mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Juri Lelli](/assets/img/avatar_default.png)
No synchronisation mechanism exists between the cpuset subsystem and calls to function __sched_setscheduler(). As such, it is possible that new root domains are created on the cpuset side while a deadline acceptance test is carried out in __sched_setscheduler(), leading to a potential oversell of CPU bandwidth. Grab cpuset_rwsem read lock from core scheduler, so to prevent situations such as the one described above from happening. The only exception is normalize_rt_tasks() which needs to work under tasklist_lock and can't therefore grab cpuset_rwsem. We are fine with this, as this function is only called by sysrq and, if that gets triggered, DEADLINE guarantees are already gone out of the window anyway. Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bristot@redhat.com Cc: claudio@evidence.eu.com Cc: lizefan@huawei.com Cc: longman@redhat.com Cc: luca.abeni@santannapisa.it Cc: mathieu.poirier@linaro.org Cc: rostedt@goodmis.org Cc: tj@kernel.org Cc: tommaso.cucinotta@santannapisa.it Link: https://lkml.kernel.org/r/20190719140000.31694-9-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
285 lines
7.3 KiB
C
285 lines
7.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_CPUSET_H
|
|
#define _LINUX_CPUSET_H
|
|
/*
|
|
* cpuset interface
|
|
*
|
|
* Copyright (C) 2003 BULL SA
|
|
* Copyright (C) 2004-2006 Silicon Graphics, Inc.
|
|
*
|
|
*/
|
|
|
|
#include <linux/sched.h>
|
|
#include <linux/sched/topology.h>
|
|
#include <linux/sched/task.h>
|
|
#include <linux/cpumask.h>
|
|
#include <linux/nodemask.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/jump_label.h>
|
|
|
|
#ifdef CONFIG_CPUSETS
|
|
|
|
/*
|
|
* Static branch rewrites can happen in an arbitrary order for a given
|
|
* key. In code paths where we need to loop with read_mems_allowed_begin() and
|
|
* read_mems_allowed_retry() to get a consistent view of mems_allowed, we need
|
|
* to ensure that begin() always gets rewritten before retry() in the
|
|
* disabled -> enabled transition. If not, then if local irqs are disabled
|
|
* around the loop, we can deadlock since retry() would always be
|
|
* comparing the latest value of the mems_allowed seqcount against 0 as
|
|
* begin() still would see cpusets_enabled() as false. The enabled -> disabled
|
|
* transition should happen in reverse order for the same reasons (want to stop
|
|
* looking at real value of mems_allowed.sequence in retry() first).
|
|
*/
|
|
extern struct static_key_false cpusets_pre_enable_key;
|
|
extern struct static_key_false cpusets_enabled_key;
|
|
static inline bool cpusets_enabled(void)
|
|
{
|
|
return static_branch_unlikely(&cpusets_enabled_key);
|
|
}
|
|
|
|
static inline void cpuset_inc(void)
|
|
{
|
|
static_branch_inc_cpuslocked(&cpusets_pre_enable_key);
|
|
static_branch_inc_cpuslocked(&cpusets_enabled_key);
|
|
}
|
|
|
|
static inline void cpuset_dec(void)
|
|
{
|
|
static_branch_dec_cpuslocked(&cpusets_enabled_key);
|
|
static_branch_dec_cpuslocked(&cpusets_pre_enable_key);
|
|
}
|
|
|
|
extern int cpuset_init(void);
|
|
extern void cpuset_init_smp(void);
|
|
extern void cpuset_force_rebuild(void);
|
|
extern void cpuset_update_active_cpus(void);
|
|
extern void cpuset_wait_for_hotplug(void);
|
|
extern void cpuset_read_lock(void);
|
|
extern void cpuset_read_unlock(void);
|
|
extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
|
|
extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
|
|
extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
|
|
#define cpuset_current_mems_allowed (current->mems_allowed)
|
|
void cpuset_init_current_mems_allowed(void);
|
|
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
|
|
|
|
extern bool __cpuset_node_allowed(int node, gfp_t gfp_mask);
|
|
|
|
static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
|
|
{
|
|
if (cpusets_enabled())
|
|
return __cpuset_node_allowed(node, gfp_mask);
|
|
return true;
|
|
}
|
|
|
|
static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
|
|
{
|
|
return __cpuset_node_allowed(zone_to_nid(z), gfp_mask);
|
|
}
|
|
|
|
static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
|
|
{
|
|
if (cpusets_enabled())
|
|
return __cpuset_zone_allowed(z, gfp_mask);
|
|
return true;
|
|
}
|
|
|
|
extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
|
|
const struct task_struct *tsk2);
|
|
|
|
#define cpuset_memory_pressure_bump() \
|
|
do { \
|
|
if (cpuset_memory_pressure_enabled) \
|
|
__cpuset_memory_pressure_bump(); \
|
|
} while (0)
|
|
extern int cpuset_memory_pressure_enabled;
|
|
extern void __cpuset_memory_pressure_bump(void);
|
|
|
|
extern void cpuset_task_status_allowed(struct seq_file *m,
|
|
struct task_struct *task);
|
|
extern int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
|
|
struct pid *pid, struct task_struct *tsk);
|
|
|
|
extern int cpuset_mem_spread_node(void);
|
|
extern int cpuset_slab_spread_node(void);
|
|
|
|
static inline int cpuset_do_page_mem_spread(void)
|
|
{
|
|
return task_spread_page(current);
|
|
}
|
|
|
|
static inline int cpuset_do_slab_mem_spread(void)
|
|
{
|
|
return task_spread_slab(current);
|
|
}
|
|
|
|
extern bool current_cpuset_is_being_rebound(void);
|
|
|
|
extern void rebuild_sched_domains(void);
|
|
|
|
extern void cpuset_print_current_mems_allowed(void);
|
|
|
|
/*
|
|
* read_mems_allowed_begin is required when making decisions involving
|
|
* mems_allowed such as during page allocation. mems_allowed can be updated in
|
|
* parallel and depending on the new value an operation can fail potentially
|
|
* causing process failure. A retry loop with read_mems_allowed_begin and
|
|
* read_mems_allowed_retry prevents these artificial failures.
