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2b729fe7f3
This reverts commit a49e4629b5
("cpuset: Make cpuset hotplug synchronous") as
it may deadlock with cpu hotplug path.
Link: http://lkml.kernel.org/r/F0388D99-84D7-453B-9B6B-EEFF0E7BE4CC@lca.pw
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Prateek Sood <prsood@codeaurora.org>
285 lines
7.3 KiB
C
285 lines
7.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#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/sched/topology.h>
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#include <linux/sched/task.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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/*
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* Static branch rewrites can happen in an arbitrary order for a given
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* key. In code paths where we need to loop with read_mems_allowed_begin() and
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* read_mems_allowed_retry() to get a consistent view of mems_allowed, we need
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* to ensure that begin() always gets rewritten before retry() in the
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* disabled -> enabled transition. If not, then if local irqs are disabled
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* around the loop, we can deadlock since retry() would always be
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* comparing the latest value of the mems_allowed seqcount against 0 as
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* begin() still would see cpusets_enabled() as false. The enabled -> disabled
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* transition should happen in reverse order for the same reasons (want to stop
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* looking at real value of mems_allowed.sequence in retry() first).
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*/
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extern struct static_key_false cpusets_pre_enable_key;
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extern struct static_key_false cpusets_enabled_key;
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static inline bool cpusets_enabled(void)
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{
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return static_branch_unlikely(&cpusets_enabled_key);
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}
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static inline void cpuset_inc(void)
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{
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static_branch_inc_cpuslocked(&cpusets_pre_enable_key);
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static_branch_inc_cpuslocked(&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_branch_dec_cpuslocked(&cpusets_enabled_key);
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static_branch_dec_cpuslocked(&cpusets_pre_enable_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_force_rebuild(void);
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extern void cpuset_update_active_cpus(void);
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extern void cpuset_wait_for_hotplug(void);
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extern void cpuset_read_lock(void);
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extern void cpuset_read_unlock(void);
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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 bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
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static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
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{
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if (cpusets_enabled())
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return __cpuset_node_allowed(node, gfp_mask);
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return true;
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}
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static inline bool __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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static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
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{
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if (cpusets_enabled())
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return __cpuset_zone_allowed(z, gfp_mask);
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return true;
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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 bool 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 (!static_branch_unlikely(&cpusets_pre_enable_key))
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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 (!static_branch_unlikely(&cpusets_enabled_key))
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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_force_rebuild(void) { }
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static inline void cpuset_update_active_cpus(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_wait_for_hotplug(void) { }
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static inline void cpuset_read_lock(void) { }
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static inline void cpuset_read_unlock(void) { }
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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 bool cpuset_node_allowed(int node, gfp_t gfp_mask)
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{
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return true;
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}
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static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
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{
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return true;
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}
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static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
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{
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return true;
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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 bool current_cpuset_is_being_rebound(void)
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{
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return false;
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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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