diff options
| -rw-r--r-- | kernel/cgroup/cpuset.c | 29 |
1 files changed, 8 insertions, 21 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 5fd1bdbaa381..ca8376e5008c 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1038,38 +1038,25 @@ static void cpuset_post_attach(void) * @tsk: the task to change * @newmems: new nodes that the task will be set * - * In order to avoid seeing no nodes if the old and new nodes are disjoint, - * we structure updates as setting all new allowed nodes, then clearing newly - * disallowed ones. + * We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed + * and rebind an eventual tasks' mempolicy. If the task is allocating in + * parallel, it might temporarily see an empty intersection, which results in + * a seqlock check and retry before OOM or allocation failure. */ static void cpuset_change_task_nodemask(struct task_struct *tsk, nodemask_t *newmems) { - bool need_loop; - task_lock(tsk); - /* - * Determine if a loop is necessary if another thread is doing - * read_mems_allowed_begin(). 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); - if (need_loop) { - local_irq_disable(); - write_seqcount_begin(&tsk->mems_allowed_seq); - } + local_irq_disable(); + write_seqcount_begin(&tsk->mems_allowed_seq); nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); mpol_rebind_task(tsk, newmems); tsk->mems_allowed = *newmems; - if (need_loop) { - write_seqcount_end(&tsk->mems_allowed_seq); - local_irq_enable(); - } + write_seqcount_end(&tsk->mems_allowed_seq); + local_irq_enable(); task_unlock(tsk); } |