6.18-stable review patch. If anyone has any objections, please let me know.
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From: Wei Yang richard.weiyang@gmail.com
commit 2a1351cd4176ee1809b0900d386919d03b7652f8 upstream.
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.
Link: https://lkml.kernel.org/r/20251008095453.18772-2-richard.weiyang@gmail.com Fixes: 1ced09e0331f ("mm: allocate THP on hugezeropage wp-fault") Signed-off-by: Wei Yang richard.weiyang@gmail.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 Reviewed-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: Matthew Wilcox willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1233,6 +1233,7 @@ static void map_anon_folio_pmd(struct fo 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) @@ -1273,7 +1274,6 @@ static vm_fault_t __do_huge_pmd_anonymou 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); }