Commit 297c5eee authored by Linus Torvalds's avatar Linus Torvalds
Browse files

mm: make the vma list be doubly linked 



It's a really simple list, and several of the users want to go backwards
in it to find the previous vma.  So rather than have to look up the
previous entry with 'find_vma_prev()' or something similar, just make it
doubly linked instead.

Tested-by: default avatarIan Campbell <ijc@hellion.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 36423a5e

include/linux/mm_types.h

+1 −1
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ struct vm_area_struct { 
					   within vm_mm. */



	/* linked list of VM areas per task, sorted by address */

	struct vm_area_struct *vm_next;

	struct vm_area_struct *vm_next, *vm_prev;



	pgprot_t vm_page_prot;		/* Access permissions of this VMA. */

	unsigned long vm_flags;		/* Flags, see mm.h. */

kernel/fork.c

+5 −2
Original line number Diff line number Diff line
@@ -300,7 +300,7 @@ out: 
#ifdef CONFIG_MMU

static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)

{

	struct vm_area_struct *mpnt, *tmp, **pprev;

	struct vm_area_struct *mpnt, *tmp, *prev, **pprev;

	struct rb_node **rb_link, *rb_parent;

	int retval;

	unsigned long charge;
@@ -328,6 +328,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 
	if (retval)

		goto out;



	prev = NULL;

	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {

		struct file *file;
@@ -359,7 +360,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 
			goto fail_nomem_anon_vma_fork;

		tmp->vm_flags &= ~VM_LOCKED;

		tmp->vm_mm = mm;

		tmp->vm_next = NULL;

		tmp->vm_next = tmp->vm_prev = NULL;

		file = tmp->vm_file;

		if (file) {

			struct inode *inode = file->f_path.dentry->d_inode;
@@ -392,6 +393,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 
		 */

		*pprev = tmp;

		pprev = &tmp->vm_next;

		tmp->vm_prev = prev;

		prev = tmp;



		__vma_link_rb(mm, tmp, rb_link, rb_parent);

		rb_link = &tmp->vm_rb.rb_right;

mm/mmap.c

+17 −4
Original line number Diff line number Diff line
@@ -388,17 +388,23 @@ static inline void 
__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,

		struct vm_area_struct *prev, struct rb_node *rb_parent)

{

	struct vm_area_struct *next;



	vma->vm_prev = prev;

	if (prev) {

		vma->vm_next = prev->vm_next;

		next = prev->vm_next;

		prev->vm_next = vma;

	} else {

		mm->mmap = vma;

		if (rb_parent)

			vma->vm_next = rb_entry(rb_parent,

			next = rb_entry(rb_parent,

					struct vm_area_struct, vm_rb);

		else

			vma->vm_next = NULL;

			next = NULL;

	}

	vma->vm_next = next;

	if (next)

		next->vm_prev = vma;

}



void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -483,7 +489,11 @@ static inline void 
__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,

		struct vm_area_struct *prev)

{

	prev->vm_next = vma->vm_next;

	struct vm_area_struct *next = vma->vm_next;



	prev->vm_next = next;

	if (next)

		next->vm_prev = prev;

	rb_erase(&vma->vm_rb, &mm->mm_rb);

	if (mm->mmap_cache == vma)

		mm->mmap_cache = prev;
@@ -1915,6 +1925,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 
	unsigned long addr;



	insertion_point = (prev ? &prev->vm_next : &mm->mmap);

	vma->vm_prev = NULL;

	do {

		rb_erase(&vma->vm_rb, &mm->mm_rb);

		mm->map_count--;
@@ -1922,6 +1933,8 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 
		vma = vma->vm_next;

	} while (vma && vma->vm_start < end);

	*insertion_point = vma;

	if (vma)

		vma->vm_prev = prev;

	tail_vma->vm_next = NULL;

	if (mm->unmap_area == arch_unmap_area)

		addr = prev ? prev->vm_end : mm->mmap_base;

mm/nommu.c

+5 −2
Original line number Diff line number Diff line
@@ -604,7 +604,7 @@ static void protect_vma(struct vm_area_struct *vma, unsigned long flags) 
 */

static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)

{

	struct vm_area_struct *pvma, **pp;

	struct vm_area_struct *pvma, **pp, *next;

	struct address_space *mapping;

	struct rb_node **p, *parent;
@@ -664,8 +664,11 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 
			break;

	}



	vma->vm_next = *pp;

	next = *pp;

	*pp = vma;

	vma->vm_next = next;

	if (next)

		next->vm_prev = vma;

}



/*

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