From: Chris Wright <chrisw@osdl.org>
Successive mlock/munlock calls can leave fragmented vmas because they can
be split but not merged. Give mlock et. al. full vma merging support.
While we're at it, move *pprev assignment above first split_vma in
mprotect_fixup to keep it in step with mlock_fixup (which for mlockall
ignores errors yet still needs a valid prev pointer).
Signed-off-by: Chris Wright <chrisw@osdl.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/mm/mlock.c | 49 ++++++++++++++++++++++++++++++++++---------------
25-akpm/mm/mprotect.c | 7 ++-----
2 files changed, 36 insertions(+), 20 deletions(-)
diff -puN mm/mlock.c~allow-vma-merging-with-mlock-et-al mm/mlock.c
--- 25/mm/mlock.c~allow-vma-merging-with-mlock-et-al 2005-02-28 16:44:35.000000000 -0800
+++ 25-akpm/mm/mlock.c 2005-02-28 16:44:35.000000000 -0800
@@ -7,18 +7,32 @@
#include <linux/mman.h>
#include <linux/mm.h>
+#include <linux/mempolicy.h>
#include <linux/syscalls.h>
-static int mlock_fixup(struct vm_area_struct * vma,
+static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
unsigned long start, unsigned long end, unsigned int newflags)
{
struct mm_struct * mm = vma->vm_mm;
+ pgoff_t pgoff;
int pages;
int ret = 0;
- if (newflags == vma->vm_flags)
+ if (newflags == vma->vm_flags) {
+ *prev = vma;
goto out;
+ }
+
+ pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
+ *prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
+ vma->vm_file, pgoff, vma_policy(vma));
+ if (*prev) {
+ vma = *prev;
+ goto success;
+ }
+
+ *prev = vma;
if (start != vma->vm_start) {
ret = split_vma(mm, vma, start, 1);
@@ -32,6 +46,7 @@ static int mlock_fixup(struct vm_area_st
goto out;
}
+success:
/*
* vm_flags is protected by the mmap_sem held in write mode.
* It's okay if try_to_unmap_one unmaps a page just after we
@@ -59,7 +74,7 @@ out:
static int do_mlock(unsigned long start, size_t len, int on)
{
unsigned long nstart, end, tmp;
- struct vm_area_struct * vma, * next;
+ struct vm_area_struct * vma, * prev;
int error;
len = PAGE_ALIGN(len);
@@ -68,10 +83,13 @@ static int do_mlock(unsigned long start,
return -EINVAL;
if (end == start)
return 0;
- vma = find_vma(current->mm, start);
+ vma = find_vma_prev(current->mm, start, &prev);
if (!vma || vma->vm_start > start)
return -ENOMEM;
+ if (start > vma->vm_start)
+ prev = vma;
+
for (nstart = start ; ; ) {
unsigned int newflags;
@@ -81,18 +99,19 @@ static int do_mlock(unsigned long start,
if (!on)
newflags &= ~VM_LOCKED;
- if (vma->vm_end >= end) {
- error = mlock_fixup(vma, nstart, end, newflags);
- break;
- }
-
tmp = vma->vm_end;
- next = vma->vm_next;
- error = mlock_fixup(vma, nstart, tmp, newflags);
+ if (tmp > end)
+ tmp = end;
+ error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
if (error)
break;
nstart = tmp;
- vma = next;
+ if (nstart < prev->vm_end)
+ nstart = prev->vm_end;
+ if (nstart >= end)
+ break;
+
+ vma = prev->vm_next;
if (!vma || vma->vm_start != nstart) {
error = -ENOMEM;
break;
@@ -141,7 +160,7 @@ asmlinkage long sys_munlock(unsigned lon
static int do_mlockall(int flags)
{
- struct vm_area_struct * vma;
+ struct vm_area_struct * vma, * prev = NULL;
unsigned int def_flags = 0;
if (flags & MCL_FUTURE)
@@ -150,7 +169,7 @@ static int do_mlockall(int flags)
if (flags == MCL_FUTURE)
goto out;
- for (vma = current->mm->mmap; vma ; vma = vma->vm_next) {
+ for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
unsigned int newflags;
newflags = vma->vm_flags | VM_LOCKED;
@@ -158,7 +177,7 @@ static int do_mlockall(int flags)
newflags &= ~VM_LOCKED;
/* Ignore errors */
- mlock_fixup(vma, vma->vm_start, vma->vm_end, newflags);
+ mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
}
out:
return 0;
diff -puN mm/mprotect.c~allow-vma-merging-with-mlock-et-al mm/mprotect.c
--- 25/mm/mprotect.c~allow-vma-merging-with-mlock-et-al 2005-02-28 16:44:35.000000000 -0800
+++ 25-akpm/mm/mprotect.c 2005-02-28 16:44:35.000000000 -0800
@@ -185,16 +185,13 @@ mprotect_fixup(struct vm_area_struct *vm
goto success;
}
+ *pprev = vma;
+
if (start != vma->vm_start) {
error = split_vma(mm, vma, start, 1);
if (error)
goto fail;
}
- /*
- * Unless it returns an error, this function always sets *pprev to
- * the first vma for which vma->vm_end >= end.
- */
- *pprev = vma;
if (end != vma->vm_end) {
error = split_vma(mm, vma, end, 0);
_