|
|
*/
|
|
static inline unsigned int read_mems_allowed_begin(void)
|
|
{
|
|
if (!static_branch_unlikely(&cpusets_pre_enable_key))
|
|
return 0;
|
|
|
|
return read_seqcount_begin(¤t->mems_allowed_seq);
|
|
}
|
|
|
|
/*
|
|
* If this returns true, the operation that took place after
|
|
* read_mems_allowed_begin may have failed artificially due to a concurrent
|
|
* update of mems_allowed. It is up to the caller to retry the operation if
|
|
* appropriate.
|
|
*/
|
|
static inline bool read_mems_allowed_retry(unsigned int seq)
|
|
{
|
|
if (!static_branch_unlikely(&cpusets_enabled_key))
|
|
return false;
|
|
|
|
return read_seqcount_retry(¤t->mems_allowed_seq, seq);
|
|
}
|
|
|
|
static inline void set_mems_allowed(nodemask_t nodemask)
|
|
{
|
|
unsigned long flags;
|
|
|
|
task_lock(current);
|
|
local_irq_save(flags);
|
|
write_seqcount_begin(¤t->mems_allowed_seq);
|
|
current->mems_allowed = nodemask;
|
|
write_seqcount_end(¤t->mems_allowed_seq);
|
|
local_irq_restore(flags);
|
|
task_unlock(current);
|
|
}
|
|
|
|
#else /* !CONFIG_CPUSETS */
|
|
|
|
static inline bool cpusets_enabled(void) { return false; }
|
|
|
|
static inline int cpuset_init(void) { return 0; }
|
|
static inline void cpuset_init_smp(void) {}
|
|
|
|
static inline void cpuset_force_rebuild(void) { }
|
|
|
|
static inline void cpuset_update_active_cpus(void)
|
|
{
|
|
partition_sched_domains(1, NULL, NULL);
|
|
}
|
|
|
|
static inline void cpuset_wait_for_hotplug(void) { }
|
|
|
|
static inline void cpuset_read_lock(void) { }
|
|
static inline void cpuset_read_unlock(void) { }
|
|
|
|
static inline void cpuset_cpus_allowed(struct task_struct *p,
|
|
struct cpumask *mask)
|
|
{
|
|
cpumask_copy(mask, cpu_possible_mask);
|
|
}
|
|
|
|
static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
|
|
{
|
|
return node_possible_map;
|
|
}
|
|
|
|
#define cpuset_current_mems_allowed (node_states[N_MEMORY])
|
|
static inline void cpuset_init_current_mems_allowed(void) {}
|
|
|
|
static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static inline bool cpuset_node_allowed(int node, gfp_t gfp_mask)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
static inline bool __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
static inline bool cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
|
|
const struct task_struct *tsk2)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static inline void cpuset_memory_pressure_bump(void) {}
|
|
|
|
static inline void cpuset_task_status_allowed(struct seq_file *m,
|
|
struct task_struct *task)
|
|
{
|
|
}
|
|
|
|
static inline int cpuset_mem_spread_node(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int cpuset_slab_spread_node(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int cpuset_do_page_mem_spread(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int cpuset_do_slab_mem_spread(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline bool current_cpuset_is_being_rebound(void)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline void rebuild_sched_domains(void)
|
|
{
|
|
partition_sched_domains(1, NULL, NULL);
|
|
}
|
|
|
|
static inline void cpuset_print_current_mems_allowed(void)
|
|
{
|
|
}
|
|
|
|
static inline void set_mems_allowed(nodemask_t nodemask)
|
|
{
|
|
}
|
|
|
|
static inline unsigned int read_mems_allowed_begin(void)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline bool read_mems_allowed_retry(unsigned int seq)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
#endif /* !CONFIG_CPUSETS */
|
|
|
|
#endif /* _LINUX_CPUSET_H */
|