Commit 68cefec5 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

mm/mmap: introduce init_vma_prep() and init_multi_vma_prep() 

Add init_vma_prep() and init_multi_vma_prep() to set up the struct
vma_prepare.  This is to abstract the locking when adjusting the VMAs.

Also change __vma_adjust() variable remove_next int in favour of a pointer
to the VMA to remove.  Rename next_next to remove2 since this better
reflects its use.

Link: https://lkml.kernel.org/r/20230120162650.984577-43-Liam.Howlett@oracle.com


Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 9303d3e1

mm/mmap.c

+61 −47
Original line number Diff line number Diff line
@@ -457,6 +457,45 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) 
	return 0;

}



/*

 * init_multi_vma_prep() - Initializer for struct vma_prepare

 * @vp: The vma_prepare struct

 * @vma: The vma that will be altered once locked

 * @next: The next vma if it is to be adjusted

 * @remove: The first vma to be removed

 * @remove2: The second vma to be removed

 */

static inline void init_multi_vma_prep(struct vma_prepare *vp,

		struct vm_area_struct *vma, struct vm_area_struct *next,

		struct vm_area_struct *remove, struct vm_area_struct *remove2)

{

	memset(vp, 0, sizeof(struct vma_prepare));

	vp->vma = vma;

	vp->anon_vma = vma->anon_vma;

	vp->remove = remove;

	vp->remove2 = remove2;

	vp->adj_next = next;

	if (!vp->anon_vma && next)

		vp->anon_vma = next->anon_vma;



	vp->file = vma->vm_file;

	if (vp->file)

		vp->mapping = vma->vm_file->f_mapping;



}



/*

 * init_vma_prep() - Initializer wrapper for vma_prepare struct

 * @vp: The vma_prepare struct

 * @vma: The vma that will be altered once locked

 */

static inline void init_vma_prep(struct vma_prepare *vp,

				 struct vm_area_struct *vma)

{

	init_multi_vma_prep(vp, vma, NULL, NULL, NULL);

}





/*

 * vma_prepare() - Helper function for handling locking VMAs prior to altering

 * @vp: The initialized vma_prepare struct
@@ -566,7 +605,7 @@ static inline void vma_complete(struct vma_prepare *vp, 


		/*

		 * In mprotect's case 6 (see comments on vma_merge),

		 * we must remove next_next too.

		 * we must remove the one after next as well.

		 */

		if (vp->remove2) {

			vp->remove = vp->remove2;
@@ -599,17 +638,14 @@ inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 
		      unsigned long start, unsigned long end, pgoff_t pgoff,

		      struct vm_area_struct *next)

{

	bool remove_next = false;

	struct vma_prepare vp;



	memset(&vp, 0, sizeof(vp));

	vp.vma = vma;

	vp.anon_vma = vma->anon_vma;

	if (next && (vma != next) && (end == next->vm_end)) {

		vp.remove = next;

		remove_next = true;

		if (next->anon_vma && !vma->anon_vma) {

			int error;



			vp.anon_vma = next->anon_vma;

			vma->anon_vma = next->anon_vma;

			error = anon_vma_clone(vma, next);

			if (error)
@@ -617,6 +653,7 @@ inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 
		}

	}



	init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);

	/* Not merging but overwriting any part of next is not handled. */

	VM_WARN_ON(next && !vp.remove &&

		  next != vma && end > next->vm_start);
@@ -627,11 +664,6 @@ inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 
		goto nomem;



	vma_adjust_trans_huge(vma, start, end, 0);



	vp.file = vma->vm_file;

	if (vp.file)

		vp.mapping = vp.file->f_mapping;



	/* VMA iterator points to previous, so set to start if necessary */

	if (vma_iter_addr(vmi) != start)

		vma_iter_set(vmi, start);
@@ -662,14 +694,13 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, 
	struct vm_area_struct *insert, struct vm_area_struct *expand)

{

	struct mm_struct *mm = vma->vm_mm;

	struct vm_area_struct *next_next = NULL;	/* uninit var warning */

	struct vm_area_struct *remove2 = NULL;

	struct vm_area_struct *remove = NULL;

	struct vm_area_struct *next = find_vma(mm, vma->vm_end);

	struct vm_area_struct *orig_vma = vma;

	struct anon_vma *anon_vma = NULL;

	struct file *file = vma->vm_file;

	bool vma_changed = false;

	long adjust_next = 0;

	int remove_next = 0;

	struct vm_area_struct *exporter = NULL, *importer = NULL;

	struct vma_prepare vma_prep;
@@ -688,25 +719,24 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, 
				 */

				VM_WARN_ON(end != next->vm_end);

				/*

				 * remove_next == 3 means we're

				 * removing "vma" and that to do so we

				 * we're removing "vma" and that to do so we

				 * swapped "vma" and "next".

				 */

				remove_next = 3;

				VM_WARN_ON(file != next->vm_file);

				swap(vma, next);

				remove = next;

			} else {

				VM_WARN_ON(expand != vma);

				/*

				 * case 1, 6, 7, remove_next == 2 is case 6,

				 * remove_next == 1 is case 1 or 7.

				 * case 1, 6, 7, remove next.

				 * case 6 also removes the one beyond next

				 */

				remove_next = 1 + (end > next->vm_end);

				if (remove_next == 2)

					next_next = find_vma(mm, next->vm_end);

				remove = next;

				if (end > next->vm_end)

					remove2 = find_vma(mm, next->vm_end);



				VM_WARN_ON(remove_next == 2 &&

					   end != next_next->vm_end);

				VM_WARN_ON(remove2 != NULL &&

					   end != remove2->vm_end);

			}



			exporter = next;
@@ -716,8 +746,8 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, 
			 * If next doesn't have anon_vma, import from vma after

			 * next, if the vma overlaps with it.

			 */

			if (remove_next == 2 && !next->anon_vma)

				exporter = next_next;

			if (remove2 != NULL && !next->anon_vma)

				exporter = remove2;



		} else if (end > next->vm_start) {

			/*
@@ -758,30 +788,14 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, 
	if (vma_iter_prealloc(vmi))

		return -ENOMEM;



	anon_vma = vma->anon_vma;

	if (!anon_vma && adjust_next)

		anon_vma = next->anon_vma;



	if (anon_vma)

		VM_WARN_ON(adjust_next && next->anon_vma &&

			   anon_vma != next->anon_vma);



	vma_adjust_trans_huge(orig_vma, start, end, adjust_next);



	memset(&vma_prep, 0, sizeof(vma_prep));

	vma_prep.vma = vma;

	vma_prep.anon_vma = anon_vma;

	vma_prep.file = file;

	if (adjust_next)

		vma_prep.adj_next = next;

	if (file)

		vma_prep.mapping = file->f_mapping;

	vma_prep.insert = insert;

	if (remove_next) {

		vma_prep.remove = next;

		vma_prep.remove2 = next_next;

	}

	init_multi_vma_prep(&vma_prep, vma, adjust_next ? next : NULL, remove,

			    remove2);

	VM_WARN_ON(vma_prep.anon_vma && adjust_next && next->anon_vma &&

		   vma_prep.anon_vma != next->anon_vma);



	vma_prep.insert = insert;

	vma_prepare(&vma_prep);



	if (start != vma->vm_start) {