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![Vladimir Davydov](/assets/img/avatar_default.png)
Current cpuset API for checking if a zone/node is allowed to allocate
from looks rather awkward. We have hardwall and softwall versions of
cpuset_node_allowed with the softwall version doing literally the same
as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags.
If it isn't, the softwall version may check the given node against the
enclosing hardwall cpuset, which it needs to take the callback lock to
do.
Such a distinction was introduced by commit 02a0e53d82
("cpuset:
rework cpuset_zone_allowed api"). Before, we had the only version with
the __GFP_HARDWALL flag determining its behavior. The purpose of the
commit was to avoid sleep-in-atomic bugs when someone would mistakenly
call the function without the __GFP_HARDWALL flag for an atomic
allocation. The suffixes introduced were intended to make the callers
think before using the function.
However, since the callback lock was converted from mutex to spinlock by
the previous patch, the softwall check function cannot sleep, and these
precautions are no longer necessary.
So let's simplify the API back to the single check.
Suggested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
242 lines
5.7 KiB
C
242 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_task_mems_allowed(struct task_struct *p);
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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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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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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_task_mems_allowed(struct task_struct *p)
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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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