On 02/26/2016 02:10 PM, Vladimir Davydov wrote:
> On Thu, Feb 25, 2016 at 07:19:38PM +0300, Andrey Ryabinin wrote:
> ...
>> @@ -2673,7 +2676,10 @@ static struct mnt_namespace *create_mnt_ns(struct
>> vfsmount *m)
>> struct mount *mnt = real_mount(m);
>> mnt->mnt_ns = new_ns;
>> new_ns->root = mnt;
>> + down_write(&namespace_sem);
>> list_add(&mnt->mnt_list, &new_ns->list);
>> + list_add(&new_ns->mntns_list, &get_exec_env()->mntns_list);
>
> Do we really need to link such mnt_ns?
>
I think, it shouldn't hurt at least.
Do we have a reason to not link these namespaces?
>> + up_write(&namespace_sem);
>> } else {
>> mntput(m);
>> }
>> @@ -2954,6 +2960,7 @@ void put_mnt_ns(struct mnt_namespace *ns)
>> namespace_lock();
>> br_write_lock(&vfsmount_lock);
>> umount_tree(ns->root, 0);
>> + list_del(&ns->mntns_list);
>
> Why under br_write_lock? namespace_lock should be enough.
Whether this this under br_write_lock or not doesn't matter absolutely.
It equally could be placed under lock or out of it.
>> br_write_unlock(&vfsmount_lock);
>> namespace_unlock();
>> free_mnt_ns(ns);
> ...
>> @@ -80,6 +80,7 @@ struct ve_struct ve0 = {
>> .sched_lat_ve.cur = &ve0_lat_stats,
>> .init_cred = &init_cred,
>> .mnt_nr = 0,
>> + .mntns_list = LIST_HEAD_INIT(ve0.mntns_list),
>
> It is initialized in ve_create below. Why is it not enough?
>
create_mnt_ns() called too early, before ve_create().
>> };
>> EXPORT_SYMBOL(ve0);
>>
>> @@ -652,6 +653,7 @@ do_init:
>> INIT_LIST_HEAD(&ve->devices);
>> INIT_LIST_HEAD(&ve->ve_list);
>> INIT_LIST_HEAD(&ve->devmnt_list);
>> + INIT_LIST_HEAD(&ve->mntns_list);
>> mutex_init(&ve->devmnt_mutex);
>> kmapset_init_key(&ve->ve_sysfs_perms);
>>
>> @@ -706,6 +708,8 @@ static void ve_destroy(struct cgroup *cg)
>> kmapset_unlink(&ve->ve_sysfs_perms, &ve_sysfs_perms);
>> free_ve_devmnts(ve);
>>
>> + WARN_ON(!list_empty(&ve->mntns_list));
>> +
>> ve_log_destroy(ve);
>> #if IS_ENABLED(CONFIG_BINFMT_MISC)
>> kfree(ve->binfmt_misc);
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