diff options
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 43 |
1 files changed, 27 insertions, 16 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 8de5a6b5a172..45e305d182f6 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4612,7 +4612,14 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma) kref_get(&resv->refs); } - hugetlb_vma_lock_alloc(vma); + /* + * vma_lock structure for sharable mappings is vma specific. + * Clear old pointer (if copied via vm_area_dup) and create new. + */ + if (vma->vm_flags & VM_MAYSHARE) { + vma->vm_private_data = NULL; + hugetlb_vma_lock_alloc(vma); + } } static void hugetlb_vm_op_close(struct vm_area_struct *vma) @@ -5168,19 +5175,23 @@ void __unmap_hugepage_range_final(struct mmu_gather *tlb, unsigned long end, struct page *ref_page, zap_flags_t zap_flags) { + hugetlb_vma_lock_write(vma); + i_mmap_lock_write(vma->vm_file->f_mapping); + __unmap_hugepage_range(tlb, vma, start, end, ref_page, zap_flags); /* - * Clear this flag so that x86's huge_pmd_share page_table_shareable - * test will fail on a vma being torn down, and not grab a page table - * on its way out. We're lucky that the flag has such an appropriate - * name, and can in fact be safely cleared here. We could clear it - * before the __unmap_hugepage_range above, but all that's necessary - * is to clear it before releasing the i_mmap_rwsem. This works - * because in the context this is called, the VMA is about to be - * destroyed and the i_mmap_rwsem is held. + * Unlock and free the vma lock before releasing i_mmap_rwsem. When + * the vma_lock is freed, this makes the vma ineligible for pmd + * sharing. And, i_mmap_rwsem is required to set up pmd sharing. + * This is important as page tables for this unmapped range will + * be asynchrously deleted. If the page tables are shared, there + * will be issues when accessed by someone else. */ - vma->vm_flags &= ~VM_MAYSHARE; + hugetlb_vma_unlock_write(vma); + hugetlb_vma_lock_free(vma); + + i_mmap_unlock_write(vma->vm_file->f_mapping); } void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, @@ -6664,10 +6675,13 @@ static unsigned long page_table_shareable(struct vm_area_struct *svma, /* * match the virtual addresses, permission and the alignment of the * page table page. + * + * Also, vma_lock (vm_private_data) is required for sharing. */ if (pmd_index(addr) != pmd_index(saddr) || vm_flags != svm_flags || - !range_in_vma(svma, sbase, s_end)) + !range_in_vma(svma, sbase, s_end) || + !svma->vm_private_data) return 0; return saddr; @@ -6817,12 +6831,9 @@ void hugetlb_vma_lock_release(struct kref *kref) static void hugetlb_vma_lock_free(struct vm_area_struct *vma) { /* - * Only present in sharable vmas. See comment in - * __unmap_hugepage_range_final about how VM_SHARED could - * be set without VM_MAYSHARE. As a result, we need to - * check if either is set in the free path. + * Only present in sharable vmas. */ - if (!vma || !(vma->vm_flags & (VM_MAYSHARE | VM_SHARED))) + if (!vma || !__vma_shareable_flags_pmd(vma)) return; if (vma->vm_private_data) { |