From: chaixianping <[email protected]> Fix the race between fork and update_cpumask or update_nodemask. Scenario as follows: 1)A process fork a child process, the child process have inherited the parent process cpus_allowed,mems_allowed Before being added cset->tasks list. 2)Update_cpumask or update_nodemask change the parent's allowed to a new value, *but the child still is the old value. after being added cset->tasks list.
Signed-off-by: Xianping Chai <[email protected]> Signed-off-by: Zhenghua Jia <[email protected]> Signed-off-by: Leeyou <[email protected]> Signed-off-by: Lei Liu <[email protected]> --- kernel/cpuset.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index c7fd277..090b700 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1015,6 +1015,33 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, } } + +/* + *Fix the race between fork and update_cpumask or update_nodemask. + *Scenario as follows: + *1)A process fork a child process, the child process have + *inherited the parent process cpus_allowed,mems_allowed + *Before being added cset->tasks list. + *2)Update_cpumask or update_nodemask change the parent's allowed + *to a new value, *but the child still is the old value + *after being added cset->tasks list. + */ +static void cpuset_fork(struct task_struct *task) +{ + nodemask_t cpuset_mems_allowed; + + mutex_lock(&cpuset_mutex); + rcu_read_lock(); + + do_set_cpus_allowed(task, task_cs(task)->effective_cpus); + + guarantee_online_mems(task_cs(task), &cpuset_mems_allowed); + task->mems_allowed = cpuset_mems_allowed; + + rcu_read_unlock(); + mutex_unlock(&cpuset_mutex); +} + static void cpuset_post_attach(void) { flush_workqueue(cpuset_migrate_mm_wq); @@ -2078,6 +2105,7 @@ struct cgroup_subsys cpuset_cgrp_subsys = { .cancel_attach = cpuset_cancel_attach, .attach = cpuset_attach, .post_attach = cpuset_post_attach, + .fork = cpuset_fork, .bind = cpuset_bind, .legacy_cftypes = files, .early_init = true, -- 2.6.2
