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Merge branch 'for-4.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:
 "Two fixes for cgroup.

   - There still was a hole in enforcing cpuset rules, fixed by Li.

   - The recent switch to global percpu_rwseom for threadgroup locking
     revealed a couple issues in how percpu_rwsem is implemented and
     used by cgroup.  Balbir found that the read locking section was too
     wide unnecessarily including operations which can often depend on
     IOs.  With percpu_rwsem updates (coming through a different tree)
     and reduction of read locking section, all the reported locking
     latency issues, including the android one, are resolved.

  It looks like we can keep global percpu_rwsem locking for now.  If
  there actually are cases which can't be resolved, we can go back to
  more complex per-signal_struct locking"

* 'for-4.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: reduce read locked section of cgroup_threadgroup_rwsem during fork
  cpuset: make sure new tasks conform to the current config of the cpuset
This commit is contained in:
Linus Torvalds 2016-08-30 09:31:59 -07:00
parent e4e98c460a 568ac88821
commit 748e7fc209
2 changed files with 17 additions and 2 deletions
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15
kernel/cpuset.c
View File

@ -2069,6 +2069,20 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
mutex_unlock(&cpuset_mutex);
}
/*
* Make sure the new task conform to the current state of its parent,
* which could have been changed by cpuset just after it inherits the
* state from the parent and before it sits on the cgroup's task list.
*/
void cpuset_fork(struct task_struct *task)
{
if (task_css_is_root(task, cpuset_cgrp_id))
return;
set_cpus_allowed_ptr(task, &current->cpus_allowed);
task->mems_allowed = current->mems_allowed;
}
struct cgroup_subsys cpuset_cgrp_subsys = {
.css_alloc = cpuset_css_alloc,
.css_online = cpuset_css_online,
@ -2079,6 +2093,7 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
.attach = cpuset_attach,
.post_attach = cpuset_post_attach,
.bind = cpuset_bind,
.fork = cpuset_fork,
.legacy_cftypes = files,
.early_init = true,
};

4
kernel/fork.c
View File

@ -1404,7 +1404,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->real_start_time = ktime_get_boot_ns();
p->io_context = NULL;
p->audit_context = NULL;
threadgroup_change_begin(current);
cgroup_fork(p);
#ifdef CONFIG_NUMA
p->mempolicy = mpol_dup(p->mempolicy);
@ -1556,6 +1555,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
INIT_LIST_HEAD(&p->thread_group);
p->task_works = NULL;
threadgroup_change_begin(current);
/*
* Ensure that the cgroup subsystem policies allow the new process to be
* forked. It should be noted the the new process's css_set can be changed
@ -1656,6 +1656,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
bad_fork_cancel_cgroup:
cgroup_cancel_fork(p);
bad_fork_free_pid:
threadgroup_change_end(current);
if (pid != &init_struct_pid)
free_pid(pid);
bad_fork_cleanup_thread:
@ -1688,7 +1689,6 @@ bad_fork_cleanup_policy:
mpol_put(p->mempolicy);
bad_fork_cleanup_threadgroup_lock:
#endif
threadgroup_change_end(current);
delayacct_tsk_free(p);
bad_fork_cleanup_count:
atomic_dec(&p->cred->user->processes);