Commit 1bcdb769 authored by Baolin Wang's avatar Baolin Wang Committed by Andrew Morton
Browse files

arm64/hugetlb: implement arm64 specific hugetlb_mask_last_page 

The HugeTLB address ranges are linearly scanned during fork, unmap and
remap operations, and the linear scan can skip to the end of range mapped
by the page table page if hitting a non-present entry, which can help to
speed linear scanning of the HugeTLB address ranges.

So hugetlb_mask_last_page() is introduced to help to update the address in
the loop of HugeTLB linear scanning with getting the last huge page mapped
by the associated page table page[1], when a non-present entry is
encountered.

Considering ARM64 specific cont-pte/pmd size HugeTLB, this patch
implemented an ARM64 specific hugetlb_mask_last_page() to help this case.

[1] https://lore.kernel.org/linux-mm/20220527225849.284839-1-mike.kravetz@oracle.com/

[baolin.wang@linux.alibaba.com: fix build]
  Link: https://lkml.kernel.org/r/a14e7b39-6a8a-4609-b4a1-84ac574f5c96@linux.alibaba.com
Link: https://lkml.kernel.org/r/20220621235620.291305-3-mike.kravetz@oracle.com


Signed-off-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Acked-by: default avatarMuchun Song <songmuchun@bytedance.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent e95a9851

arch/arm64/mm/hugetlbpage.c

+22 −0
Original line number Diff line number Diff line
@@ -368,6 +368,28 @@ pte_t *huge_pte_offset(struct mm_struct *mm, 
	return NULL;

}



unsigned long hugetlb_mask_last_page(struct hstate *h)

{

	unsigned long hp_size = huge_page_size(h);



	switch (hp_size) {

#ifndef __PAGETABLE_PMD_FOLDED

	case PUD_SIZE:

		return PGDIR_SIZE - PUD_SIZE;

#endif

	case CONT_PMD_SIZE:

		return PUD_SIZE - CONT_PMD_SIZE;

	case PMD_SIZE:

		return PUD_SIZE - PMD_SIZE;

	case CONT_PTE_SIZE:

		return PMD_SIZE - CONT_PTE_SIZE;

	default:

		break;

	}



	return 0UL;

}



pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)

{

	size_t pagesize = 1UL << shift;