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authorLinus Torvalds <torvalds@linux-foundation.org>2010-08-20 16:24:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-21 08:49:21 -0700
commit297c5eee372478fc32fec5fe8eed711eedb13f3d (patch)
tree18415eae0833ff4767943f985900524d6b1d73f1
parent36423a5ed5e4ea95ceedb68fad52965033e11639 (diff)
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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: Ian Campbell <ijc@hellion.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/mm_types.h2
-rw-r--r--kernel/fork.c7
-rw-r--r--mm/mmap.c21
-rw-r--r--mm/nommu.c7
4 files changed, 28 insertions, 9 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b8bb9a6a1f37..ee7e258627f9 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -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. */
diff --git a/kernel/fork.c b/kernel/fork.c
index 856eac3ec52e..b7e9d60a675d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -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;
diff --git a/mm/mmap.c b/mm/mmap.c
index 31003338b978..331e51af38c9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -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;
diff --git a/mm/nommu.c b/mm/nommu.c
index efa9a380335e..88ff091eb07a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -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;
}
/*