diff options
| -rw-r--r-- | include/linux/hugetlb.h | 14 | ||||
| -rw-r--r-- | include/linux/mm.h | 6 | ||||
| -rw-r--r-- | mm/hugetlb.c | 37 | ||||
| -rw-r--r-- | mm/rmap.c | 56 |
4 files changed, 111 insertions, 2 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 48c76d612d40..b699d59d0f4f 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -109,6 +109,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz); pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr); int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep); +void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma, + unsigned long *start, unsigned long *end); struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, int write); struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, @@ -131,6 +133,18 @@ static inline unsigned long hugetlb_total_pages(void) return 0; } +static inline int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, + pte_t *ptep) +{ + return 0; +} + +static inline void adjust_range_if_pmd_sharing_possible( + struct vm_area_struct *vma, + unsigned long *start, unsigned long *end) +{ +} + #define follow_hugetlb_page(m,v,p,vs,a,b,i,w) ({ BUG(); 0; }) #define follow_huge_addr(mm, addr, write) ERR_PTR(-EINVAL) #define copy_hugetlb_page_range(src, dst, vma) ({ BUG(); 0; }) diff --git a/include/linux/mm.h b/include/linux/mm.h index 493d07931ea5..11a5a46ce72b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2187,6 +2187,12 @@ static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm, return vma; } +static inline bool range_in_vma(struct vm_area_struct *vma, + unsigned long start, unsigned long end) +{ + return (vma && vma->vm_start <= start && end <= vma->vm_end); +} + #ifdef CONFIG_MMU pgprot_t vm_get_page_prot(unsigned long vm_flags); void vma_set_page_prot(struct vm_area_struct *vma); diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 7bd390797092..5e3a4db36310 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4333,13 +4333,41 @@ static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr) /* * check on proper vm_flags and page table alignment */ - if (vma->vm_flags & VM_MAYSHARE && - vma->vm_start <= base && end <= vma->vm_end) + if (vma->vm_flags & VM_MAYSHARE && range_in_vma(vma, base, end)) return true; return false; } /* + * Determine if start,end range within vma could be mapped by shared pmd. + * If yes, adjust start and end to cover range associated with possible + * shared pmd mappings. + */ +void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma, + unsigned long *start, unsigned long *end) +{ + unsigned long check_addr = *start; + + if (!(vma->vm_flags & VM_MAYSHARE)) + return; + + for (check_addr = *start; check_addr < *end; check_addr += PUD_SIZE) { + unsigned long a_start = check_addr & PUD_MASK; + unsigned long a_end = a_start + PUD_SIZE; + + /* + * If sharing is possible, adjust start/end if necessary. + */ + if (range_in_vma(vma, a_start, a_end)) { + if (a_start < *start) + *start = a_start; + if (a_end > *end) + *end = a_end; + } + } +} + +/* * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc() * and returns the corresponding pte. While this is not necessary for the * !shared pmd case because we can allocate the pmd later as well, it makes the @@ -4435,6 +4463,11 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) { return 0; } + +void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma, + unsigned long *start, unsigned long *end) +{ +} #define want_pmd_share() (0) #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ diff --git a/mm/rmap.c b/mm/rmap.c index 94488b0362f8..a7276d8c96f3 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1476,6 +1476,9 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, pte_t pteval; spinlock_t *ptl; int ret = SWAP_AGAIN; + unsigned long sh_address; + bool pmd_sharing_possible = false; + unsigned long spmd_start, spmd_end; struct rmap_private *rp = arg; enum ttu_flags flags = rp->flags; @@ -1491,6 +1494,32 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, goto out; } + /* + * Only use the range_start/end mmu notifiers if huge pmd sharing + * is possible. In the normal case, mmu_notifier_invalidate_page + * is sufficient as we only unmap a page. However, if we unshare + * a pmd, we will unmap a PUD_SIZE range. + */ + if (PageHuge(page)) { + spmd_start = address; + spmd_end = spmd_start + vma_mmu_pagesize(vma); + + /* + * Check if pmd sharing is possible. If possible, we could + * unmap a PUD_SIZE range. spmd_start/spmd_end will be + * modified if sharing is possible. + */ + adjust_range_if_pmd_sharing_possible(vma, &spmd_start, + &spmd_end); + if (spmd_end - spmd_start != vma_mmu_pagesize(vma)) { + sh_address = address; + + pmd_sharing_possible = true; + mmu_notifier_invalidate_range_start(vma->vm_mm, + spmd_start, spmd_end); + } + } + pte = page_check_address(page, mm, address, &ptl, PageTransCompound(page)); if (!pte) @@ -1524,6 +1553,30 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, } } + /* + * Call huge_pmd_unshare to potentially unshare a huge pmd. Pass + * sh_address as it will be modified if unsharing is successful. + */ + if (PageHuge(page) && huge_pmd_unshare(mm, &sh_address, pte)) { + /* + * huge_pmd_unshare unmapped an entire PMD page. There is + * no way of knowing exactly which PMDs may be cached for + * this mm, so flush them all. spmd_start/spmd_end cover + * this PUD_SIZE range. + */ + flush_cache_range(vma, spmd_start, spmd_end); + flush_tlb_range(vma, spmd_start, spmd_end); + + /* + * The ref count of the PMD page was dropped which is part + * of the way map counting is done for shared PMDs. When + * there is no other sharing, huge_pmd_unshare returns false + * and we will unmap the actual page and drop map count + * to zero. + */ + goto out_unmap; + } + /* Nuke the page table entry. */ flush_cache_page(vma, address, page_to_pfn(page)); if (should_defer_flush(mm, flags)) { @@ -1621,6 +1674,9 @@ out_unmap: if (ret != SWAP_FAIL && ret != SWAP_MLOCK && !(flags & TTU_MUNLOCK)) mmu_notifier_invalidate_page(mm, address); out: + if (pmd_sharing_possible) + mmu_notifier_invalidate_range_end(vma->vm_mm, + spmd_start, spmd_end); return ret; } |