Re: [PATCH v8 2/3] cgroups: add per-thread subsystem callbacks

From: Paul Menage
Date: Thu Mar 03 2011 - 13:00:38 EST


On Mon, Feb 7, 2011 at 5:39 PM, Ben Blum <bblum@xxxxxxxxxxxxxx> wrote:
> Add cgroup subsystem callbacks for per-thread attachment
>
> From: Ben Blum <bblum@xxxxxxxxxxxxxx>
>
> This patch adds can_attach_task, pre_attach, and attach_task as new callbacks
> for cgroups's subsystem interface. Unlike can_attach and attach, these are for
> per-thread operations, to be called potentially many times when attaching an
> entire threadgroup.
>
> Also, the old "bool threadgroup" interface is removed, as replaced by this.
> All subsystems are modified for the new interface - of note is cpuset, which
> requires from/to nodemasks for attach to be globally scoped (though per-cpuset
> would work too) to persist from its pre_attach to attach_task and attach.
>
> This is a pre-patch for cgroup-procs-writable.patch.
>
> Signed-off-by: Ben Blum <bblum@xxxxxxxxxxxxxx>

Reviewed-by: Paul Menage <menage@xxxxxxxxxx>

Paul

> ---
>  Documentation/cgroups/cgroups.txt |   30 ++++++++---
>  block/blk-cgroup.c                |   18 ++----
>  include/linux/cgroup.h            |   10 ++--
>  kernel/cgroup.c                   |   17 +++++-
>  kernel/cgroup_freezer.c           |   26 ++++-----
>  kernel/cpuset.c                   |  105 ++++++++++++++++---------------------
>  kernel/ns_cgroup.c                |   23 +++-----
>  kernel/sched.c                    |   38 +------------
>  mm/memcontrol.c                   |   18 ++----
>  security/device_cgroup.c          |    3 -
>  10 files changed, 122 insertions(+), 166 deletions(-)
>
> diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
> index 190018b..d3c9a24 100644
> --- a/Documentation/cgroups/cgroups.txt
> +++ b/Documentation/cgroups/cgroups.txt
> @@ -563,7 +563,7 @@ rmdir() will fail with it. From this behavior, pre_destroy() can be
>  called multiple times against a cgroup.
>
>  int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -              struct task_struct *task, bool threadgroup)
> +              struct task_struct *task)
>  (cgroup_mutex held by caller)
>
>  Called prior to moving a task into a cgroup; if the subsystem
> @@ -572,9 +572,14 @@ task is passed, then a successful result indicates that *any*
>  unspecified task can be moved into the cgroup. Note that this isn't
>  called on a fork. If this method returns 0 (success) then this should
>  remain valid while the caller holds cgroup_mutex and it is ensured that either
> -attach() or cancel_attach() will be called in future. If threadgroup is
> -true, then a successful result indicates that all threads in the given
> -thread's threadgroup can be moved together.
> +attach() or cancel_attach() will be called in future.
> +
> +int can_attach_task(struct cgroup *cgrp, struct task_struct *tsk);
> +(cgroup_mutex held by caller)
> +
> +As can_attach, but for operations that must be run once per task to be
> +attached (possibly many when using cgroup_attach_proc). Called after
> +can_attach.
>
>  void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
>               struct task_struct *task, bool threadgroup)
> @@ -586,15 +591,24 @@ function, so that the subsystem can implement a rollback. If not, not necessary.
>  This will be called only about subsystems whose can_attach() operation have
>  succeeded.
>
> +void pre_attach(struct cgroup *cgrp);
> +(cgroup_mutex held by caller)
> +
> +For any non-per-thread attachment work that needs to happen before
> +attach_task. Needed by cpuset.
> +
>  void attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -           struct cgroup *old_cgrp, struct task_struct *task,
> -           bool threadgroup)
> +           struct cgroup *old_cgrp, struct task_struct *task)
>  (cgroup_mutex held by caller)
>
>  Called after the task has been attached to the cgroup, to allow any
>  post-attachment activity that requires memory allocations or blocking.
> -If threadgroup is true, the subsystem should take care of all threads
> -in the specified thread's threadgroup. Currently does not support any
> +
> +void attach_task(struct cgroup *cgrp, struct task_struct *tsk);
> +(cgroup_mutex held by caller)
> +
> +As attach, but for operations that must be run once per task to be attached,
> +like can_attach_task. Called before attach. Currently does not support any
>  subsystem that might need the old_cgrp for every thread in the group.
