From 882fe4ff1cb97108be8a3354c4cdbf3d2a8d56a6 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Wed, 7 Jul 2021 18:10:06 -0700 Subject: [PATCH] mm/mremap: convert huge PUD move to separate helper With TRANSPARENT_HUGEPAGE_PUD enabled the kernel can find huge PUD entries. Add a helper to move huge PUD entries on mremap(). This will be used by a later patch to optimize mremap of PUD_SIZE aligned level 4 PTE mapped address This also make sure we support mremap on huge PUD entries even with CONFIG_HAVE_MOVE_PUD disabled. [aneesh.kumar@linux.ibm.com: fix build failure with clang-10] Link: https://lore.kernel.org/lkml/YMuOSnJsL9qkxweY@archlinux-ax161 Link: https://lkml.kernel.org/r/20210619134310.89098-1-aneesh.kumar@linux.ibm.com Link: https://lkml.kernel.org/r/20210616045239.370802-4-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V Cc: Christophe Leroy Cc: Hugh Dickins Cc: Joel Fernandes Cc: Kalesh Singh Cc: Kirill A. Shutemov Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mremap.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 73 insertions(+), 7 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index a369a6100698b..4bcaf17424c88 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -324,10 +324,61 @@ static inline bool move_normal_pud(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +static bool move_huge_pud(struct vm_area_struct *vma, unsigned long old_addr, + unsigned long new_addr, pud_t *old_pud, pud_t *new_pud) +{ + spinlock_t *old_ptl, *new_ptl; + struct mm_struct *mm = vma->vm_mm; + pud_t pud; + + /* + * The destination pud shouldn't be established, free_pgtables() + * should have released it. + */ + if (WARN_ON_ONCE(!pud_none(*new_pud))) + return false; + + /* + * We don't have to worry about the ordering of src and dst + * ptlocks because exclusive mmap_lock prevents deadlock. + */ + old_ptl = pud_lock(vma->vm_mm, old_pud); + new_ptl = pud_lockptr(mm, new_pud); + if (new_ptl != old_ptl) + spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); + + /* Clear the pud */ + pud = *old_pud; + pud_clear(old_pud); + + VM_BUG_ON(!pud_none(*new_pud)); + + /* Set the new pud */ + /* mark soft_ditry when we add pud level soft dirty support */ + set_pud_at(mm, new_addr, new_pud, pud); + flush_pud_tlb_range(vma, old_addr, old_addr + HPAGE_PUD_SIZE); + if (new_ptl != old_ptl) + spin_unlock(new_ptl); + spin_unlock(old_ptl); + + return true; +} +#else +static bool move_huge_pud(struct vm_area_struct *vma, unsigned long old_addr, + unsigned long new_addr, pud_t *old_pud, pud_t *new_pud) +{ + WARN_ON_ONCE(1); + return false; + +} +#endif + enum pgt_entry { NORMAL_PMD, HPAGE_PMD, NORMAL_PUD, + HPAGE_PUD, }; /* @@ -347,6 +398,7 @@ static __always_inline unsigned long get_extent(enum pgt_entry entry, mask = PMD_MASK; size = PMD_SIZE; break; + case HPAGE_PUD: case NORMAL_PUD: mask = PUD_MASK; size = PUD_SIZE; @@ -395,6 +447,12 @@ static bool move_pgt_entry(enum pgt_entry entry, struct vm_area_struct *vma, move_huge_pmd(vma, old_addr, new_addr, old_entry, new_entry); break; + case HPAGE_PUD: + moved = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + move_huge_pud(vma, old_addr, new_addr, old_entry, + new_entry); + break; + default: WARN_ON_ONCE(1); break; @@ -414,6 +472,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long extent, old_end; struct mmu_notifier_range range; pmd_t *old_pmd, *new_pmd; + pud_t *old_pud, *new_pud; old_end = old_addr + len; flush_cache_range(vma, old_addr, old_end); @@ -429,15 +488,22 @@ unsigned long move_page_tables(struct vm_area_struct *vma, * PUD level if possible. */ extent = get_extent(NORMAL_PUD, old_addr, old_end, new_addr); - if (IS_ENABLED(CONFIG_HAVE_MOVE_PUD) && extent == PUD_SIZE) { - pud_t *old_pud, *new_pud; - old_pud = get_old_pud(vma->vm_mm, old_addr); - if (!old_pud) + old_pud = get_old_pud(vma->vm_mm, old_addr); + if (!old_pud) + continue; + new_pud = alloc_new_pud(vma->vm_mm, vma, new_addr); + if (!new_pud) + break; + if (pud_trans_huge(*old_pud) || pud_devmap(*old_pud)) { + if (extent == HPAGE_PUD_SIZE) { + move_pgt_entry(HPAGE_PUD, vma, old_addr, new_addr, + old_pud, new_pud, need_rmap_locks); + /* We ignore and continue on error? */ continue; - new_pud = alloc_new_pud(vma->vm_mm, vma, new_addr); - if (!new_pud) - break; + } + } else if (IS_ENABLED(CONFIG_HAVE_MOVE_PUD) && extent == PUD_SIZE) { + if (move_pgt_entry(NORMAL_PUD, vma, old_addr, new_addr, old_pud, new_pud, need_rmap_locks)) continue; -- 2.39.5