10 files changed, 200 insertions, 198 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 641e56494a92..da0dae0600e6 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -638,8 +638,10 @@ struct cgroup_subsys {
         struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
         int (*css_online)(struct cgroup_subsys_state *css);
         void (*css_offline)(struct cgroup_subsys_state *css);
+        void (*css_released)(struct cgroup_subsys_state *css);
         void (*css_free)(struct cgroup_subsys_state *css);
         void (*css_reset)(struct cgroup_subsys_state *css);
+        void (*css_e_css_changed)(struct cgroup_subsys_state *css);
 
         int (*can_attach)(struct cgroup_subsys_state *css,
                           struct cgroup_taskset *tset);
@@ -934,6 +936,8 @@ void css_task_iter_end(struct css_task_iter *it);
 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
 
+struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
+                                             struct cgroup_subsys *ss);
 struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
                                                        struct cgroup_subsys *ss);
 
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 2f073db7392e..1b357997cac5 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -48,29 +48,16 @@ extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
 void cpuset_init_current_mems_allowed(void);
 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask);
 
-extern int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask);
-extern int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask);
+extern int __cpuset_node_allowed(int node, gfp_t gfp_mask);
 
-static inline int cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
+static inline int cpuset_node_allowed(int node, gfp_t gfp_mask)
 {
-        return nr_cpusets() <= 1 ||
-                __cpuset_node_allowed_softwall(node, gfp_mask);
+        return nr_cpusets() <= 1 || __cpuset_node_allowed(node, gfp_mask);
 }
 
-static inline int cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
+static inline int cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 {
-        return nr_cpusets() <= 1 ||
-                __cpuset_node_allowed_hardwall(node, gfp_mask);
-}
-
-static inline int cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
-{
-        return cpuset_node_allowed_softwall(zone_to_nid(z), gfp_mask);
-}
-
-static inline int cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
-{
-        return cpuset_node_allowed_hardwall(zone_to_nid(z), gfp_mask);
+        return cpuset_node_allowed(zone_to_nid(z), gfp_mask);
 }
 
 extern int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
@@ -179,22 +166,12 @@ static inline int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
         return 1;
 }
 
-static inline int cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
-{
-        return 1;
-}
-
-static inline int cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
-{
-        return 1;
-}
-
-static inline int cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
+static inline int cpuset_node_allowed(int node, gfp_t gfp_mask)
 {
         return 1;
 }
 
-static inline int cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
+static inline int cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 {
         return 1;
 }
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 136eceadeed1..bb263d0caab3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -277,6 +277,10 @@ static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
         if (!(cgrp->root->subsys_mask & (1 << ss->id)))
                 return NULL;
 
+        /*
+         * This function is used while updating css associations and thus
+         * can't test the csses directly.  Use ->child_subsys_mask.
+         */
         while (cgroup_parent(cgrp) &&
                !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id)))
                 cgrp = cgroup_parent(cgrp);
@@ -284,6 +288,39 @@ static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
         return cgroup_css(cgrp, ss);
 }
 
+/**
+ * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest
+ *
+ * Find and get the effective css of @cgrp for @ss.  The effective css is
+ * defined as the matching css of the nearest ancestor including self which
+ * has @ss enabled.  If @ss is not mounted on the hierarchy @cgrp is on,
+ * the root css is returned, so this function always returns a valid css.
+ * The returned css must be put using css_put().
+ */
+struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
+                                             struct cgroup_subsys *ss)
+{
+        struct cgroup_subsys_state *css;
+
+        rcu_read_lock();
+
+        do {
+                css = cgroup_css(cgrp, ss);
+
+                if (css && css_tryget_online(css))
+                        goto out_unlock;
+                cgrp = cgroup_parent(cgrp);
+        } while (cgrp);
+
+        css = init_css_set.subsys[ss->id];
+        css_get(css);
+out_unlock:
+        rcu_read_unlock();
+        return css;
+}
+
 /* convenient tests for these bits */
 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 {
@@ -1019,31 +1056,30 @@ static void cgroup_put(struct cgroup *cgrp)
 }
 
