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![Lee Schermerhorn](/assets/img/avatar_default.png)
This patch proposes fixes to the reference counting of memory policy in the page allocation paths and in show_numa_map(). Extracted from my "Memory Policy Cleanups and Enhancements" series as stand-alone. Shared policy lookup [shmem] has always added a reference to the policy, but this was never unrefed after page allocation or after formatting the numa map data. Default system policy should not require additional ref counting, nor should the current task's task policy. However, show_numa_map() calls get_vma_policy() to examine what may be [likely is] another task's policy. The latter case needs protection against freeing of the policy. This patch adds a reference count to a mempolicy returned by get_vma_policy() when the policy is a vma policy or another task's mempolicy. Again, shared policy is already reference counted on lookup. A matching "unref" [__mpol_free()] is performed in alloc_page_vma() for shared and vma policies, and in show_numa_map() for shared and another task's mempolicy. We can call __mpol_free() directly, saving an admittedly inexpensive inline NULL test, because we know we have a non-NULL policy. Handling policy ref counts for hugepages is a bit trickier. huge_zonelist() returns a zone list that might come from a shared or vma 'BIND policy. In this case, we should hold the reference until after the huge page allocation in dequeue_hugepage(). The patch modifies huge_zonelist() to return a pointer to the mempolicy if it needs to be unref'd after allocation. Kernel Build [16cpu, 32GB, ia64] - average of 10 runs: w/o patch w/ refcount patch Avg Std Devn Avg Std Devn Real: 100.59 0.38 100.63 0.43 User: 1209.60 0.37 1209.91 0.31 System: 81.52 0.42 81.64 0.34 Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Andi Kleen <ak@suse.de> Cc: Christoph Lameter <clameter@sgi.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
277 lines
6.9 KiB
C
277 lines
6.9 KiB
C
#ifndef _LINUX_MEMPOLICY_H
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#define _LINUX_MEMPOLICY_H 1
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#include <linux/errno.h>
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/*
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* NUMA memory policies for Linux.
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* Copyright 2003,2004 Andi Kleen SuSE Labs
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*/
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/* Policies */
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#define MPOL_DEFAULT 0
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#define MPOL_PREFERRED 1
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#define MPOL_BIND 2
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#define MPOL_INTERLEAVE 3
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#define MPOL_MAX MPOL_INTERLEAVE
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/* Flags for get_mem_policy */
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#define MPOL_F_NODE (1<<0) /* return next IL mode instead of node mask */
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#define MPOL_F_ADDR (1<<1) /* look up vma using address */
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/* Flags for mbind */
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#define MPOL_MF_STRICT (1<<0) /* Verify existing pages in the mapping */
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#define MPOL_MF_MOVE (1<<1) /* Move pages owned by this process to conform to mapping */
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#define MPOL_MF_MOVE_ALL (1<<2) /* Move every page to conform to mapping */
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#define MPOL_MF_INTERNAL (1<<3) /* Internal flags start here */
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#ifdef __KERNEL__
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#include <linux/mmzone.h>
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#include <linux/slab.h>
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#include <linux/rbtree.h>
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#include <linux/spinlock.h>
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#include <linux/nodemask.h>
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struct vm_area_struct;
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struct mm_struct;
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#ifdef CONFIG_NUMA
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/*
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* Describe a memory policy.
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*
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* A mempolicy can be either associated with a process or with a VMA.
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* For VMA related allocations the VMA policy is preferred, otherwise
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* the process policy is used. Interrupts ignore the memory policy
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* of the current process.
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*
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* Locking policy for interlave:
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* In process context there is no locking because only the process accesses
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* its own state. All vma manipulation is somewhat protected by a down_read on
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* mmap_sem.
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*
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* Freeing policy:
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* When policy is MPOL_BIND v.zonelist is kmalloc'ed and must be kfree'd.
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* All other policies don't have any external state. mpol_free() handles this.
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*
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* Copying policy objects:
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* For MPOL_BIND the zonelist must be always duplicated. mpol_clone() does this.
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*/
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struct mempolicy {
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atomic_t refcnt;
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short policy; /* See MPOL_* above */
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union {
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struct zonelist *zonelist; /* bind */
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short preferred_node; /* preferred */
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nodemask_t nodes; /* interleave */
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/* undefined for default */
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} v;
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nodemask_t cpuset_mems_allowed; /* mempolicy relative to these nodes */
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};
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/*
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* Support for managing mempolicy data objects (clone, copy, destroy)
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* The default fast path of a NULL MPOL_DEFAULT policy is always inlined.
