From 7da4e2cb8b1ff8221759bfc7512d651ee69516dc Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Thu, 16 Jun 2022 10:48:38 -0700 Subject: [PATCH] mm: thp: kill __transhuge_page_enabled() The page fault path checks THP eligibility with __transhuge_page_enabled() which does the similar thing as hugepage_vma_check(), so use hugepage_vma_check() instead. However page fault allows DAX and !anon_vma cases, so added a new flag, in_pf, to hugepage_vma_check() to make page fault work correctly. The in_pf flag is also used to skip shmem and file THP for page fault since shmem handles THP in its own shmem_fault() and file THP allocation on fault is not supported yet. Also remove hugepage_vma_enabled() since hugepage_vma_check() is the only caller now, it is not necessary to have a helper function. Link: https://lkml.kernel.org/r/20220616174840.1202070-6-shy828301@gmail.com Signed-off-by: Yang Shi Reviewed-by: Zach O'Keefe Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- fs/proc/task_mmu.c | 2 +- include/linux/huge_mm.h | 57 ++----------------------------------------------- mm/huge_memory.c | 51 +++++++++++++++++++++++++++++++++---------- mm/khugepaged.c | 8 +++---- mm/memory.c | 7 ++++-- 5 files changed, 52 insertions(+), 73 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 072cf77..a3398d0 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -863,7 +863,7 @@ static int show_smap(struct seq_file *m, void *v) __show_smap(m, &mss, false); seq_printf(m, "THPeligible: %d\n", - hugepage_vma_check(vma, vma->vm_flags, true)); + hugepage_vma_check(vma, vma->vm_flags, true, false)); if (arch_pkeys_enabled()) seq_printf(m, "ProtectionKey: %8u\n", vma_pkey(vma)); diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 64487bc..cd8a6c5 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -146,48 +146,6 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, return true; } -static inline bool transhuge_vma_enabled(struct vm_area_struct *vma, - unsigned long vm_flags) -{ - /* Explicitly disabled through madvise. */ - if ((vm_flags & VM_NOHUGEPAGE) || - test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) - return false; - return true; -} - -/* - * to be used on vmas which are known to support THP. - * Use transparent_hugepage_active otherwise - */ -static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma) -{ - - /* - * If the hardware/firmware marked hugepage support disabled. - */ - if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX)) - return false; - - if (!transhuge_vma_enabled(vma, vma->vm_flags)) - return false; - - if (vma_is_temporary_stack(vma)) - return false; - - if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG)) - return true; - - if (vma_is_dax(vma)) - return true; - - if (transparent_hugepage_flags & - (1 << TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)) - return !!(vma->vm_flags & VM_HUGEPAGE); - - return false; -} - static inline bool file_thp_enabled(struct vm_area_struct *vma) { struct inode *inode; @@ -204,7 +162,7 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma) bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, - bool smaps); + bool smaps, bool in_pf); #define transparent_hugepage_use_zero_page() \ (transparent_hugepage_flags & \ @@ -348,26 +306,15 @@ static inline bool folio_test_pmd_mappable(struct folio *folio) return false; } -static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma) -{ - return false; -} - static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, unsigned long addr) { return false; } -static inline bool transhuge_vma_enabled(struct vm_area_struct *vma, - unsigned long vm_flags) -{ - return false; -} - static inline bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, - bool smaps) + bool smaps, bool in_pf) { return false; } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8cbd21a..4b90c70 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -71,27 +71,53 @@ unsigned long huge_zero_pfn __read_mostly = ~0UL; bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, - bool smaps) + bool smaps, bool in_pf) { if (!vma->vm_mm) /* vdso */ return false; - if (!transhuge_vma_enabled(vma, vm_flags)) + /* + * Explicitly disabled through madvise or prctl, or some + * architectures may disable THP for some mappings, for + * example, s390 