 /**
- * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * cgroup_calc_child_subsys_mask - calculate child_subsys_mask
  * @cgrp: the target cgroup
+ * @subtree_control: the new subtree_control mask to consider
  *
  * On the default hierarchy, a subsystem may request other subsystems to be
  * enabled together through its ->depends_on mask.  In such cases, more
  * subsystems than specified in "cgroup.subtree_control" may be enabled.
  *
- * This function determines which subsystems need to be enabled given the
- * current @cgrp->subtree_control and records it in
- * @cgrp->child_subsys_mask.  The resulting mask is always a superset of
- * @cgrp->subtree_control and follows the usual hierarchy rules.
+ * This function calculates which subsystems need to be enabled if
+ * @subtree_control is to be applied to @cgrp.  The returned mask is always
+ * a superset of @subtree_control and follows the usual hierarchy rules.
  */
-static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+static unsigned int cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
+                                                  unsigned int subtree_control)
 {
         struct cgroup *parent = cgroup_parent(cgrp);
-        unsigned int cur_ss_mask = cgrp->subtree_control;
+        unsigned int cur_ss_mask = subtree_control;
         struct cgroup_subsys *ss;
         int ssid;
 
         lockdep_assert_held(&cgroup_mutex);
 
-        if (!cgroup_on_dfl(cgrp)) {
-                cgrp->child_subsys_mask = cur_ss_mask;
-                return;
-        }
+        if (!cgroup_on_dfl(cgrp))
+                return cur_ss_mask;
 
         while (true) {
                 unsigned int new_ss_mask = cur_ss_mask;
@@ -1067,7 +1103,20 @@ static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
                 cur_ss_mask = new_ss_mask;
         }
 
-        cgrp->child_subsys_mask = cur_ss_mask;
+        return cur_ss_mask;
+}
+
+/**
+ * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * @cgrp: the target cgroup
+ *
+ * Update @cgrp->child_subsys_mask according to the current
+ * @cgrp->subtree_control using cgroup_calc_child_subsys_mask().
+ */
+static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+{
+        cgrp->child_subsys_mask =
+                cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control);
 }
 
 /**
@@ -2641,7 +2690,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
                                             loff_t off)
 {
         unsigned int enable = 0, disable = 0;
-        unsigned int css_enable, css_disable, old_ctrl, new_ctrl;
+        unsigned int css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
         struct cgroup *cgrp, *child;
         struct cgroup_subsys *ss;
         char *tok;
@@ -2693,36 +2742,6 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
                                 ret = -ENOENT;
                                 goto out_unlock;
                         }
-
-                        /*
-                         * @ss is already enabled through dependency and
-                         * we'll just make it visible.  Skip draining.
-                         */
-                        if (cgrp->child_subsys_mask & (1 << ssid))
-                                continue;
-
-                        /*
-                         * Because css offlining is asynchronous, userland
-                         * might try to re-enable the same controller while
-                         * the previous instance is still around.  In such
-                         * cases, wait till it's gone using offline_waitq.
-                         */
-                        cgroup_for_each_live_child(child, cgrp) {
-                                DEFINE_WAIT(wait);
-
-                                if (!cgroup_css(child, ss))
-                                        continue;
-
-                                cgroup_get(child);
-                                prepare_to_wait(&child->offline_waitq, &wait,
-                                                TASK_UNINTERRUPTIBLE);
-                                cgroup_kn_unlock(of->kn);
-                                schedule();
-                                finish_wait(&child->offline_waitq, &wait);
-                                cgroup_put(child);
-
-                                return restart_syscall();
-                        }
                 } else if (disable & (1 << ssid)) {
                         if (!(cgrp->subtree_control & (1 << ssid))) {
                                 disable &= ~(1 << ssid);
@@ -2758,19 +2777,48 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
          * subsystems than specified may need to be enabled or disabled
          * depending on subsystem dependencies.
          */
-        cgrp->subtree_control |= enable;
-        cgrp->subtree_control &= ~disable;
+        old_sc = cgrp->subtree_control;
+        old_ss = cgrp->child_subsys_mask;
+        new_sc = (old_sc | enable) & ~disable;
+        new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc);
 
-        old_ctrl = cgrp->child_subsys_mask;
-        cgroup_refresh_child_subsys_mask(cgrp);
-        new_ctrl = cgrp->child_subsys_mask;
-
-        css_enable = ~old_ctrl & new_ctrl;
-        css_disable = old_ctrl & ~new_ctrl;
+        css_enable = ~old_ss & new_ss;
+        css_disable = old_ss & ~new_ss;
         enable |= css_enable;
         disable |= css_disable;
 
