lkml.org 
[lkml]   [2011]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/6] nommu: sort mm->mmap list properly
Date
@vma added into @mm should be sorted by start addr, end addr and VMA struct
addr in that order because we may get identical VMAs in the @mm. However
this was true only for the rbtree, not for the list.

This patch fixes this by remembering 'rb_prev' during the tree traversal
like find_vma_prepare() does and linking the @vma via __vma_link_list().
After this patch, we can iterate the whole VMAs in correct order simply
by using @mm->mmap list.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
mm/nommu.c | 62 ++++++++++++++++++++++++++++++++++++++---------------------
1 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index e7dbd3fae187..20d9c330eb0e 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -672,6 +672,30 @@ static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
#endif
}

+/* borrowed from mm/mmap.c */
+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) {
+ next = prev->vm_next;
+ prev->vm_next = vma;
+ } else {
+ mm->mmap = vma;
+ if (rb_parent)
+ next = rb_entry(rb_parent,
+ struct vm_area_struct, vm_rb);
+ else
+ next = NULL;
+ }
+ vma->vm_next = next;
+ if (next)
+ next->vm_prev = vma;
+}
+
/*
* add a VMA into a process's mm_struct in the appropriate place in the list
* and tree and add to the address space's page tree also if not an anonymous
@@ -680,9 +704,9 @@ 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, *next;
+ struct vm_area_struct *pvma, *prev;
struct address_space *mapping;
- struct rb_node **p, *parent;
+ struct rb_node **p, *parent, *rb_prev;

kenter(",%p", vma);

@@ -703,7 +727,7 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
}

/* add the VMA to the tree */
- parent = NULL;
+ parent = rb_prev = NULL;
p = &mm->mm_rb.rb_node;
while (*p) {
parent = *p;
@@ -713,17 +737,20 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
* (the latter is necessary as we may get identical VMAs) */
if (vma->vm_start < pvma->vm_start)
p = &(*p)->rb_left;
- else if (vma->vm_start > pvma->vm_start)
+ else if (vma->vm_start > pvma->vm_start) {
+ rb_prev = parent;
p = &(*p)->rb_right;
- else if (vma->vm_end < pvma->vm_end)
+ } else if (vma->vm_end < pvma->vm_end)
p = &(*p)->rb_left;
- else if (vma->vm_end > pvma->vm_end)
+ else if (vma->vm_end > pvma->vm_end) {
+ rb_prev = parent;
p = &(*p)->rb_right;
- else if (vma < pvma)
+ } else if (vma < pvma)
p = &(*p)->rb_left;
- else if (vma > pvma)
+ else if (vma > pvma) {
+ rb_prev = parent;
p = &(*p)->rb_right;
- else
+ } else
BUG();
}

@@ -731,20 +758,11 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
rb_insert_color(&vma->vm_rb, &mm->mm_rb);

/* add VMA to the VMA list also */
- for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
- if (pvma->vm_start > vma->vm_start)
- break;
- if (pvma->vm_start < vma->vm_start)
- continue;
- if (pvma->vm_end < vma->vm_end)
- break;
- }
+ prev = NULL;
+ if (rb_prev)
+ prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);

- next = *pp;
- *pp = vma;
- vma->vm_next = next;
- if (next)
- next->vm_prev = vma;
+ __vma_link_list(mm, vma, prev, parent);
}

/*
--
1.7.4


\
 
 \ /
  Last update: 2011-03-28 15:59    [W:0.069 / U:6.104 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site