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![Mel Gorman](/assets/img/avatar_default.png)
There is a seqcounter that protects against spurious allocation failures when a task is changing the allowed nodes in a cpuset. There is no need to check the seqcounter until a cpuset exists. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
248 lines
5.7 KiB
C
248 lines
5.7 KiB
C
#ifndef _LINUX_CPUSET_H
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#define _LINUX_CPUSET_H
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/*
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* cpuset interface
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*
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* Copyright (C) 2003 BULL SA
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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*/
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#include <linux/sched.h>
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#include <linux/cpumask.h>
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#include <linux/nodemask.h>
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#include <linux/mm.h>
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#include <linux/jump_label.h>
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#ifdef CONFIG_CPUSETS
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extern struct static_key cpusets_enabled_key;
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static inline bool cpusets_enabled(void)
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{
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return static_key_false(&cpusets_enabled_key);
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}
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static inline int nr_cpusets(void)
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{
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/* jump label reference count + the top-level cpuset */
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return static_key_count(&cpusets_enabled_key) + 1;
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}
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static inline void cpuset_inc(void)
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{
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static_key_slow_inc(&cpusets_enabled_key);
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}
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static inline void cpuset_dec(void)
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{
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static_key_slow_dec(&cpusets_enabled_key);
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}
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extern int cpuset_init(void);
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extern void cpuset_init_smp(void);
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extern void cpuset_update_active_cpus(bool cpu_online);
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extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
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extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
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extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
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#define cpuset_current_mems_allowed (current->mems_allowed)
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void cpuset_init_current_mems_allowed(void);
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int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
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extern int __cpuset_node_allowed(int node, gfp_t gfp_mask);
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static inline int cpuset_node_allowed(int node, gfp_t gfp_mask)
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{
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return nr_cpusets() <= 1 || __cpuset_node_allowed(node, gfp_mask);
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}
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static inline int cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
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{
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return cpuset_node_allowed(zone_to_nid(z), gfp_mask);
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}
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extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
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const struct task_struct *tsk2);
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#define cpuset_memory_pressure_bump() \
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do { \
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if (cpuset_memory_pressure_enabled) \
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__cpuset_memory_pressure_bump(); \
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} while (0)
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extern int cpuset_memory_pressure_enabled;
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extern void __cpuset_memory_pressure_bump(void);
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extern void cpuset_task_status_allowed(struct seq_file *m,
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struct task_struct *task);
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extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
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struct pid *pid, struct task_struct *tsk);
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extern int cpuset_mem_spread_node(void);
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extern int cpuset_slab_spread_node(void);
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static inline int cpuset_do_page_mem_spread(void)
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{
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return task_spread_page(current);
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}
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static inline int cpuset_do_slab_mem_spread(void)
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{
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return task_spread_slab(current);
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}
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extern int current_cpuset_is_being_rebound(void);
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extern void rebuild_sched_domains(void);
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extern void cpuset_print_current_mems_allowed(void);
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/*
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* read_mems_allowed_begin is required when making decisions involving
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* mems_allowed such as during page allocation. mems_allowed can be updated in
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* parallel and depending on the new value an operation can fail potentially
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* causing process failure. A retry loop with read_mems_allowed_begin and
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* read_mems_allowed_retry prevents these artificial failures.
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*/
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static inline unsigned int read_mems_allowed_begin(void)
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{
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if (!cpusets_enabled())
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return 0;
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return read_seqcount_begin(¤t->mems_allowed_seq);
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}
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/*
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* If this returns true, the operation that took place after
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* read_mems_allowed_begin may have failed artificially due to a concurrent
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* update of mems_allowed. It is up to the caller to retry the operation if
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* appropriate.
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*/
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static inline bool read_mems_allowed_retry(unsigned int seq)
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{
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if (!cpusets_enabled())
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return false;
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return read_seqcount_retry(¤t->mems_allowed_seq, seq);
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}
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static inline void set_mems_allowed(nodemask_t nodemask)
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{
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unsigned long flags;
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task_lock(current);
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local_irq_save(flags);
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write_seqcount_begin(¤t->mems_allowed_seq);
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current->mems_allowed = nodemask;
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write_seqcount_end(¤t->mems_allowed_seq);
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local_irq_restore(flags);
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task_unlock(current);
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}
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#else /* !CONFIG_CPUSETS */
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static inline bool cpusets_enabled(void) { return false; }
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static inline int cpuset_init(void) { return 0; }
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static inline void cpuset_init_smp(void) {}
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static inline void cpuset_update_active_cpus(bool cpu_online)
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{
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partition_sched_domains(1, NULL, NULL);
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}
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static inline void cpuset_cpus_allowed(struct task_struct *p,
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struct cpumask *mask)
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{
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cpumask_copy(mask, cpu_possible_mask);
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}
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static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
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{
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}
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static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
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{
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return node_possible_map;
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}
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#define cpuset_current_mems_allowed (node_states[N_MEMORY])
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static inline void cpuset_init_current_mems_allowed(void) {}
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static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
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{
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return 1;
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}
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static inline int cpuset_node_allowed(int node, gfp_t gfp_mask)
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{
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return 1;
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}
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static inline int cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
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{
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return 1;
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}
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static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
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const struct task_struct *tsk2)
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{
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return 1;
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}
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static inline void cpuset_memory_pressure_bump(void) {}
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static inline void cpuset_task_status_allowed(struct seq_file *m,
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struct task_struct *task)
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{
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}
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static inline int cpuset_mem_spread_node(void)
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{
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return 0;
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}
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static inline int cpuset_slab_spread_node(void)
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{
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return 0;
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}
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static inline int cpuset_do_page_mem_spread(void)
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{
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return 0;
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}
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static inline int cpuset_do_slab_mem_spread(void)
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{
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return 0;
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}
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static inline int current_cpuset_is_being_rebound(void)
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{
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return 0;
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}
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static inline void rebuild_sched_domains(void)
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{
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partition_sched_domains(1, NULL, NULL);
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}
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static inline void cpuset_print_current_mems_allowed(void)
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{
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}
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static inline void set_mems_allowed(nodemask_t nodemask)
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{
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}
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static inline unsigned int read_mems_allowed_begin(void)
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{
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return 0;
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}
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static inline bool read_mems_allowed_retry(unsigned int seq)
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{
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return false;
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}
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#endif /* !CONFIG_CPUSETS */
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#endif /* _LINUX_CPUSET_H */
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