![Paul Jackson](/assets/img/avatar_default.png)
Fix more of longstanding bug in cpuset/mempolicy interaction. NUMA mempolicies (mm/mempolicy.c) are constrained by the current tasks cpuset to just the Memory Nodes allowed by that cpuset. The kernel maintains internal state for each mempolicy, tracking what nodes are used for the MPOL_INTERLEAVE, MPOL_BIND or MPOL_PREFERRED policies. When a tasks cpuset memory placement changes, whether because the cpuset changed, or because the task was attached to a different cpuset, then the tasks mempolicies have to be rebound to the new cpuset placement, so as to preserve the cpuset-relative numbering of the nodes in that policy. An earlier fix handled such mempolicy rebinding for mempolicies attached to a task. This fix rebinds mempolicies attached to vma's (address ranges in a tasks address space.) Due to the need to hold the task->mm->mmap_sem semaphore while updating vma's, the rebinding of vma mempolicies has to be done when the cpuset memory placement is changed, at which time mmap_sem can be safely acquired. The tasks mempolicy is rebound later, when the task next attempts to allocate memory and notices that its task->cpuset_mems_generation is out-of-date with its cpusets mems_generation. Because walking the tasklist to find all tasks attached to a changing cpuset requires holding tasklist_lock, a spinlock, one cannot update the vma's of the affected tasks while doing the tasklist scan. In general, one cannot acquire a semaphore (which can sleep) while already holding a spinlock (such as tasklist_lock). So a list of mm references has to be built up during the tasklist scan, then the tasklist lock dropped, then for each mm, its mmap_sem acquired, and the vma's in that mm rebound. Once the tasklist lock is dropped, affected tasks may fork new tasks, before their mm's are rebound. A kernel global 'cpuset_being_rebound' is set to point to the cpuset being rebound (there can only be one; cpuset modifications are done under a global 'manage_sem' semaphore), and the mpol_copy code that is used to copy a tasks mempolicies during fork catches such forking tasks, and ensures their children are also rebound. When a task is moved to a different cpuset, it is easier, as there is only one task involved. It's mm->vma's are scanned, using the same mpol_rebind_policy() as used above. It may happen that both the mpol_copy hook and the update done via the tasklist scan update the same mm twice. This is ok, as the mempolicies of each vma in an mm keep track of what mems_allowed they are relative to, and safely no-op a second request to rebind to the same nodes. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
275 lines
6.6 KiB
C
275 lines
6.6 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/config.h>
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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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#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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static inline void mpol_shared_policy_init(struct shared_policy *info)
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{
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info->root = RB_ROOT;
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spin_lock_init(&info->lock);
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}
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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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#define set_cpuset_being_rebound(x) (cpuset_being_rebound = (x))
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#ifdef CONFIG_CPUSET
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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);
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extern int policy_zone;
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static inline void check_highest_zone(int k)
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{
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if (k > policy_zone)
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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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{
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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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#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)
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{
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return NODE_DATA(0)->node_zonelists + gfp_zone(GFP_HIGHUSER);
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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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