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mm/mmap: introduce dup_vma_anon() helper
Create a helper for duplicating the anon vma when adjusting the vma. This simplifies the logic of __vma_adjust(). Link: https://lkml.kernel.org/r/20230120162650.984577-47-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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parent
cf51e86dfb
commit
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1 changed files with 40 additions and 34 deletions
74
mm/mmap.c
74
mm/mmap.c
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@ -617,6 +617,29 @@ static inline void vma_complete(struct vma_prepare *vp,
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uprobe_mmap(vp->insert);
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uprobe_mmap(vp->insert);
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}
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}
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/*
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* dup_anon_vma() - Helper function to duplicate anon_vma
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* @dst: The destination VMA
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* @src: The source VMA
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*
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* Returns: 0 on success.
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*/
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static inline int dup_anon_vma(struct vm_area_struct *dst,
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struct vm_area_struct *src)
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{
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/*
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* Easily overlooked: when mprotect shifts the boundary, make sure the
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* expanding vma has anon_vma set if the shrinking vma had, to cover any
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* anon pages imported.
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*/
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if (src->anon_vma && !dst->anon_vma) {
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dst->anon_vma = src->anon_vma;
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return anon_vma_clone(dst, src);
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}
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return 0;
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}
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/*
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/*
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* vma_expand - Expand an existing VMA
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* vma_expand - Expand an existing VMA
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*
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*
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@ -642,15 +665,12 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
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struct vma_prepare vp;
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struct vma_prepare vp;
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if (next && (vma != next) && (end == next->vm_end)) {
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if (next && (vma != next) && (end == next->vm_end)) {
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remove_next = true;
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int ret;
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if (next->anon_vma && !vma->anon_vma) {
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int error;
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vma->anon_vma = next->anon_vma;
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remove_next = true;
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error = anon_vma_clone(vma, next);
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ret = dup_anon_vma(vma, next);
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if (error)
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if (ret)
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return error;
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return ret;
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}
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}
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}
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init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
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init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
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@ -739,10 +759,11 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
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struct file *file = vma->vm_file;
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struct file *file = vma->vm_file;
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bool vma_changed = false;
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bool vma_changed = false;
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long adjust_next = 0;
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long adjust_next = 0;
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struct vm_area_struct *exporter = NULL, *importer = NULL;
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struct vma_prepare vma_prep;
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struct vma_prepare vma_prep;
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if (next) {
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if (next) {
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int error = 0;
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if (end >= next->vm_end) {
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if (end >= next->vm_end) {
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/*
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/*
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* vma expands, overlapping all the next, and
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* vma expands, overlapping all the next, and
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@ -777,15 +798,14 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
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end != remove2->vm_end);
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end != remove2->vm_end);
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}
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}
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exporter = next;
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importer = vma;
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/*
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/*
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* If next doesn't have anon_vma, import from vma after
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* If next doesn't have anon_vma, import from vma after
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* next, if the vma overlaps with it.
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* next, if the vma overlaps with it.
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*/
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*/
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if (remove2 != NULL && !next->anon_vma)
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if (remove != NULL && !next->anon_vma)
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exporter = remove2;
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error = dup_anon_vma(vma, remove2);
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else
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error = dup_anon_vma(vma, remove);
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} else if (end > next->vm_start) {
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} else if (end > next->vm_start) {
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/*
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/*
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@ -793,9 +813,8 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
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* mprotect case 5 shifting the boundary up.
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* mprotect case 5 shifting the boundary up.
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*/
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*/
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adjust_next = (end - next->vm_start);
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adjust_next = (end - next->vm_start);
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exporter = next;
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VM_WARN_ON(expand != vma);
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importer = vma;
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error = dup_anon_vma(vma, next);
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VM_WARN_ON(expand != importer);
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} else if (end < vma->vm_end) {
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} else if (end < vma->vm_end) {
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/*
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/*
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* vma shrinks, and !insert tells it's not
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* vma shrinks, and !insert tells it's not
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@ -803,24 +822,11 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
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* mprotect case 4 shifting the boundary down.
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* mprotect case 4 shifting the boundary down.
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*/
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*/
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adjust_next = -(vma->vm_end - end);
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adjust_next = -(vma->vm_end - end);
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exporter = vma;
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VM_WARN_ON(expand != next);
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importer = next;
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error = dup_anon_vma(next, vma);
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VM_WARN_ON(expand != importer);
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}
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/*
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* Easily overlooked: when mprotect shifts the boundary,
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* make sure the expanding vma has anon_vma set if the
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* shrinking vma had, to cover any anon pages imported.
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*/
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if (exporter && exporter->anon_vma && !importer->anon_vma) {
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int error;
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importer->anon_vma = exporter->anon_vma;
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error = anon_vma_clone(importer, exporter);
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if (error)
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return error;
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}
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}
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if (error)
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return error;
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}
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}
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if (vma_iter_prealloc(vmi))
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if (vma_iter_prealloc(vmi))
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