Re: Fwd: [Bug 213069] New: kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:147! Oops: Exception in kernel mode, sig: 5 [#1]
From: Anshuman Khandual <hidden>
Date: 2021-05-17 12:51:46
Subsystem:
memory management, the rest · Maintainers:
Andrew Morton, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2021-05-14 · [Bug 213069] New: kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:147! Oops: Exception in kernel mode, sig: 5 [#1] · <hidden>
On 5/17/21 11:25 AM, Aneesh Kumar K.V wrote:
On 5/17/21 11:17 AM, Christophe Leroy wrote:quoted
+aneesh +linuxppc-dev list Le 17/05/2021 à 07:44, Anshuman Khandual a écrit :quoted
Hello Christophe, DEBUG_VM_PGTABLE has now been re-enabled on powerpc recently ? was not aware about this. From the error log, it failed explicitly on 4K page size hash config. static inline pmd_t hash__pmd_mkhuge(pmd_t pmd) { BUG(); ------> Failed return pmd; } static inline pmd_t __pmd_mkhuge(pmd_t pmd) { if (radix_enabled()) return radix__pmd_mkhuge(pmd); return hash__pmd_mkhuge(pmd); } pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot) { unsigned long pmdv; pmdv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK; return __pmd_mkhuge(pmd_set_protbits(__pmd(pmdv), pgprot)); } It seems like on powerpc, where pfn_pmd() makes a huge page but which is not supported on 4K hash config thus triggering the BUG(). But all pfn_pmd() call sites inside the debug_vm_pgtable() test are protected with CONFIG_TRANSPARENT_HUGEPAGE. IIUC unlike powerpc, pfn_pmd() does not directly make a huge page on other platforms. Looking at arch/powerpc/include/asm/book3s/64/hash-4k.h, all relevant THP helpers has BUG() or 0 which indicates THP might not be supported on 4K page size hash config ? But looking at arch/powerpc/platforms/Kconfig.cputype, it seems like HAVE_ARCH_TRANSPARENT_HUGEPAGE is invariably selected on PPC_BOOK3S_64 platforms which I assume includes 4K page size hash config as well. Is THP some how getting enabled on this 4K page size hash config where it should not be (thus triggering the BUG) ? OR am I missing something here.We should put those pfn_pmd() and pfn_pud() after if (!has_transparent_hugepage()) return;
The following patch has been lightly tested on arm64 and x86 platforms. Could you please verify if this solves the problem on powerpc 4K hash config ? Thank you. - Anshuman mm/debug_vm_pgtable.c | 58 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 48 insertions(+), 10 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index e2f35db8ba69..6ff92c8b0a00 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
@@ -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. */
@@ -244,12 +250,16 @@ static void __init pmd_leaf_tests(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)))); }
@@ -258,13 +268,14 @@ 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
@@ -348,9 +359,13 @@ 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. */
@@ -642,12 +657,16 @@ 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)); }
@@ -667,18 +686,26 @@ 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 */
@@ -721,25 +748,33 @@ 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))); }
@@ -768,6 +803,9 @@ 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