__zap_vma_range() has two callers, whereby zap_page_range_single_batched() documents that the range must fit into the VMA range.
So move adjusting the range to unmap_vmas() where it is actually required and add a safety check in __zap_vma_range() instead. In unmap_vmas(), we'd never expect to have empty ranges (otherwise, why have the vma in there in the first place). __zap_vma_range() will no longer be called with start == end, so cleanup the function a bit. While at it, simplify the overly long comment to its core message. We will no longer call uprobe_munmap() for start == end, which actually seems to be the right thing to do. Note that hugetlb_zap_begin()->...->adjust_range_if_pmd_sharing_possible() cannot result in the range exceeding the vma range. Signed-off-by: David Hildenbrand (Arm) <[email protected]> --- mm/memory.c | 58 +++++++++++++++++++++-------------------------------- 1 file changed, 23 insertions(+), 35 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index f0aaec57a66b..fdcd2abf29c2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2073,44 +2073,28 @@ static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, tlb_end_vma(tlb, vma); } - -static void __zap_vma_range(struct mmu_gather *tlb, - struct vm_area_struct *vma, unsigned long start_addr, - unsigned long end_addr, struct zap_details *details) +static void __zap_vma_range(struct mmu_gather *tlb, struct vm_area_struct *vma, + unsigned long start, unsigned long end, + struct zap_details *details) { - unsigned long start = max(vma->vm_start, start_addr); - unsigned long end; - - if (start >= vma->vm_end) - return; - end = min(vma->vm_end, end_addr); - if (end <= vma->vm_start) - return; + VM_WARN_ON_ONCE(start >= end || !range_in_vma(vma, start, end)); if (vma->vm_file) uprobe_munmap(vma, start, end); - if (start != end) { - if (unlikely(is_vm_hugetlb_page(vma))) { - /* - * It is undesirable to test vma->vm_file as it - * should be non-null for valid hugetlb area. - * However, vm_file will be NULL in the error - * cleanup path of mmap_region. When - * hugetlbfs ->mmap method fails, - * mmap_region() nullifies vma->vm_file - * before calling this function to clean up. - * Since no pte has actually been setup, it is - * safe to do nothing in this case. - */ - if (vma->vm_file) { - zap_flags_t zap_flags = details ? - details->zap_flags : 0; - __unmap_hugepage_range(tlb, vma, start, end, - NULL, zap_flags); - } - } else - unmap_page_range(tlb, vma, start, end, details); + if (unlikely(is_vm_hugetlb_page(vma))) { + zap_flags_t zap_flags = details ? details->zap_flags : 0; + + /* + * vm_file will be NULL when we fail early while instantiating + * a new mapping. In this case, no pages were mapped yet and + * there is nothing to do. + */ + if (!vma->vm_file) + return; + __unmap_hugepage_range(tlb, vma, start, end, NULL, zap_flags); + } else { + unmap_page_range(tlb, vma, start, end, details); } } @@ -2174,8 +2158,9 @@ void unmap_vmas(struct mmu_gather *tlb, struct unmap_desc *unmap) unmap->vma_start, unmap->vma_end); mmu_notifier_invalidate_range_start(&range); do { - unsigned long start = unmap->vma_start; - unsigned long end = unmap->vma_end; + unsigned long start = max(vma->vm_start, unmap->vma_start); + unsigned long end = min(vma->vm_end, unmap->vma_end); + hugetlb_zap_begin(vma, &start, &end); __zap_vma_range(tlb, vma, start, end, &details); hugetlb_zap_end(vma, &details); @@ -2204,6 +2189,9 @@ void zap_page_range_single_batched(struct mmu_gather *tlb, VM_WARN_ON_ONCE(!tlb || tlb->mm != vma->vm_mm); + if (unlikely(!size)) + return; + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, address, end); hugetlb_zap_begin(vma, &range.start, &range.end); -- 2.43.0
