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Merge branch 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

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Pull cgroup updates from Tejun Heo:
 "Nothing major. Two notable fixes are Li's second stab at fixing the
  long-standing race condition in the mount path and suppression of
  spurious warning from cgroup_get(). All other changes are trivial"

* 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: mark cgroup_get() with __maybe_unused
  cgroup: avoid attaching a cgroup root to two different superblocks, take 2
  cgroup: fix spurious warnings on cgroup_is_dead() from cgroup_sk_alloc()
  cgroup: move cgroup_subsys_state parent field for cache locality
  cpuset: Remove cpuset_update_active_cpus()'s parameter.
  cgroup: switch to BUG_ON()
  cgroup: drop duplicate header nsproxy.h
  kernel: convert css_set.refcount from atomic_t to refcount_t
  kernel: convert cgroup_namespace.count from atomic_t to refcount_t
This commit is contained in:
Linus Torvalds
2017-05-01 13:52:24 -07:00
parent ad1490bcd2 310b4816a5
commit 9410091dd5
9 changed files with 67 additions and 41 deletions
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20
kernel/cgroup/cgroup-v1.c
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@@ -346,7 +346,7 @@ static int cgroup_task_count(const struct cgroup *cgrp)
spin_lock_irq(&css_set_lock);
list_for_each_entry(link, &cgrp->cset_links, cset_link)
count += atomic_read(&link->cset->refcount);
count += refcount_read(&link->cset->refcount);
spin_unlock_irq(&css_set_lock);
return count;
}
@@ -1072,6 +1072,7 @@ struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
struct cgroup_subsys *ss;
struct dentry *dentry;
int i, ret;
bool new_root = false;
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
@@ -1181,10 +1182,11 @@ struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
ret = -ENOMEM;
goto out_unlock;
}
new_root = true;
init_cgroup_root(root, &opts);
ret = cgroup_setup_root(root, opts.subsys_mask);
ret = cgroup_setup_root(root, opts.subsys_mask, PERCPU_REF_INIT_DEAD);
if (ret)
cgroup_free_root(root);
@@ -1200,6 +1202,18 @@ out_free:
dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
CGROUP_SUPER_MAGIC, ns);
/*
* There's a race window after we release cgroup_mutex and before
* allocating a superblock. Make sure a concurrent process won't
* be able to re-use the root during this window by delaying the
* initialization of root refcnt.
*/
if (new_root) {
mutex_lock(&cgroup_mutex);
percpu_ref_reinit(&root->cgrp.self.refcnt);
mutex_unlock(&cgroup_mutex);
}
/*
* If @pinned_sb, we're reusing an existing root and holding an
* extra ref on its sb. Mount is complete. Put the extra ref.
@@ -1286,7 +1300,7 @@ static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
u64 count;
rcu_read_lock();
count = atomic_read(&task_css_set(current)->refcount);
count = refcount_read(&task_css_set(current)->refcount);
rcu_read_unlock();
return count;
}