We add pmd folio into ds_queue on the first page fault in __do_huge_pmd_anonymous_page(), so that we can split it in case of memory pressure. This should be the same for a pmd folio during wp page fault.

Commit 1ced09e0331f ("mm: allocate THP on hugezeropage wp-fault") miss to add it to ds_queue, which means system may not reclaim enough memory in case of memory pressure even the pmd folio is under used.

Move deferred_split_folio() into map_anon_folio_pmd() to make the pmd folio installation consistent.

Fixes: 1ced09e0331f ("mm: allocate THP on hugezeropage wp-fault") Signed-off-by: Wei Yang richard.weiyang@gmail.com Cc: David Hildenbrand david@redhat.com Cc: Lance Yang lance.yang@linux.dev Cc: Dev Jain dev.jain@arm.com Acked-by: David Hildenbrand david@redhat.com Reviewed-by: Lance Yang lance.yang@linux.dev Reviewed-by: Dev Jain dev.jain@arm.com Acked-by: Usama Arif usamaarif642@gmail.com Reviewed-by: Zi Yan ziy@nvidia.com Cc: stable@vger.kernel.org

--- v3: * rebase on latest mm-new * gather rb and acked-by v2: * add fix, cc stable and put description about the flow of current code * move deferred_split_folio() into map_anon_folio_pmd() --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 002922bb6e42..e86699306c5e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1317,6 +1317,7 @@ static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd, count_vm_event(THP_FAULT_ALLOC); count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); + deferred_split_folio(folio, false); }

static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) @@ -1357,7 +1358,6 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); map_anon_folio_pmd(folio, vmf->pmd, vma, haddr); mm_inc_nr_ptes(vma->vm_mm); - deferred_split_folio(folio, false); spin_unlock(vmf->ptl); }