Re: [PATCH v2 00/13] mm/debug_vm_pgtable fixes

"Aneesh Kumar K.V" [off-list ref] writes:

This patch series includes fixes for debug_vm_pgtable test code so that
they follow page table updates rules correctly. The first two patches introduce
changes w.r.t ppc64. The patches are included in this series for completeness. We can
merge them via ppc64 tree if required.

Hugetlb test is disabled on ppc64 because that needs larger change to satisfy
page table update rules.

Changes from V1:
* Address review feedback
* drop test specific pfn_pte and pfn_pmd.
* Update ppc64 page table helper to add _PAGE_PTE 

Aneesh Kumar K.V (13):
  powerpc/mm: Add DEBUG_VM WARN for pmd_clear
  powerpc/mm: Move setting pte specific flags to pfn_pte
  mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value
  mm/debug_vm_pgtables/hugevmap: Use the arch helper to identify huge
    vmap support.
  mm/debug_vm_pgtable/savedwrite: Enable savedwrite test with
    CONFIG_NUMA_BALANCING
  mm/debug_vm_pgtable/THP: Mark the pte entry huge before using
    set_pmd/pud_at
  mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an
    existing pte entry
  mm/debug_vm_pgtable/thp: Use page table depost/withdraw with THP
  mm/debug_vm_pgtable/locks: Move non page table modifying test together
  mm/debug_vm_pgtable/locks: Take correct page table lock
  mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries
  mm/debug_vm_pgtable/hugetlb: Disable hugetlb test on ppc64
  mm/debug_vm_pgtable: populate a pte entry before fetching it

 arch/powerpc/include/asm/book3s/64/pgtable.h |  29 +++-
 arch/powerpc/include/asm/nohash/pgtable.h    |   5 -
 arch/powerpc/mm/book3s64/pgtable.c           |   2 +-
 arch/powerpc/mm/pgtable.c                    |   5 -
 include/linux/io.h                           |  12 ++
 mm/debug_vm_pgtable.c                        | 151 +++++++++++--------
 6 files changed, 127 insertions(+), 77 deletions(-)

BTW I picked a wrong branch when sending this. Attaching the diff
against what I want to send.  pfn_pmd() no more updates _PAGE_PTE
because that is handled by pmd_mkhuge().

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 3b4da7c63e28..e18ae50a275c 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c

@@ -141,7 +141,7 @@ pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
 	unsigned long pmdv;
 
 	pmdv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK;
-	return __pmd(pmdv | pgprot_val(pgprot) | _PAGE_PTE);
+	return pmd_set_protbits(__pmd(pmdv), pgprot);
 }
 
 pmd_t mk_pmd(struct page *page, pgprot_t pgprot)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 7d9f8e1d790f..cad61d22f33a 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c

@@ -229,7 +229,7 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
 
 static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
 
 	if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
 		return;