On 7/27/21 11:43 AM, Gavin Shan wrote:
> In debug_vm_pgtable(), there are many local variables introduced to
> track the needed information and they are passed to the functions for
> various test cases. It'd better to introduce a struct as place holder
> for these information. With it, what the tests functions need is the
> struct. In this way, the code is simplified and easier to be maintained.
>
> Besides, set_xxx_at() could access the data on the corresponding pages
> in the page table modifying tests. So the accessed pages in the tests
> should have been allocated from buddy. Otherwise, we're accessing pages
> that aren't owned by us. This causes issues like page flag corruption
> or kernel crash on accessing unmapped page when CONFIG_DEBUG_PAGEALLOC
> is enabled.
>
> This introduces "struct pgtable_debug_args". The struct is initialized
> and destroyed, but the information in the struct isn't used yet. It will
> be used in subsequent patches.
>
> Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> ---
> mm/debug_vm_pgtable.c | 280 +++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 279 insertions(+), 1 deletion(-)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 1c922691aa61..8c7361643166 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -58,6 +58,37 @@
> #define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK)
> #define RANDOM_NZVALUE GENMASK(7, 0)
>
> +struct pgtable_debug_args {
> + struct mm_struct *mm;
> + struct vm_area_struct *vma;
> +
> + pgd_t *pgdp;
> + p4d_t *p4dp;
> + pud_t *pudp;
> + pmd_t *pmdp;
> + pte_t *ptep;
> +
> + p4d_t *start_p4dp;
> + pud_t *start_pudp;
> + pmd_t *start_pmdp;
> + pgtable_t start_ptep;
> +
> + unsigned long vaddr;
> + pgprot_t page_prot;
> + pgprot_t page_prot_none;
> +
> + bool is_contiguous_page;
> + unsigned long pud_pfn;
> + unsigned long pmd_pfn;
> + unsigned long pte_pfn;
> +
> + unsigned long fixed_pgd_pfn;
> + unsigned long fixed_p4d_pfn;
> + unsigned long fixed_pud_pfn;
> + unsigned long fixed_pmd_pfn;
> + unsigned long fixed_pte_pfn;
> +};
> +
> static void __init pte_basic_tests(unsigned long pfn, int idx)
> {
> pgprot_t prot = protection_map[idx];
> @@ -955,8 +986,249 @@ static unsigned long __init get_random_vaddr(void)
> return random_vaddr;
> }
>
> +static void __init destroy_args(struct pgtable_debug_args *args)
> +{
> + struct page *page = NULL;
> +
> + /* Free (huge) page */
> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
> + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) &&
> + has_transparent_hugepage() &&
> + args->pud_pfn != ULONG_MAX) {
> + if (args->is_contiguous_page) {
> + free_contig_range(args->pud_pfn,
> + (1 << (HPAGE_PUD_SHIFT - PAGE_SHIFT)));
> + } else {
> + page = pfn_to_page(args->pud_pfn);
> + __free_pages(page, HPAGE_PUD_SHIFT - PAGE_SHIFT);
> + }
> +
> + args->pud_pfn = ULONG_MAX;
> + args->pmd_pfn = ULONG_MAX;
> + args->pte_pfn = ULONG_MAX;
> + }
> +
> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
> + has_transparent_hugepage() &&
> + args->pmd_pfn != ULONG_MAX) {
> + if (args->is_contiguous_page) {
> + free_contig_range(args->pmd_pfn, (1 << HPAGE_PMD_ORDER));
> + } else {
> + page = pfn_to_page(args->pmd_pfn);
> + __free_pages(page, HPAGE_PMD_ORDER);
> + }
> +
> + args->pmd_pfn = ULONG_MAX;
> + args->pte_pfn = ULONG_MAX;
> + }
> +
> + if (args->pte_pfn != ULONG_MAX) {
> + page = pfn_to_page(args->pte_pfn);
> + __free_pages(page, 0);
> + }
> +
> + /* Free page table entries */
> + if (args->start_ptep) {
> + pte_free(args->mm, args->start_ptep);
> + mm_dec_nr_ptes(args->mm);
> + }
> +
> + if (args->start_pmdp) {
> + pmd_free(args->mm, args->start_pmdp);
> + mm_dec_nr_pmds(args->mm);
> + }
> +
> + if (args->start_pudp) {
> + pud_free(args->mm, args->start_pudp);
> + mm_dec_nr_puds(args->mm);
> + }
> +
> + if (args->start_p4dp)
> + p4d_free(args->mm, args->p4dp);
^^^^ s/args->p4dp/args->start_p4dp ?