kvm. + * */ + if ((vm_flags & VM_NOHUGEPAGE) || + test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) return false; - - if (vm_flags & VM_NO_KHUGEPAGED) + /* + * If the hardware/firmware marked hugepage support disabled. + */ + if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX)) return false; - /* Don't run khugepaged against DAX vma */ + /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ if (vma_is_dax(vma)) + return in_pf; + + /* + * Special VMA and hugetlb VMA. + * Must be checked after dax since some dax mappings may have + * VM_MIXEDMAP set. + */ + if (vm_flags & VM_NO_KHUGEPAGED) return false; - /* Check alignment for file vma and size for both file and anon vma */ - if (!transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) + /* + * Check alignment for file vma and size for both file and anon vma. + * + * Skip the check for page fault. Huge fault does the check in fault + * handlers. And this check is not suitable for huge PUD fault. + */ + if (!in_pf && + !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) return false; - /* Enabled via shmem mount options or sysfs settings. */ - if (shmem_file(vma->vm_file)) + /* + * Enabled via shmem mount options or sysfs settings. + * Must be done before hugepage flags check since shmem has its + * own flags. + */ + if (!in_pf && shmem_file(vma->vm_file)) return shmem_huge_enabled(vma); if (!khugepaged_enabled()) @@ -102,7 +128,7 @@ bool hugepage_vma_check(struct vm_area_struct *vma, return false; /* Only regular file is valid */ - if (file_thp_enabled(vma)) + if (!in_pf && file_thp_enabled(vma)) return true; if (!vma_is_anonymous(vma)) @@ -114,9 +140,12 @@ bool hugepage_vma_check(struct vm_area_struct *vma, /* * THPeligible bit of smaps should show 1 for proper VMAs even * though anon_vma is not initialized yet. + * + * Allow page fault since anon_vma may be not initialized until + * the first page fault. */ if (!vma->anon_vma) - return smaps; + return (smaps || in_pf); return true; } diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 6bbf3ad..d683ef1 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -466,7 +466,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma, { if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) && khugepaged_enabled()) { - if (hugepage_vma_check(vma, vm_flags, false)) + if (hugepage_vma_check(vma, vm_flags, false, false)) __khugepaged_enter(vma->vm_mm); } } @@ -916,7 +916,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, if (!transhuge_vma_suitable(vma, address)) return SCAN_ADDRESS_RANGE; - if (!hugepage_vma_check(vma, vma->vm_flags, false)) + if (!hugepage_vma_check(vma, vma->vm_flags, false, false)) return SCAN_VMA_CHECK; /* * Anon VMA expected, the address may be unmapped then @@ -1401,7 +1401,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() * will not fail the vma for missing VM_HUGEPAGE */ - if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false)) + if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false, false)) return; /* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */ @@ -2091,7 +2091,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, progress++; break; } - if (!hugepage_vma_check(vma, vma->vm_flags, false)) { + if (!hugepage_vma_check(vma, vma->vm_flags, false, false)) { skip: progress++; continue; diff --git a/mm/memory.c b/mm/memory.c index dce0b2e..2392d5d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4970,6 +4970,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, .gfp_mask = __get_fault_gfp_mask(vma), }; struct mm_struct *mm = vma->vm_mm; + unsigned long vm_flags = vma->vm_flags; pgd_t *pgd; p4d_t *p4d; vm_fault_t ret; @@ -4983,7 +4984,8 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, if (!vmf.pud) return VM_FAULT_OOM; retry_pud: - if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) { + if (pud_none(*vmf.pud) && + hugepage_vma_check(vma, vm_flags, false, true)) { ret = create_huge_pud(&vmf); if (!(ret & VM_FAULT_FALLBACK)) return ret; @@ -5016,7 +5018,8 @@ retry_pud: if (pud_trans_unstable(vmf.pud)) goto retry_pud; - if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) { + if (pmd_none(*vmf.pmd) && + hugepage_vma_check(vma, vm_flags, false, true)) { ret = create_huge_pmd(&vmf); if (!(ret & VM_FAULT_FALLBACK)) return ret; -- 2.7.4