return NULL;
- if (system_state == SYSTEM_BOOTING) - memmap_boot_pages_add(DIV_ROUND_UP(end - start, PAGE_SIZE)); - else - memmap_pages_add(DIV_ROUND_UP(end - start, PAGE_SIZE)); - return pfn_to_page(pfn); }
diff --git a/mm/sparse.c b/mm/sparse.c index 3c012cf83cc2..e6075b622407 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -454,9 +454,6 @@ static void __init sparse_buffer_init(unsigned long size, int nid) */ sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true); sparsemap_buf_end = sparsemap_buf + size; -#ifndef CONFIG_SPARSEMEM_VMEMMAP - memmap_boot_pages_add(DIV_ROUND_UP(size, PAGE_SIZE)); -#endif }
static void __init sparse_buffer_fini(void) @@ -567,6 +564,8 @@ static void __init sparse_init_nid(int nid, unsigned long pnum_begin, sparse_buffer_fini(); goto failed; } + memmap_boot_pages_add(DIV_ROUND_UP(PAGES_PER_SECTION * sizeof(struct page), + PAGE_SIZE)); sparse_init_early_section(nid, map, pnum, 0); } } @@ -680,7 +679,6 @@ static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages, unsigned long start = (unsigned long) pfn_to_page(pfn); unsigned long end = start + nr_pages * sizeof(struct page);
- memmap_pages_add(-1L * (DIV_ROUND_UP(end - start, PAGE_SIZE))); vmemmap_free(start, end, altmap); } static void free_map_bootmem(struct page *memmap) @@ -856,10 +854,14 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, * The memmap of early sections is always fully populated. See * section_activate() and pfn_valid() . */ - if (!section_is_early) + if (!section_is_early) { + memmap_pages_add(-1L * (DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE))); depopulate_section_memmap(pfn, nr_pages, altmap); - else if (memmap) + } else if (memmap) { + memmap_boot_pages_add(-1L * (DIV_ROUND_UP(nr_pages * sizeof(struct page), + PAGE_SIZE))); free_map_bootmem(memmap); + }
if (empty) ms->section_mem_map = (unsigned long)NULL; @@ -904,6 +906,7 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn, section_deactivate(pfn, nr_pages, altmap); return ERR_PTR(-ENOMEM); } + memmap_pages_add(DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE));
return memmap; }