>
>  void fork(struct cgroup_subsy *ss, struct task_struct *task)
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index b1febd0..45b3809 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -30,10 +30,8 @@ EXPORT_SYMBOL_GPL(blkio_root_cgroup);
>
>  static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
>                                                  struct cgroup *);
> -static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
> -                             struct task_struct *, bool);
> -static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
> -                          struct cgroup *, struct task_struct *, bool);
> +static int blkiocg_can_attach_task(struct cgroup *, struct task_struct *);
> +static void blkiocg_attach_task(struct cgroup *, struct task_struct *);
>  static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
>  static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
>
> @@ -46,8 +44,8 @@ static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
>  struct cgroup_subsys blkio_subsys = {
>        .name = "blkio",
>        .create = blkiocg_create,
> -       .can_attach = blkiocg_can_attach,
> -       .attach = blkiocg_attach,
> +       .can_attach_task = blkiocg_can_attach_task,
> +       .attach_task = blkiocg_attach_task,
>        .destroy = blkiocg_destroy,
>        .populate = blkiocg_populate,
>  #ifdef CONFIG_BLK_CGROUP
> @@ -1475,9 +1473,7 @@ done:
>  * of the main cic data structures.  For now we allow a task to change
>  * its cgroup only if it's the only owner of its ioc.
>  */
> -static int blkiocg_can_attach(struct cgroup_subsys *subsys,
> -                               struct cgroup *cgroup, struct task_struct *tsk,
> -                               bool threadgroup)
> +static int blkiocg_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>  {
>        struct io_context *ioc;
>        int ret = 0;
> @@ -1492,9 +1488,7 @@ static int blkiocg_can_attach(struct cgroup_subsys *subsys,
>        return ret;
>  }
>
> -static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
> -                               struct cgroup *prev, struct task_struct *tsk,
> -                               bool threadgroup)
> +static void blkiocg_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>  {
>        struct io_context *ioc;
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index ce104e3..35b69b4 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -467,12 +467,14 @@ struct cgroup_subsys {
>        int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
>        void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
>        int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -                         struct task_struct *tsk, bool threadgroup);
> +                         struct task_struct *tsk);
> +       int (*can_attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
>        void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -                         struct task_struct *tsk, bool threadgroup);
> +                             struct task_struct *tsk);
> +       void (*pre_attach)(struct cgroup *cgrp);
> +       void (*attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
>        void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -                       struct cgroup *old_cgrp, struct task_struct *tsk,
> -                       bool threadgroup);
> +                      struct cgroup *old_cgrp, struct task_struct *tsk);
>        void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
>        void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
>        int (*populate)(struct cgroup_subsys *ss,
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 66a416b..616f27a 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -1750,7 +1750,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>
>        for_each_subsys(root, ss) {
>                if (ss->can_attach) {
> -                       retval = ss->can_attach(ss, cgrp, tsk, false);
> +                       retval = ss->can_attach(ss, cgrp, tsk);
>                        if (retval) {
>                                /*
>                                 * Remember on which subsystem the can_attach()
> @@ -1762,6 +1762,13 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>                                goto out;
>                        }
>                }
> +               if (ss->can_attach_task) {
> +                       retval = ss->can_attach_task(cgrp, tsk);
> +                       if (retval) {
> +                               failed_ss = ss;
> +                               goto out;
> +                       }
> +               }
>        }
>
>        task_lock(tsk);
> @@ -1798,8 +1805,12 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>        write_unlock(&css_set_lock);
>
>        for_each_subsys(root, ss) {
> +               if (ss->pre_attach)
> +                       ss->pre_attach(cgrp);
> +               if (ss->attach_task)
> +                       ss->attach_task(cgrp, tsk);
>                if (ss->attach)
> -                       ss->attach(ss, cgrp, oldcgrp, tsk, false);
> +                       ss->attach(ss, cgrp, oldcgrp, tsk);
