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Subject[RFC][PATCH 20/26] mm, mpol: Introduce vma_dup_policy()
In preparation of other changes, pull some code duplication in a
common function so that we can later extend its behaviour without
having to touch all these sites.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/mempolicy.h | 3 +++
kernel/fork.c | 9 +++------
mm/mempolicy.c | 11 +++++++++++
mm/mmap.c | 17 +++++------------
4 files changed, 22 insertions(+), 18 deletions(-)
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -168,6 +168,8 @@ static inline struct mempolicy *mpol_dup
#define vma_policy(vma) ((vma)->vm_policy)
#define vma_set_policy(vma, pol) ((vma)->vm_policy = (pol))

+extern int vma_dup_policy(struct vm_area_struct *new, struct vm_area_struct *old);
+
static inline void mpol_get(struct mempolicy *pol)
{
if (pol)
@@ -311,6 +313,7 @@ mpol_shared_policy_lookup(struct shared_

#define vma_policy(vma) NULL
#define vma_set_policy(vma, pol) do {} while(0)
+#define vma_dup_policy(new, old) (0)

static inline void numa_policy_init(void)
{
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -315,7 +315,6 @@ static int dup_mmap(struct mm_struct *mm
struct rb_node **rb_link, *rb_parent;
int retval;
unsigned long charge;
- struct mempolicy *pol;

down_write(&oldmm->mmap_sem);
flush_cache_dup_mm(oldmm);
@@ -365,11 +364,9 @@ static int dup_mmap(struct mm_struct *mm
goto fail_nomem;
*tmp = *mpnt;
INIT_LIST_HEAD(&tmp->anon_vma_chain);
- pol = mpol_dup(vma_policy(mpnt));
- retval = PTR_ERR(pol);
- if (IS_ERR(pol))
+ retval = vma_dup_policy(tmp, mpnt);
+ if (retval)
goto fail_nomem_policy;
- vma_set_policy(tmp, pol);
tmp->vm_mm = mm;
if (anon_vma_fork(tmp, mpnt))
goto fail_nomem_anon_vma_fork;
@@ -431,7 +428,7 @@ static int dup_mmap(struct mm_struct *mm
up_write(&oldmm->mmap_sem);
return retval;
fail_nomem_anon_vma_fork:
- mpol_put(pol);
+ mpol_put(vma_policy(tmp));
fail_nomem_policy:
kmem_cache_free(vm_area_cachep, tmp);
fail_nomem:
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1971,6 +1971,17 @@ struct mempolicy *__mpol_dup(struct memp
return new;
}

+int vma_dup_policy(struct vm_area_struct *new, struct vm_area_struct *old)
+{
+ struct mempolicy *mpol;
+
+ mpol = mpol_dup(vma_policy(old));
+ if (IS_ERR(mpol))
+ return PTR_ERR(mpol);
+ vma_set_policy(new, mpol);
+ return 0;
+}
+
/*
* If *frompol needs [has] an extra ref, copy *frompol to *tompol ,
* eliminate the * MPOL_F_* flags that require conditional ref and
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1935,7 +1935,6 @@ detach_vmas_to_be_unmapped(struct mm_str
static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
unsigned long addr, int new_below)
{
- struct mempolicy *pol;
struct vm_area_struct *new;
int err = -ENOMEM;

@@ -1959,12 +1958,9 @@ static int __split_vma(struct mm_struct
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
}

- pol = mpol_dup(vma_policy(vma));
- if (IS_ERR(pol)) {
- err = PTR_ERR(pol);
+ err = vma_dup_policy(new, vma);
+ if (err)
goto out_free_vma;
- }
- vma_set_policy(new, pol);

if (anon_vma_clone(new, vma))
goto out_free_mpol;
@@ -1998,7 +1994,7 @@ static int __split_vma(struct mm_struct
}
unlink_anon_vmas(new);
out_free_mpol:
- mpol_put(pol);
+ mpol_put(new->vm_policy);
out_free_vma:
kmem_cache_free(vm_area_cachep, new);
out_err:
@@ -2331,7 +2327,6 @@ struct vm_area_struct *copy_vma(struct v
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *new_vma, *prev;
struct rb_node **rb_link, *rb_parent;
- struct mempolicy *pol;
bool faulted_in_anon_vma = true;

/*
@@ -2372,13 +2367,11 @@ struct vm_area_struct *copy_vma(struct v
new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (new_vma) {
*new_vma = *vma;
- pol = mpol_dup(vma_policy(vma));
- if (IS_ERR(pol))
+ if (vma_dup_policy(new_vma, vma))
goto out_free_vma;
INIT_LIST_HEAD(&new_vma->anon_vma_chain);
if (anon_vma_clone(new_vma, vma))
goto out_free_mempol;
- vma_set_policy(new_vma, pol);
new_vma->vm_start = addr;
new_vma->vm_end = addr + len;
new_vma->vm_pgoff = pgoff;
@@ -2399,7 +2392,7 @@ struct vm_area_struct *copy_vma(struct v
return new_vma;

out_free_mempol:
- mpol_put(pol);
+ mpol_put(new_vma->vm_policy);
out_free_vma:
kmem_cache_free(vm_area_cachep, new_vma);
return NULL;



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