aboutsummaryrefslogtreecommitdiffstats
path: root/mm/mempolicy.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c79
1 files changed, 70 insertions, 9 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index bb54b88c3d5a..3d6ac9505d07 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1077,21 +1077,37 @@ asmlinkage long compat_sys_mbind(compat_ulong_t start, compat_ulong_t len,
#endif
-/* Return effective policy for a VMA */
+/*
+ * get_vma_policy(@task, @vma, @addr)
+ * @task - task for fallback if vma policy == default
+ * @vma - virtual memory area whose policy is sought
+ * @addr - address in @vma for shared policy lookup
+ *
+ * Returns effective policy for a VMA at specified address.
+ * Falls back to @task or system default policy, as necessary.
+ * Returned policy has extra reference count if shared, vma,
+ * or some other task's policy [show_numa_maps() can pass
+ * @task != current]. It is the caller's responsibility to
+ * free the reference in these cases.
+ */
static struct mempolicy * get_vma_policy(struct task_struct *task,
struct vm_area_struct *vma, unsigned long addr)
{
struct mempolicy *pol = task->mempolicy;
+ int shared_pol = 0;
if (vma) {
- if (vma->vm_ops && vma->vm_ops->get_policy)
+ if (vma->vm_ops && vma->vm_ops->get_policy) {
pol = vma->vm_ops->get_policy(vma, addr);
- else if (vma->vm_policy &&
+ shared_pol = 1; /* if pol non-NULL, add ref below */
+ } else if (vma->vm_policy &&
vma->vm_policy->policy != MPOL_DEFAULT)
pol = vma->vm_policy;
}
if (!pol)
pol = &default_policy;
+ else if (!shared_pol && pol != current->mempolicy)
+ mpol_get(pol); /* vma or other task's policy */
return pol;
}
@@ -1207,19 +1223,45 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
}
#ifdef CONFIG_HUGETLBFS
-/* Return a zonelist suitable for a huge page allocation. */
+/*
+ * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
+ * @vma = virtual memory area whose policy is sought
+ * @addr = address in @vma for shared policy lookup and interleave policy
+ * @gfp_flags = for requested zone
+ * @mpol = pointer to mempolicy pointer for reference counted 'BIND policy
+ *
+ * Returns a zonelist suitable for a huge page allocation.
+ * If the effective policy is 'BIND, returns pointer to policy's zonelist.
+ * If it is also a policy for which get_vma_policy() returns an extra
+ * reference, we must hold that reference until after allocation.
+ * In that case, return policy via @mpol so hugetlb allocation can drop
+ * the reference. For non-'BIND referenced policies, we can/do drop the
+ * reference here, so the caller doesn't need to know about the special case
+ * for default and current task policy.
+ */
struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
- gfp_t gfp_flags)
+ gfp_t gfp_flags, struct mempolicy **mpol)
{
struct mempolicy *pol = get_vma_policy(current, vma, addr);
+ struct zonelist *zl;
+ *mpol = NULL; /* probably no unref needed */
if (pol->policy == MPOL_INTERLEAVE) {
unsigned nid;
nid = interleave_nid(pol, vma, addr, HPAGE_SHIFT);
+ __mpol_free(pol); /* finished with pol */
return NODE_DATA(nid)->node_zonelists + gfp_zone(gfp_flags);
}
- return zonelist_policy(GFP_HIGHUSER, pol);
+
+ zl = zonelist_policy(GFP_HIGHUSER, pol);
+ if (unlikely(pol != &default_policy && pol != current->mempolicy)) {
+ if (pol->policy != MPOL_BIND)
+ __mpol_free(pol); /* finished with pol */
+ else
+ *mpol = pol; /* unref needed after allocation */
+ }
+ return zl;
}
#endif
@@ -1264,6 +1306,7 @@ struct page *
alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
{
struct mempolicy *pol = get_vma_policy(current, vma, addr);
+ struct zonelist *zl;
cpuset_update_task_memory_state();
@@ -1273,7 +1316,19 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
nid = interleave_nid(pol, vma, addr, PAGE_SHIFT);
return alloc_page_interleave(gfp, 0, nid);
}
- return __alloc_pages(gfp, 0, zonelist_policy(gfp, pol));
+ zl = zonelist_policy(gfp, pol);
+ if (pol != &default_policy && pol != current->mempolicy) {
+ /*
+ * slow path: ref counted policy -- shared or vma
+ */
+ struct page *page = __alloc_pages(gfp, 0, zl);
+ __mpol_free(pol);
+ return page;
+ }
+ /*
+ * fast path: default or task policy
+ */
+ return __alloc_pages(gfp, 0, zl);
}
/**
@@ -1872,6 +1927,7 @@ int show_numa_map(struct seq_file *m, void *v)
struct numa_maps *md;
struct file *file = vma->vm_file;
struct mm_struct *mm = vma->vm_mm;
+ struct mempolicy *pol;
int n;
char buffer[50];
@@ -1882,8 +1938,13 @@ int show_numa_map(struct seq_file *m, void *v)
if (!md)
return 0;
- mpol_to_str(buffer, sizeof(buffer),
- get_vma_policy(priv->task, vma, vma->vm_start));
+ pol = get_vma_policy(priv->task, vma, vma->vm_start);
+ mpol_to_str(buffer, sizeof(buffer), pol);
+ /*
+ * unref shared or other task's mempolicy
+ */
+ if (pol != &default_policy && pol != current->mempolicy)
+ __mpol_free(pol);
seq_printf(m, "%08lx %s", vma->vm_start, buffer);

Privacy Policy