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*/
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extern void __mpol_free(struct mempolicy *pol);
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static inline void mpol_free(struct mempolicy *pol)
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{
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if (pol)
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__mpol_free(pol);
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}
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extern struct mempolicy *__mpol_copy(struct mempolicy *pol);
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static inline struct mempolicy *mpol_copy(struct mempolicy *pol)
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{
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if (pol)
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pol = __mpol_copy(pol);
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return pol;
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}
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#define vma_policy(vma) ((vma)->vm_policy)
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#define vma_set_policy(vma, pol) ((vma)->vm_policy = (pol))
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static inline void mpol_get(struct mempolicy *pol)
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{
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if (pol)
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atomic_inc(&pol->refcnt);
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}
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extern int __mpol_equal(struct mempolicy *a, struct mempolicy *b);
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static inline int mpol_equal(struct mempolicy *a, struct mempolicy *b)
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{
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if (a == b)
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return 1;
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return __mpol_equal(a, b);
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}
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#define vma_mpol_equal(a,b) mpol_equal(vma_policy(a), vma_policy(b))
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/* Could later add inheritance of the process policy here. */
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#define mpol_set_vma_default(vma) ((vma)->vm_policy = NULL)
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/*
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* Tree of shared policies for a shared memory region.
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* Maintain the policies in a pseudo mm that contains vmas. The vmas
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* carry the policy. As a special twist the pseudo mm is indexed in pages, not
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* bytes, so that we can work with shared memory segments bigger than
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* unsigned long.
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*/
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struct sp_node {
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struct rb_node nd;
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unsigned long start, end;
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struct mempolicy *policy;
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};
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struct shared_policy {
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struct rb_root root;
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spinlock_t lock;
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};
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void mpol_shared_policy_init(struct shared_policy *info, int policy,
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nodemask_t *nodes);
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int mpol_set_shared_policy(struct shared_policy *info,
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struct vm_area_struct *vma,
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struct mempolicy *new);
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void mpol_free_shared_policy(struct shared_policy *p);
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struct mempolicy *mpol_shared_policy_lookup(struct shared_policy *sp,
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unsigned long idx);
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extern void numa_default_policy(void);
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extern void numa_policy_init(void);
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extern void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *new);
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extern void mpol_rebind_task(struct task_struct *tsk,
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const nodemask_t *new);
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extern void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new);
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extern void mpol_fix_fork_child_flag(struct task_struct *p);
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#define set_cpuset_being_rebound(x) (cpuset_being_rebound = (x))
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#ifdef CONFIG_CPUSETS
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#define current_cpuset_is_being_rebound() \
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(cpuset_being_rebound == current->cpuset)
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#else
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#define current_cpuset_is_being_rebound() 0
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#endif
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extern struct mempolicy default_policy;
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extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
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unsigned long addr, gfp_t gfp_flags, struct mempolicy **mpol);
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extern unsigned slab_node(struct mempolicy *policy);
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extern enum zone_type policy_zone;
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static inline void check_highest_zone(enum zone_type k)
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{
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if (k > policy_zone && k != ZONE_MOVABLE)
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policy_zone = k;
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}
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int do_migrate_pages(struct mm_struct *mm,
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const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags);
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extern void *cpuset_being_rebound; /* Trigger mpol_copy vma rebind */
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#else
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struct mempolicy {};
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static inline int mpol_equal(struct mempolicy *a, struct mempolicy *b)
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{
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return 1;
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}
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#define vma_mpol_equal(a,b) 1
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#define mpol_set_vma_default(vma) do {} while(0)
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static inline void mpol_free(struct mempolicy *p)
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{
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}
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static inline void mpol_get(struct mempolicy *pol)
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{
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}
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static inline struct mempolicy *mpol_copy(struct mempolicy *old)
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{
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return NULL;
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}
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struct shared_policy {};
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static inline int mpol_set_shared_policy(struct shared_policy *info,
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struct vm_area_struct *vma,
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struct mempolicy *new)
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{
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return -EINVAL;
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}
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static inline void mpol_shared_policy_init(struct shared_policy *info,
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int policy, nodemask_t *nodes)
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{
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}
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static inline void mpol_free_shared_policy(struct shared_policy *p)
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{
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}
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static inline struct mempolicy *
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mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
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{
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return NULL;
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}
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#define vma_policy(vma) NULL
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#define vma_set_policy(vma, pol) do {} while(0)
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static inline void numa_policy_init(void)
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{
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}
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static inline void numa_default_policy(void)
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{
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}
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static inline void mpol_rebind_policy(struct mempolicy *pol,
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const nodemask_t *new)
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{
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}
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static inline void mpol_rebind_task(struct task_struct *tsk,
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const nodemask_t *new)
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{
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}
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static inline void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
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{
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}
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static inline void mpol_fix_fork_child_flag(struct task_struct *p)
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{
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}
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#define set_cpuset_being_rebound(x) do {} while (0)
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static inline struct zonelist *huge_zonelist(struct vm_area_struct *vma,
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unsigned long addr, gfp_t gfp_flags, struct mempolicy **mpol)
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{
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return NODE_DATA(0)->node_zonelists + gfp_zone(gfp_flags);
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}
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static inline int do_migrate_pages(struct mm_struct *mm,
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const nodemask_t *from_nodes,
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const nodemask_t *to_nodes, int flags)
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{
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return 0;
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}
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static inline void check_highest_zone(int k)
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{
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}
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#endif /* CONFIG_NUMA */
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#endif /* __KERNEL__ */
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#endif
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