On Fri, Dec 17, 2021 at 3:33 AM David Hildenbrand david@redhat.com wrote:
Let's consolidate the mapcount logic to make it easier to understand and to prepare for further changes.
Reviewed-by: Peter Xu peterx@redhat.com Signed-off-by: David Hildenbrand david@redhat.com
Reviewed-by: Yang Shi shy828301@gmail.com
mm/huge_memory.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e5483347291c..4751d03947da 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2101,21 +2101,25 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pte = pte_offset_map(&_pmd, addr); BUG_ON(!pte_none(*pte)); set_pte_at(mm, addr, pte, entry);
if (!pmd_migration)atomic_inc(&page[i]._mapcount); pte_unmap(pte); } if (!pmd_migration) {
/* Sub-page mapcount accounting for above small mappings. */int val = 1;/* * Set PG_double_map before dropping compound_mapcount to avoid * false-negative page_mapped().** The first to set PageDoubleMap() has to increment all* sub-page mapcounts by one. */
if (compound_mapcount(page) > 1 &&!TestSetPageDoubleMap(page)) {for (i = 0; i < HPAGE_PMD_NR; i++)atomic_inc(&page[i]._mapcount);}
if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page))val++;for (i = 0; i < HPAGE_PMD_NR; i++)atomic_add(val, &page[i]._mapcount); lock_page_memcg(page); if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {-- 2.31.1