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Subject[RFC][PATCH 08/26] mm, mpol: Simplify do_mbind()
Code flow got a little convoluted, try and straighten it some.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
mm/mempolicy.c | 73 +++++++++++++++++++++++++++++----------------------------
1 file changed, 38 insertions(+), 35 deletions(-)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1054,9 +1054,9 @@ static long do_mbind(unsigned long start
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
- struct mempolicy *new;
+ struct mempolicy *new = NULL;
unsigned long end;
- int err;
+ int err, nr_failed = 0;
LIST_HEAD(pagelist);

if (flags & ~(unsigned long)MPOL_MF_VALID)
@@ -1078,13 +1078,15 @@ static long do_mbind(unsigned long start
if (end == start)
return 0;

- new = mpol_new(mode, mode_flags, nmask);
- if (IS_ERR(new))
- return PTR_ERR(new);
+ if (mode != MPOL_NOOP) {
+ new = mpol_new(mode, mode_flags, nmask);
+ if (IS_ERR(new))
+ return PTR_ERR(new);

- if (flags & MPOL_MF_LAZY)
- new->flags |= MPOL_F_MOF;
+ if (flags & MPOL_MF_LAZY)
+ new->flags |= MPOL_F_MOF;

+ }
/*
* If we are using the default policy then operation
* on discontinuous address spaces is okay after all
@@ -1097,56 +1099,57 @@ static long do_mbind(unsigned long start
nmask ? nodes_addr(*nmask)[0] : -1);

if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
-
err = migrate_prep();
if (err)
goto mpol_out;
}
- {
+
+ down_write(&mm->mmap_sem);
+
+ if (mode != MPOL_NOOP) {
NODEMASK_SCRATCH(scratch);
+ err = -ENOMEM;
if (scratch) {
- down_write(&mm->mmap_sem);
task_lock(current);
err = mpol_set_nodemask(new, nmask, scratch);
task_unlock(current);
- if (err)
- up_write(&mm->mmap_sem);
- } else
- err = -ENOMEM;
+ }
NODEMASK_SCRATCH_FREE(scratch);
+ if (err)
+ goto mpol_out_unlock;
}
- if (err)
- goto mpol_out;

vma = check_range(mm, start, end, nmask,
flags | MPOL_MF_INVERT, &pagelist);

err = PTR_ERR(vma); /* maybe ... */
- if (!IS_ERR(vma) && mode != MPOL_NOOP)
- err = mbind_range(mm, start, end, new);
+ if (IS_ERR(vma))
+ goto mpol_out_unlock;

- if (!err) {
- int nr_failed = 0;
+ if (mode != MPOL_NOOP) {
+ err = mbind_range(mm, start, end, new);
+ if (err)
+ goto mpol_out_unlock;
+ }

- if (!list_empty(&pagelist)) {
- if (flags & MPOL_MF_LAZY)
- nr_failed = migrate_pages_unmap_only(&pagelist);
- else {
- nr_failed = migrate_pages(&pagelist, new_vma_page,
- (unsigned long)vma,
- false, true);
- }
- if (nr_failed)
- putback_lru_pages(&pagelist);
+ if (!list_empty(&pagelist)) {
+ if (flags & MPOL_MF_LAZY)
+ nr_failed = migrate_pages_unmap_only(&pagelist);
+ else {
+ nr_failed = migrate_pages(&pagelist, new_vma_page,
+ (unsigned long)vma,
+ false, true);
}
+ }

- if (nr_failed && (flags & MPOL_MF_STRICT))
- err = -EIO;
- } else
- putback_lru_pages(&pagelist);
+ if (nr_failed && (flags & MPOL_MF_STRICT))
+ err = -EIO;
+
+ putback_lru_pages(&pagelist);

+mpol_out_unlock:
up_write(&mm->mmap_sem);
- mpol_out:
+mpol_out:
mpol_put(new);
return err;
}



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