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mm: fix accounting of memmap pages

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[ Upstream commit c3576889d8 ]

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: 15995a3524 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sumanth Korikkar 2025-09-06 21:44:36 -04:00 committed by Greg Kroah-Hartman
parent a7f7d4223f
commit 1ee0e14814
2 changed files with 9 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
mm/sparse-vmemmap.c
View File

@ -474,10 +474,5 @@ 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);
}

15
mm/sparse.c
View File

@ -462,9 +462,6 @@ 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)
@ -532,6 +529,8 @@ 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));
check_usemap_section_nr(nid, usage);
sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
SECTION_IS_EARLY);
@ -643,7 +642,6 @@ 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)
@ -819,10 +817,14 @@ 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;
@ -867,6 +869,7 @@ 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;
}