diff options
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 10131fdaff7..0b1712dba58 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -37,7 +37,7 @@ #include <linux/mempolicy.h> #include <linux/mm.h> #include <linux/memory.h> -#include <linux/module.h> +#include <linux/export.h> #include <linux/mount.h> #include <linux/namei.h> #include <linux/pagemap.h> @@ -123,6 +123,19 @@ static inline struct cpuset *task_cs(struct task_struct *task) struct cpuset, css); } +#ifdef CONFIG_NUMA +static inline bool task_has_mempolicy(struct task_struct *task) +{ + return task->mempolicy; +} +#else +static inline bool task_has_mempolicy(struct task_struct *task) +{ + return false; +} +#endif + + /* bits in struct cpuset flags field */ typedef enum { CS_CPU_EXCLUSIVE, @@ -949,6 +962,8 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, static void cpuset_change_task_nodemask(struct task_struct *tsk, nodemask_t *newmems) { + bool need_loop; + repeat: /* * Allow tasks that have access to memory reserves because they have @@ -960,10 +975,17 @@ repeat: return; task_lock(tsk); + /* + * Determine if a loop is necessary if another thread is doing + * get_mems_allowed(). If at least one node remains unchanged and + * tsk does not have a mempolicy, then an empty nodemask will not be + * possible when mems_allowed is larger than a word. + */ + need_loop = task_has_mempolicy(tsk) || + !nodes_intersects(*newmems, tsk->mems_allowed); nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1); - /* * ensure checking ->mems_allowed_change_disable after setting all new * allowed nodes. @@ -982,7 +1004,7 @@ repeat: * Allocation of memory is very fast, we needn't sleep when waiting * for the read-side. */ - while (ACCESS_ONCE(tsk->mems_allowed_change_disable)) { + while (need_loop && ACCESS_ONCE(tsk->mems_allowed_change_disable)) { task_unlock(tsk); if (!task_curr(tsk)) yield(); |