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505970b96e
The problem, reported in: http://bugzilla.kernel.org/show_bug.cgi?id=5859 and by various other email messages and lkml posts is that the cpuset hook in the oom (out of memory) code can try to take a cpuset semaphore while holding the tasklist_lock (a spinlock). One must not sleep while holding a spinlock. The fix seems easy enough - move the cpuset semaphore region outside the tasklist_lock region. This required a few lines of mechanism to implement. The oom code where the locking needs to be changed does not have access to the cpuset locks, which are internal to kernel/cpuset.c only. So I provided a couple more cpuset interface routines, available to the rest of the kernel, which simple take and drop the lock needed here (cpusets callback_sem). Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
105 lines
2.8 KiB
C
105 lines
2.8 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 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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#ifdef CONFIG_CPUSETS
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extern int number_of_cpusets; /* How many cpusets are defined in system? */
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extern int cpuset_init_early(void);
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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_fork(struct task_struct *p);
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extern void cpuset_exit(struct task_struct *p);
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extern cpumask_t cpuset_cpus_allowed(struct task_struct *p);
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extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
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void cpuset_init_current_mems_allowed(void);
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void cpuset_update_task_memory_state(void);
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#define cpuset_nodes_subset_current_mems_allowed(nodes) \
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nodes_subset((nodes), current->mems_allowed)
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int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl);
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extern int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask);
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static int inline cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
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{
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return number_of_cpusets <= 1 || __cpuset_zone_allowed(z, gfp_mask);
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}
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extern int cpuset_excl_nodes_overlap(const struct task_struct *p);
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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 struct file_operations proc_cpuset_operations;
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extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer);
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extern void cpuset_lock(void);
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extern void cpuset_unlock(void);
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#else /* !CONFIG_CPUSETS */
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static inline int cpuset_init_early(void) { return 0; }
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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_fork(struct task_struct *p) {}
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static inline void cpuset_exit(struct task_struct *p) {}
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static inline cpumask_t cpuset_cpus_allowed(struct task_struct *p)
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{
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return cpu_possible_map;
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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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static inline void cpuset_init_current_mems_allowed(void) {}
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static inline void cpuset_update_task_memory_state(void) {}
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#define cpuset_nodes_subset_current_mems_allowed(nodes) (1)
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static inline int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl)
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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_excl_nodes_overlap(const struct task_struct *p)
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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 char *cpuset_task_status_allowed(struct task_struct *task,
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char *buffer)
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{
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return buffer;
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}
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static inline void cpuset_lock(void) {}
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static inline void cpuset_unlock(void) {}
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#endif /* !CONFIG_CPUSETS */
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#endif /* _LINUX_CPUSET_H */
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