diff options
| -rw-r--r-- | include/linux/cpuset.h | 6 | ||||
| -rw-r--r-- | kernel/cpuset.c | 33 | ||||
| -rw-r--r-- | mm/oom_kill.c | 3 |
3 files changed, 37 insertions, 5 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index c472f972bd6..3bc60692711 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -48,6 +48,9 @@ extern void __cpuset_memory_pressure_bump(void); extern struct file_operations proc_cpuset_operations; extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer); +extern void cpuset_lock(void); +extern void cpuset_unlock(void); + #else /* !CONFIG_CPUSETS */ static inline int cpuset_init_early(void) { return 0; } @@ -93,6 +96,9 @@ static inline char *cpuset_task_status_allowed(struct task_struct *task, return buffer; } +static inline void cpuset_lock(void) {} +static inline void cpuset_unlock(void) {} + #endif /* !CONFIG_CPUSETS */ #endif /* _LINUX_CPUSET_H */ diff --git a/kernel/cpuset.c b/kernel/cpuset.c index d4b6bd7d74e..fe2f71f92ae 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2150,6 +2150,33 @@ int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask) } /** + * cpuset_lock - lock out any changes to cpuset structures + * + * The out of memory (oom) code needs to lock down cpusets + * from being changed while it scans the tasklist looking for a + * task in an overlapping cpuset. Expose callback_sem via this + * cpuset_lock() routine, so the oom code can lock it, before + * locking the task list. The tasklist_lock is a spinlock, so + * must be taken inside callback_sem. + */ + +void cpuset_lock(void) +{ + down(&callback_sem); +} + +/** + * cpuset_unlock - release lock on cpuset changes + * + * Undo the lock taken in a previous cpuset_lock() call. + */ + +void cpuset_unlock(void) +{ + up(&callback_sem); +} + +/** * cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors? * @p: pointer to task_struct of some other task. * @@ -2158,7 +2185,7 @@ int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask) * determine if task @p's memory usage might impact the memory * available to the current task. * - * Acquires callback_sem - not suitable for calling from a fast path. + * Call while holding callback_sem. **/ int cpuset_excl_nodes_overlap(const struct task_struct *p) @@ -2166,8 +2193,6 @@ int cpuset_excl_nodes_overlap(const struct task_struct *p) const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */ int overlap = 0; /* do cpusets overlap? */ - down(&callback_sem); - task_lock(current); if (current->flags & PF_EXITING) { task_unlock(current); @@ -2186,8 +2211,6 @@ int cpuset_excl_nodes_overlap(const struct task_struct *p) overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed); done: - up(&callback_sem); - return overlap; } diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 4748b906aff..14bd4ec7959 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -274,6 +274,7 @@ void out_of_memory(gfp_t gfp_mask, int order) show_mem(); } + cpuset_lock(); read_lock(&tasklist_lock); retry: p = select_bad_process(); @@ -284,6 +285,7 @@ retry: /* Found nothing?!?! Either we hang forever, or we panic. */ if (!p) { read_unlock(&tasklist_lock); + cpuset_unlock(); panic("Out of memory and no killable processes...\n"); } @@ -293,6 +295,7 @@ retry: out: read_unlock(&tasklist_lock); + cpuset_unlock(); if (mm) mmput(mm); |