>        }
>        set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
>        synchronize_rcu();
> @@ -1822,7 +1833,7 @@ out:
>                                 */
>                                break;
>                        if (ss->cancel_attach)
> -                               ss->cancel_attach(ss, cgrp, tsk, false);
> +                               ss->cancel_attach(ss, cgrp, tsk);
>                }
>        }
>        return retval;
> diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
> index e7bebb7..e691818 100644
> --- a/kernel/cgroup_freezer.c
> +++ b/kernel/cgroup_freezer.c
> @@ -160,7 +160,7 @@ static void freezer_destroy(struct cgroup_subsys *ss,
>  */
>  static int freezer_can_attach(struct cgroup_subsys *ss,
>                              struct cgroup *new_cgroup,
> -                             struct task_struct *task, bool threadgroup)
> +                             struct task_struct *task)
>  {
>        struct freezer *freezer;
>
> @@ -172,26 +172,17 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
>        if (freezer->state != CGROUP_THAWED)
>                return -EBUSY;
>
> +       return 0;
> +}
> +
> +static int freezer_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +{
>        rcu_read_lock();
> -       if (__cgroup_freezing_or_frozen(task)) {
> +       if (__cgroup_freezing_or_frozen(tsk)) {
>                rcu_read_unlock();
>                return -EBUSY;
>        }
>        rcu_read_unlock();
> -
> -       if (threadgroup) {
> -               struct task_struct *c;
> -
> -               rcu_read_lock();
> -               list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
> -                       if (__cgroup_freezing_or_frozen(c)) {
> -                               rcu_read_unlock();
> -                               return -EBUSY;
> -                       }
> -               }
> -               rcu_read_unlock();
> -       }
> -
>        return 0;
>  }
>
> @@ -390,6 +381,9 @@ struct cgroup_subsys freezer_subsys = {
>        .populate       = freezer_populate,
>        .subsys_id      = freezer_subsys_id,
>        .can_attach     = freezer_can_attach,
> +       .can_attach_task = freezer_can_attach_task,
> +       .pre_attach     = NULL,
> +       .attach_task    = NULL,
>        .attach         = NULL,
>        .fork           = freezer_fork,
>        .exit           = NULL,
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index 4349935..5f71ca2 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -1372,14 +1372,10 @@ static int fmeter_getrate(struct fmeter *fmp)
>        return val;
>  }
>
> -/* Protected by cgroup_lock */
> -static cpumask_var_t cpus_attach;
> -
>  /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
>  static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
> -                            struct task_struct *tsk, bool threadgroup)
> +                            struct task_struct *tsk)
>  {
> -       int ret;
>        struct cpuset *cs = cgroup_cs(cont);
>
>        if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
> @@ -1396,29 +1392,42 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
>        if (tsk->flags & PF_THREAD_BOUND)
>                return -EINVAL;
>
> -       ret = security_task_setscheduler(tsk);
> -       if (ret)
> -               return ret;
> -       if (threadgroup) {
> -               struct task_struct *c;
> -
> -               rcu_read_lock();
> -               list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
> -                       ret = security_task_setscheduler(c);
> -                       if (ret) {
> -                               rcu_read_unlock();
> -                               return ret;
> -                       }
> -               }
> -               rcu_read_unlock();
> -       }
>        return 0;
>  }
>
> -static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to,
> -                              struct cpuset *cs)
> +static int cpuset_can_attach_task(struct cgroup *cgrp, struct task_struct *task)
> +{
> +       return security_task_setscheduler(task);
> +}
> +
> +/*
> + * Protected by cgroup_lock. The nodemasks must be stored globally because
> + * dynamically allocating them is not allowed in pre_attach, and they must
> + * persist among pre_attach, attach_task, and attach.
> + */
> +static cpumask_var_t cpus_attach;
> +static nodemask_t cpuset_attach_nodemask_from;
> +static nodemask_t cpuset_attach_nodemask_to;
> +
> +/* Set-up work for before attaching each task. */
> +static void cpuset_pre_attach(struct cgroup *cont)
> +{
> +       struct cpuset *cs = cgroup_cs(cont);
> +
> +       if (cs == &top_cpuset)
> +               cpumask_copy(cpus_attach, cpu_possible_mask);
> +       else
> +               guarantee_online_cpus(cs, cpus_attach);
> +
> +       guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
> +}
> +
> +/* Per-thread attachment work. */
> +static void cpuset_attach_task(struct cgroup *cont, struct task_struct *tsk)
>  {
>        int err;
> +       struct cpuset *cs = cgroup_cs(cont);
> +
>        /*
>         * can_attach beforehand should guarantee that this doesn't fail.
