diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 6893eb8c66e5..62dce9578242 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -742,12 +742,13 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, /* * If the vma has a ->close operation then the driver probably needs to release - * per-vma resources, so we don't attempt to merge those. + * per-vma resources, so we don't attempt to merge those if the caller indicates + * the current vma may be removed as part of the merge. */ static inline bool is_mergeable_vma(struct vm_area_struct *vma, struct file *file, unsigned long vm_flags, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, - struct anon_vma_name *anon_name) + struct anon_vma_name *anon_name, bool may_remove_vma) { /* * VM_SOFTDIRTY should not prevent from VMA merging, if we @@ -761,7 +762,7 @@ static inline bool is_mergeable_vma(struct vm_area_struct *vma, return false; if (vma->vm_file != file) return false; - if (vma->vm_ops && vma->vm_ops->close) + if (may_remove_vma && vma->vm_ops && vma->vm_ops->close) return false; if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) return false; @@ -793,6 +794,8 @@ static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1, * We don't check here for the merged mmap wrapping around the end of pagecache * indices (16TB on ia32) because do_mmap() does not permit mmap's which * wrap, nor mmaps which cover the final page at index -1UL. + * + * We assume the vma may be removed as part of the merge. */ static bool can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, @@ -800,7 +803,7 @@ can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, struct anon_vma_name *anon_name) { - if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) && + if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) && is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { if (vma->vm_pgoff == vm_pgoff) return true; @@ -814,6 +817,8 @@ can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, * * We cannot merge two vmas if they have differently assigned (non-NULL) * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. + * + * We assume that vma is not removed as part of the merge. */ static bool can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, @@ -821,7 +826,7 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx, struct anon_vma_name *anon_name) { - if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) && + if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) && is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { pgoff_t vm_pglen; vm_pglen = vma_pages(vma); |