On certain platforms, THP support could not just be validated via the build option CONFIG_TRANSPARENT_HUGEPAGE. Instead has_transparent_hugepage() also needs to be called upon to verify THP runtime support. Otherwise the debug test will just run into unusable THP helpers like in the case of a 4K hash config on powerpc platform [1]. This just moves all pfn_pmd() and pfn_pud() after THP runtime validation with has_transparent_hugepage() which prevents the mentioned problem. [1] https://bugzilla.kernel.org/show_bug.cgi?id=213069 Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: linux-mm@xxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Fixes: 787d563b8642 ("mm/debug_vm_pgtable: fix kernel crash by checking for THP support") Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> --- This applies on v5.13-rc2. Changes in V2: - Updated [pmd|pud]_advanced_tests() per Christophe - Added "Fixes: " tag per Christophe Changes in V1: https://lore.kernel.org/linux-mm/1621325590-18199-1-git-send-email-anshuman.khandual@xxxxxxx/ mm/debug_vm_pgtable.c | 63 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 51 insertions(+), 12 deletions(-) diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 05efe98a9ac2..b3c7e7b04cb9 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -146,13 +146,14 @@ static void __init pte_savedwrite_tests(unsigned long pfn, pgprot_t prot) static void __init pmd_basic_tests(unsigned long pfn, int idx) { pgprot_t prot = protection_map[idx]; - pmd_t pmd = pfn_pmd(pfn, prot); unsigned long val = idx, *ptr = &val; + pmd_t pmd; if (!has_transparent_hugepage()) return; pr_debug("Validating PMD basic (%pGv)\n", ptr); + pmd = pfn_pmd(pfn, prot); /* * This test needs to be executed after the given page table entry @@ -185,7 +186,7 @@ static void __init pmd_advanced_tests(struct mm_struct *mm, unsigned long pfn, unsigned long vaddr, pgprot_t prot, pgtable_t pgtable) { - pmd_t pmd = pfn_pmd(pfn, prot); + pmd_t pmd; if (!has_transparent_hugepage()) return; @@ -232,9 +233,14 @@ static void __init pmd_advanced_tests(struct mm_struct *mm, static void __init pmd_leaf_tests(unsigned long pfn, pgprot_t prot) { - pmd_t pmd = pfn_pmd(pfn, prot); + pmd_t pmd; + + if (!has_transparent_hugepage()) + return; pr_debug("Validating PMD leaf\n"); + pmd = pfn_pmd(pfn, prot); + /* * PMD based THP is a leaf entry. */ @@ -267,12 +273,16 @@ 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; if (!IS_ENABLED(CONFIG_NUMA_BALANCING)) return; + if (!has_transparent_hugepage()) + return; + pr_debug("Validating PMD saved write\n"); + pmd = pfn_pmd(pfn, prot); WARN_ON(!pmd_savedwrite(pmd_mk_savedwrite(pmd_clear_savedwrite(pmd)))); WARN_ON(pmd_savedwrite(pmd_clear_savedwrite(pmd_mk_savedwrite(pmd)))); } @@ -281,13 +291,14 @@ static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot) static void __init pud_basic_tests(struct mm_struct *mm, unsigned long pfn, int idx) { pgprot_t prot = protection_map[idx]; - pud_t pud = pfn_pud(pfn, prot); unsigned long val = idx, *ptr = &val; + pud_t pud; if (!has_transparent_hugepage()) return; pr_debug("Validating PUD basic (%pGv)\n", ptr); + pud = pfn_pud(pfn, prot); /* * This test needs to be executed after the given page table entry @@ -323,7 +334,7 @@ static void __init pud_advanced_tests(struct mm_struct *mm, unsigned long pfn, unsigned long vaddr, pgprot_t prot) { - pud_t pud = pfn_pud(pfn, prot); + pud_t pud; if (!has_transparent_hugepage()) return; @@ -332,6 +343,7 @@ static void __init pud_advanced_tests(struct mm_struct *mm, /* Align the address wrt HPAGE_PUD_SIZE */ vaddr = (vaddr & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE; + pud = pfn_pud(pfn, prot); set_pud_at(mm, vaddr, pudp, pud); pudp_set_wrprotect(mm, vaddr, pudp); pud = READ_ONCE(*pudp); @@ -370,9 +382,13 @@ static void __init pud_advanced_tests(struct mm_struct *mm, static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot) { - pud_t pud = pfn_pud(pfn, prot); + pud_t pud; + + if (!has_transparent_hugepage()) + return; pr_debug("Validating PUD leaf\n"); + pud = pfn_pud(pfn, prot); /* * PUD based THP is a leaf entry. */ @@ -654,12 +670,16 @@ static void __init pte_protnone_tests(unsigned long pfn, pgprot_t prot) #ifdef CONFIG_TRANSPARENT_HUGEPAGE static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t prot) { - pmd_t pmd = pmd_mkhuge(pfn_pmd(pfn, prot)); + pmd_t pmd; if (!IS_ENABLED(CONFIG_NUMA_BALANCING)) return; + if (!has_transparent_hugepage()) + return; + pr_debug("Validating PMD protnone\n"); + pmd = pmd_mkhuge(pfn_pmd(pfn, prot)); WARN_ON(!pmd_protnone(pmd)); WARN_ON(!pmd_present(pmd)); } @@ -679,18 +699,26 @@ static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot) #ifdef CONFIG_TRANSPARENT_HUGEPAGE static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot) { - pmd_t pmd = pfn_pmd(pfn, prot); + pmd_t pmd; + + if (!has_transparent_hugepage()) + return; pr_debug("Validating PMD devmap\n"); + pmd = pfn_pmd(pfn, prot); WARN_ON(!pmd_devmap(pmd_mkdevmap(pmd))); } #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot) { - pud_t pud = pfn_pud(pfn, prot); + pud_t pud; + + if (!has_transparent_hugepage()) + return; pr_debug("Validating PUD devmap\n"); + pud = pfn_pud(pfn, prot); WARN_ON(!pud_devmap(pud_mkdevmap(pud))); } #else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ @@ -733,25 +761,33 @@ static void __init pte_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot) #ifdef CONFIG_TRANSPARENT_HUGEPAGE static void __init pmd_soft_dirty_tests(unsigned long pfn, pgprot_t prot) { - pmd_t pmd = pfn_pmd(pfn, prot); + pmd_t pmd; if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)) return; + if (!has_transparent_hugepage()) + return; + pr_debug("Validating PMD soft dirty\n"); + pmd = pfn_pmd(pfn, prot); WARN_ON(!pmd_soft_dirty(pmd_mksoft_dirty(pmd))); WARN_ON(pmd_soft_dirty(pmd_clear_soft_dirty(pmd))); } static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot) { - pmd_t pmd = pfn_pmd(pfn, prot); + pmd_t pmd; if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) || !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION)) return; + if (!has_transparent_hugepage()) + return; + pr_debug("Validating PMD swap soft dirty\n"); + pmd = pfn_pmd(pfn, prot); WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd))); WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd))); } @@ -780,6 +816,9 @@ static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot) swp_entry_t swp; pmd_t pmd; + if (!has_transparent_hugepage()) + return; + pr_debug("Validating PMD swap\n"); pmd = pfn_pmd(pfn, prot); swp = __pmd_to_swp_entry(pmd); -- 2.20.1
