find_vma is called from kernel code where it is absolutely
sure that the mm_struct arg being passed to it is non-NULL.
Remove the if(mm) check.
This will also serve the purpose of mandating that the execution
context(user-mode/kernel-mode) be known before find_vma is called.
Also fixed 2 checkpatch.pl errors in the declaration
of the rb_node and vma_tmp local variables.
I have tested this patch on my x86 PC and there are no crashes
due to this in the course of normal desktop execution.
Signed-off-by: Kautuk Consul <consul.kautuk@xxxxxxxxx>
---
mm/mmap.c | 54 ++++++++++++++++++++++++++----------------------------
1 files changed, 26 insertions(+), 28 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index a7bf6a3..2b2fe67 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1587,35 +1587,33 @@ EXPORT_SYMBOL(get_unmapped_area);
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
- struct vm_area_struct *vma = NULL;
-
- if (mm) {
- /* Check the cache first. */
- /* (Cache hit rate is typically around 35%.) */
- vma = mm->mmap_cache;
- if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
- struct rb_node * rb_node;
-
- rb_node = mm->mm_rb.rb_node;
- vma = NULL;
-
- while (rb_node) {
- struct vm_area_struct * vma_tmp;
-
- vma_tmp = rb_entry(rb_node,
- struct vm_area_struct, vm_rb);
-
- if (vma_tmp->vm_end > addr) {
- vma = vma_tmp;
- if (vma_tmp->vm_start <= addr)
- break;
- rb_node = rb_node->rb_left;
- } else
- rb_node = rb_node->rb_right;
- }
- if (vma)
- mm->mmap_cache = vma;
+ struct vm_area_struct *vma;
+
+ /* Check the cache first. */
+ /* (Cache hit rate is typically around 35%.) */
+ vma = mm->mmap_cache;
+ if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
+ struct rb_node *rb_node;
+
+ rb_node = mm->mm_rb.rb_node;
+ vma = NULL;
+
+ while (rb_node) {
+ struct vm_area_struct *vma_tmp;
+
+ vma_tmp = rb_entry(rb_node,
+ struct vm_area_struct, vm_rb);
+
+ if (vma_tmp->vm_end > addr) {
+ vma = vma_tmp;
+ if (vma_tmp->vm_start <= addr)
+ break;
+ rb_node = rb_node->rb_left;
+ } else
+ rb_node = rb_node->rb_right;
}
+ if (vma)
+ mm->mmap_cache = vma;
}
return vma;
}
--
1.7.5.4
--
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