diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index d99218a1e043..c0efd80ba40f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1949,6 +1949,32 @@ static inline int tsk_nr_cpus_allowed(struct task_struct *p) #define TNF_FAULT_LOCAL 0x08 #define TNF_MIGRATE_FAIL 0x10 +static inline bool in_vfork(struct task_struct *tsk) +{ + bool ret; + + /* + * need RCU to access ->real_parent if CLONE_VM was used along with + * CLONE_PARENT. + * + * We check real_parent->mm == tsk->mm because CLONE_VFORK does not + * imply CLONE_VM + * + * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus + * ->real_parent is not necessarily the task doing vfork(), so in + * theory we can't rely on task_lock() if we want to dereference it. + * + * And in this case we can't trust the real_parent->mm == tsk->mm + * check, it can be false negative. But we do not care, if init or + * another oom-unkillable task does this it should blame itself. + */ + rcu_read_lock(); + ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm; + rcu_read_unlock(); + + return ret; +} + #ifdef CONFIG_NUMA_BALANCING extern void task_numa_fault(int last_node, int node, int pages, int flags); extern pid_t task_numa_group_id(struct task_struct *p); |