>         * TODO: have a better way to handle failure here
> @@ -1426,56 +1435,31 @@ static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to,
>        err = set_cpus_allowed_ptr(tsk, cpus_attach);
>        WARN_ON_ONCE(err);
>
> -       cpuset_change_task_nodemask(tsk, to);
> +       cpuset_change_task_nodemask(tsk, &cpuset_attach_nodemask_to);
>        cpuset_update_task_spread_flag(cs, tsk);
> -
>  }
>
>  static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
> -                         struct cgroup *oldcont, struct task_struct *tsk,
> -                         bool threadgroup)
> +                         struct cgroup *oldcont, struct task_struct *tsk)
>  {
>        struct mm_struct *mm;
>        struct cpuset *cs = cgroup_cs(cont);
>        struct cpuset *oldcs = cgroup_cs(oldcont);
> -       NODEMASK_ALLOC(nodemask_t, from, GFP_KERNEL);
> -       NODEMASK_ALLOC(nodemask_t, to, GFP_KERNEL);
> -
> -       if (from == NULL || to == NULL)
> -               goto alloc_fail;
>
> -       if (cs == &top_cpuset) {
> -               cpumask_copy(cpus_attach, cpu_possible_mask);
> -       } else {
> -               guarantee_online_cpus(cs, cpus_attach);
> -       }
> -       guarantee_online_mems(cs, to);
> -
> -       /* do per-task migration stuff possibly for each in the threadgroup */
> -       cpuset_attach_task(tsk, to, cs);
> -       if (threadgroup) {
> -               struct task_struct *c;
> -               rcu_read_lock();
> -               list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
> -                       cpuset_attach_task(c, to, cs);
> -               }
> -               rcu_read_unlock();
> -       }
> -
> -       /* change mm; only needs to be done once even if threadgroup */
> -       *from = oldcs->mems_allowed;
> -       *to = cs->mems_allowed;
> +       /*
> +        * Change mm, possibly for multiple threads in a threadgroup. This is
> +        * expensive and may sleep.
> +        */
> +       cpuset_attach_nodemask_from = oldcs->mems_allowed;
> +       cpuset_attach_nodemask_to = cs->mems_allowed;
>        mm = get_task_mm(tsk);
>        if (mm) {
> -               mpol_rebind_mm(mm, to);
> +               mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
>                if (is_memory_migrate(cs))
> -                       cpuset_migrate_mm(mm, from, to);
> +                       cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from,
> +                                         &cpuset_attach_nodemask_to);
>                mmput(mm);
>        }
> -
> -alloc_fail:
> -       NODEMASK_FREE(from);
> -       NODEMASK_FREE(to);
>  }
>
>  /* The various types of files and directories in a cpuset file system */
> @@ -1928,6 +1912,9 @@ struct cgroup_subsys cpuset_subsys = {
>        .create = cpuset_create,
>        .destroy = cpuset_destroy,
>        .can_attach = cpuset_can_attach,
> +       .can_attach_task = cpuset_can_attach_task,
> +       .pre_attach = cpuset_pre_attach,
> +       .attach_task = cpuset_attach_task,
>        .attach = cpuset_attach,
>        .populate = cpuset_populate,
>        .post_clone = cpuset_post_clone,
> diff --git a/kernel/ns_cgroup.c b/kernel/ns_cgroup.c
> index 2c98ad9..1fc2b1b 100644
> --- a/kernel/ns_cgroup.c
> +++ b/kernel/ns_cgroup.c
> @@ -43,7 +43,7 @@ int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
>  *        ancestor cgroup thereof)
>  */
>  static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
> -                        struct task_struct *task, bool threadgroup)
> +                        struct task_struct *task)
>  {
>        if (current != task) {
>                if (!capable(CAP_SYS_ADMIN))
> @@ -53,21 +53,13 @@ static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
>                        return -EPERM;
>        }
>
> -       if (!cgroup_is_descendant(new_cgroup, task))
> -               return -EPERM;
> -
> -       if (threadgroup) {
> -               struct task_struct *c;
> -               rcu_read_lock();
> -               list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
> -                       if (!cgroup_is_descendant(new_cgroup, c)) {
> -                               rcu_read_unlock();
> -                               return -EPERM;
> -                       }
> -               }
> -               rcu_read_unlock();
> -       }
> +       return 0;
> +}
>
> +static int ns_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +{
> +       if (!cgroup_is_descendant(cgrp, tsk))
> +               return -EPERM;
>        return 0;
>  }
>
> @@ -112,6 +104,7 @@ static void ns_destroy(struct cgroup_subsys *ss,
>  struct cgroup_subsys ns_subsys = {
>        .name = "ns",
>        .can_attach = ns_can_attach,
> +       .can_attach_task = ns_can_attach_task,
>        .create = ns_create,
>        .destroy  = ns_destroy,
>        .subsys_id = ns_subsys_id,
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 218ef20..d619f1d 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -8655,42 +8655,10 @@ cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>        return 0;
>  }
