[PATCH] madvise: merge the maps
This attempts to merge back the split maps. This code is mostly copied
from Chrisw's mlock merging from post 2.6.11 trees. The only difference is
in munmapped_error handling. Also passed prev to willneed/dontneed,
eventhogh they do not handle it now, since I felt it will be cleaner,
instead of handling prev in madvise_vma in some cases and in subfunction in
some cases.
Signed-off-by: Prasanna Meda <pmeda@akamai.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/madvise.c b/mm/madvise.c
index 75b81ad..e310805 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -8,17 +8,20 @@
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/syscalls.h>
+#include <linux/mempolicy.h>
#include <linux/hugetlb.h>
/*
* We can potentially split a vm area into separate
* areas, each area with its own behavior.
*/
-static long madvise_behavior(struct vm_area_struct * vma, unsigned long start,
- unsigned long end, int behavior)
+static long madvise_behavior(struct vm_area_struct * vma,
+ struct vm_area_struct **prev,
+ unsigned long start, unsigned long end, int behavior)
{
struct mm_struct * mm = vma->vm_mm;
int error = 0;
+ pgoff_t pgoff;
int new_flags = vma->vm_flags & ~VM_READHINTMASK;
switch (behavior) {
@@ -32,8 +35,20 @@
break;
}
- if (new_flags == vma->vm_flags)
- goto out;
+ if (new_flags == vma->vm_flags) {
+ *prev = vma;
+ goto success;
+ }
+
+ pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+ *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
+ vma->vm_file, pgoff, vma_policy(vma));
+ if (*prev) {
+ vma = *prev;
+ goto success;
+ }
+
+ *prev = vma;
if (start != vma->vm_start) {
error = split_vma(mm, vma, start, 1);
@@ -56,6 +71,7 @@
out:
if (error == -ENOMEM)
error = -EAGAIN;
+success:
return error;
}
@@ -63,6 +79,7 @@
* Schedule all required I/O operations. Do not wait for completion.
*/
static long madvise_willneed(struct vm_area_struct * vma,
+ struct vm_area_struct ** prev,
unsigned long start, unsigned long end)
{
struct file *file = vma->vm_file;
@@ -70,6 +87,7 @@
if (!file)
return -EBADF;
+ *prev = vma;
start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
if (end > vma->vm_end)
end = vma->vm_end;
@@ -100,8 +118,10 @@
* dirty pages is already available as msync(MS_INVALIDATE).
*/
static long madvise_dontneed(struct vm_area_struct * vma,
+ struct vm_area_struct ** prev,
unsigned long start, unsigned long end)
{
+ *prev = vma;
if ((vma->vm_flags & VM_LOCKED) || is_vm_hugetlb_page(vma))
return -EINVAL;
@@ -116,8 +136,8 @@
return 0;
}
-static long madvise_vma(struct vm_area_struct * vma, unsigned long start,
- unsigned long end, int behavior)
+static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
+ unsigned long start, unsigned long end, int behavior)
{
long error = -EBADF;
@@ -125,15 +145,15 @@
case MADV_NORMAL:
case MADV_SEQUENTIAL:
case MADV_RANDOM:
- error = madvise_behavior(vma, start, end, behavior);
+ error = madvise_behavior(vma, prev, start, end, behavior);
break;
case MADV_WILLNEED:
- error = madvise_willneed(vma, start, end);
+ error = madvise_willneed(vma, prev, start, end);
break;
case MADV_DONTNEED:
- error = madvise_dontneed(vma, start, end);
+ error = madvise_dontneed(vma, prev, start, end);
break;
default:
@@ -180,8 +200,8 @@
*/
asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior)
{
- unsigned long end;
- struct vm_area_struct * vma;
+ unsigned long end, tmp;
+ struct vm_area_struct * vma, *prev;
int unmapped_error = 0;
int error = -EINVAL;
size_t len;
@@ -207,40 +227,42 @@
/*
* If the interval [start,end) covers some unmapped address
* ranges, just ignore them, but return -ENOMEM at the end.
+ * - different from the way of handling in mlock etc.
*/
- vma = find_vma(current->mm, start);
+ vma = find_vma_prev(current->mm, start, &prev);
+ if (!vma && prev)
+ vma = prev->vm_next;
for (;;) {
/* Still start < end. */
error = -ENOMEM;
if (!vma)
goto out;
- /* Here start < vma->vm_end. */
+ /* Here start < (end|vma->vm_end). */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
+ if (start >= end)
+ goto out;
}
- /* Here vma->vm_start <= start < vma->vm_end. */
- if (end <= vma->vm_end) {
- if (start < end) {
- error = madvise_vma(vma, start, end,
- behavior);
- if (error)
- goto out;
- }
- error = unmapped_error;
- goto out;
- }
+ /* Here vma->vm_start <= start < (end|vma->vm_end) */
+ tmp = vma->vm_end;
+ if (end < tmp)
+ tmp = end;
- /* Here vma->vm_start <= start < vma->vm_end < end. */
- error = madvise_vma(vma, start, vma->vm_end, behavior);
+ /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
+ error = madvise_vma(vma, &prev, start, tmp, behavior);
if (error)
goto out;
- start = vma->vm_end;
- vma = vma->vm_next;
+ start = tmp;
+ if (start < prev->vm_end)
+ start = prev->vm_end;
+ error = unmapped_error;
+ if (start >= end)
+ goto out;
+ vma = prev->vm_next;
}
-
out:
up_write(¤t->mm->mmap_sem);
return error;