Commit c3576889 authored by Sumanth Korikkar's avatar Sumanth Korikkar Committed by Andrew Morton
Browse files

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: 15995a35 ("mm: report per-page metadata information")
Signed-off-by: default avatarSumanth Korikkar <sumanthk@linux.ibm.com>
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarWei 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 9f68eaba

mm/sparse-vmemmap.c

+0 −5
Original line number Diff line number Diff line
@@ -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);

}

mm/sparse.c

+9 −6
Original line number Diff line number Diff line
@@ -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;

}