>
> -static int
> -cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -                     struct task_struct *tsk, bool threadgroup)
> -{
> -       int retval = cpu_cgroup_can_attach_task(cgrp, tsk);
> -       if (retval)
> -               return retval;
> -       if (threadgroup) {
> -               struct task_struct *c;
> -               rcu_read_lock();
> -               list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
> -                       retval = cpu_cgroup_can_attach_task(cgrp, c);
> -                       if (retval) {
> -                               rcu_read_unlock();
> -                               return retval;
> -                       }
> -               }
> -               rcu_read_unlock();
> -       }
> -       return 0;
> -}
> -
>  static void
> -cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
> -                 struct cgroup *old_cont, struct task_struct *tsk,
> -                 bool threadgroup)
> +cpu_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>  {
>        sched_move_task(tsk);
> -       if (threadgroup) {
> -               struct task_struct *c;
> -               rcu_read_lock();
> -               list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
> -                       sched_move_task(c);
> -               }
> -               rcu_read_unlock();
> -       }
>  }
>
>  #ifdef CONFIG_FAIR_GROUP_SCHED
> @@ -8763,8 +8731,8 @@ struct cgroup_subsys cpu_cgroup_subsys = {
>        .name           = "cpu",
>        .create         = cpu_cgroup_create,
>        .destroy        = cpu_cgroup_destroy,
> -       .can_attach     = cpu_cgroup_can_attach,
> -       .attach         = cpu_cgroup_attach,
> +       .can_attach_task = cpu_cgroup_can_attach_task,
> +       .attach_task    = cpu_cgroup_attach_task,
>        .populate       = cpu_cgroup_populate,
>        .subsys_id      = cpu_cgroup_subsys_id,
>        .early_init     = 1,
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 729beb7..995f0b9 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4720,8 +4720,7 @@ static void mem_cgroup_clear_mc(void)
>
>  static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
>                                struct cgroup *cgroup,
> -                               struct task_struct *p,
> -                               bool threadgroup)
> +                               struct task_struct *p)
>  {
>        int ret = 0;
>        struct mem_cgroup *mem = mem_cgroup_from_cont(cgroup);
> @@ -4775,8 +4774,7 @@ static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
>
>  static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
>                                struct cgroup *cgroup,
> -                               struct task_struct *p,
> -                               bool threadgroup)
> +                               struct task_struct *p)
>  {
>        mem_cgroup_clear_mc();
>  }
> @@ -4880,8 +4878,7 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
>  static void mem_cgroup_move_task(struct cgroup_subsys *ss,
>                                struct cgroup *cont,
>                                struct cgroup *old_cont,
> -                               struct task_struct *p,
> -                               bool threadgroup)
> +                               struct task_struct *p)
>  {
>        if (!mc.mm)
>                /* no need to move charge */
> @@ -4893,22 +4890,19 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
>  #else  /* !CONFIG_MMU */
>  static int mem_cgroup_can_attach(struct cgroup_subsys *ss,
>                                struct cgroup *cgroup,
> -                               struct task_struct *p,
> -                               bool threadgroup)
> +                               struct task_struct *p)
>  {
>        return 0;
>  }
>  static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss,
>                                struct cgroup *cgroup,
> -                               struct task_struct *p,
> -                               bool threadgroup)
> +                               struct task_struct *p)
>  {
>  }
>  static void mem_cgroup_move_task(struct cgroup_subsys *ss,
>                                struct cgroup *cont,
>                                struct cgroup *old_cont,
> -                               struct task_struct *p,
> -                               bool threadgroup)
> +                               struct task_struct *p)
>  {
>  }
>  #endif
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 8d9c48f..cd1f779 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -62,8 +62,7 @@ static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
>  struct cgroup_subsys devices_subsys;
>
>  static int devcgroup_can_attach(struct cgroup_subsys *ss,
> -               struct cgroup *new_cgroup, struct task_struct *task,
> -               bool threadgroup)
> +               struct cgroup *new_cgroup, struct task_struct *task)
>  {
>        if (current != task && !capable(CAP_SYS_ADMIN))
>                        return -EPERM;
>
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