diff options
| -rw-r--r-- | include/linux/cgroup.h | 21 | ||||
| -rw-r--r-- | include/linux/sched.h | 4 | ||||
| -rw-r--r-- | kernel/cgroup.c | 9 | ||||
| -rw-r--r-- | kernel/kthread.c | 3 |
4 files changed, 33 insertions, 4 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index cb91b44f5f78..ad2bcf647b9a 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -528,6 +528,25 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp) pr_cont_kernfs_path(cgrp->kn); } +static inline void cgroup_init_kthreadd(void) +{ + /* + * kthreadd is inherited by all kthreads, keep it in the root so + * that the new kthreads are guaranteed to stay in the root until + * initialization is finished. + */ + current->no_cgroup_migration = 1; +} + +static inline void cgroup_kthread_ready(void) +{ + /* + * This kthread finished initialization. The creator should have + * set PF_NO_SETAFFINITY if this kthread should stay in the root. + */ + current->no_cgroup_migration = 0; +} + #else /* !CONFIG_CGROUPS */ struct cgroup_subsys_state; @@ -551,6 +570,8 @@ static inline void cgroup_free(struct task_struct *p) {} static inline int cgroup_init_early(void) { return 0; } static inline int cgroup_init(void) { return 0; } +static inline void cgroup_init_kthreadd(void) {} +static inline void cgroup_kthread_ready(void) {} #endif /* !CONFIG_CGROUPS */ diff --git a/include/linux/sched.h b/include/linux/sched.h index ce0f61dcd887..352213b360d7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1475,6 +1475,10 @@ struct task_struct { #ifdef CONFIG_COMPAT_BRK unsigned brk_randomized:1; #endif +#ifdef CONFIG_CGROUPS + /* disallow userland-initiated cgroup migration */ + unsigned no_cgroup_migration:1; +#endif unsigned long atomic_flags; /* Flags needing atomic access. */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 127c63e02d52..4cb94b678e9f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2752,11 +2752,12 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, tsk = tsk->group_leader; /* - * Workqueue threads may acquire PF_NO_SETAFFINITY and become - * trapped in a cpuset, or RT worker may be born in a cgroup - * with no rt_runtime allocated. Just say no. + * kthreads may acquire PF_NO_SETAFFINITY during initialization. + * If userland migrates such a kthread to a non-root cgroup, it can + * become trapped in a cpuset, or RT kthread may be born in a + * cgroup with no rt_runtime allocated. Just say no. */ - if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { + if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) { ret = -EINVAL; goto out_unlock_rcu; } diff --git a/kernel/kthread.c b/kernel/kthread.c index 9ff173dca1ae..850b255649a2 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -18,6 +18,7 @@ #include <linux/freezer.h> #include <linux/ptrace.h> #include <linux/uaccess.h> +#include <linux/cgroup.h> #include <trace/events/sched.h> static DEFINE_SPINLOCK(kthread_create_lock); @@ -205,6 +206,7 @@ static int kthread(void *_create) ret = -EINTR; if (!test_bit(KTHREAD_SHOULD_STOP, &self.flags)) { + cgroup_kthread_ready(); __kthread_parkme(&self); ret = threadfn(data); } @@ -510,6 +512,7 @@ int kthreadd(void *unused) set_mems_allowed(node_states[N_MEMORY]); current->flags |= PF_NOFREEZE; + cgroup_init_kthreadd(); for (;;) { set_current_state(TASK_INTERRUPTIBLE); |