         /*
+         * Because css offlining is asynchronous, userland might try to
+         * re-enable the same controller while the previous instance is
+         * still around.  In such cases, wait till it's gone using
+         * offline_waitq.
+         */
+        for_each_subsys(ss, ssid) {
+                if (!(css_enable & (1 << ssid)))
+                        continue;
+
+                cgroup_for_each_live_child(child, cgrp) {
+                        DEFINE_WAIT(wait);
+
+                        if (!cgroup_css(child, ss))
+                                continue;
+
+                        cgroup_get(child);
+                        prepare_to_wait(&child->offline_waitq, &wait,
+                                        TASK_UNINTERRUPTIBLE);
+                        cgroup_kn_unlock(of->kn);
+                        schedule();
+                        finish_wait(&child->offline_waitq, &wait);
+                        cgroup_put(child);
+
+                        return restart_syscall();
+                }
+        }
+
+        cgrp->subtree_control = new_sc;
+        cgrp->child_subsys_mask = new_ss;
+
+        /*
          * Create new csses or make the existing ones visible.  A css is
          * created invisible if it's being implicitly enabled through
          * dependency.  An invisible css is made visible when the userland
@@ -2825,6 +2873,24 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
                 }
         }
 
+        /*
+         * The effective csses of all the descendants (excluding @cgrp) may
+         * have changed.  Subsystems can optionally subscribe to this event
+         * by implementing ->css_e_css_changed() which is invoked if any of
+         * the effective csses seen from the css's cgroup may have changed.
+         */
+        for_each_subsys(ss, ssid) {
+                struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss);
+                struct cgroup_subsys_state *css;
+
+                if (!ss->css_e_css_changed || !this_css)
+                        continue;
+
+                css_for_each_descendant_pre(css, this_css)
+                        if (css != this_css)
+                                ss->css_e_css_changed(css);
+        }
+
         kernfs_activate(cgrp->kn);
         ret = 0;
 out_unlock:
@@ -2832,9 +2898,8 @@ out_unlock:
         return ret ?: nbytes;
 
 err_undo_css:
-        cgrp->subtree_control &= ~enable;
-        cgrp->subtree_control |= disable;
-        cgroup_refresh_child_subsys_mask(cgrp);
+        cgrp->subtree_control = old_sc;
+        cgrp->child_subsys_mask = old_ss;
 
         for_each_subsys(ss, ssid) {
                 if (!(enable & (1 << ssid)))
@@ -4370,6 +4435,8 @@ static void css_release_work_fn(struct work_struct *work)
         if (ss) {
                 /* css release path */
                 cgroup_idr_remove(&ss->css_idr, css->id);
+                if (ss->css_released)
+                        ss->css_released(css);
         } else {
                 /* cgroup release path */
                 cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 723cfc9d0ad7..64b257f6bca2 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -248,34 +248,34 @@ static struct cpuset top_cpuset = {
                 if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
 
 /*
- * There are two global mutexes guarding cpuset structures - cpuset_mutex
- * and callback_mutex.  The latter may nest inside the former.  We also
- * require taking task_lock() when dereferencing a task's cpuset pointer.
- * See "The task_lock() exception", at the end of this comment.
+ * There are two global locks guarding cpuset structures - cpuset_mutex and
+ * callback_lock. We also require taking task_lock() when dereferencing a
+ * task's cpuset pointer. See "The task_lock() exception", at the end of this
+ * comment.
  *
- * A task must hold both mutexes to modify cpusets.  If a task holds
+ * A task must hold both locks to modify cpusets.  If a task holds
  * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
- * is the only task able to also acquire callback_mutex and be able to
+ * is the only task able to also acquire callback_lock and be able to
  * modify cpusets.  It can perform various checks on the cpuset structure
  * first, knowing nothing will change.  It can also allocate memory while
  * just holding cpuset_mutex.  While it is performing these checks, various
- * callback routines can briefly acquire callback_mutex to query cpusets.
- * Once it is ready to make the changes, it takes callback_mutex, blocking
+ * callback routines can briefly acquire callback_lock to query cpusets.
+ * Once it is ready to make the changes, it takes callback_lock, blocking
  * everyone else.
  *
  * Calls to the kernel memory allocator can not be made while holding
- * callback_mutex, as that would risk double tripping on callback_mutex
+ * callback_lock, as that would risk double tripping on callback_lock
  * from one of the callbacks into the cpuset code from within
  * __alloc_pages().
  *
- * If a task is only holding callback_mutex, then it has read-only
+ * If a task is only holding callback_lock, then it has read-only
  * access to cpusets.
  *
  * Now, the task_struct fields mems_allowed and mempolicy may be changed
  * by other task, we use alloc_lock in the task_struct fields to protect
  * them.
  *
- * The cpuset_common_file_read() handlers only hold callback_mutex across
+ * The cpuset_common_file_read() handlers only hold callback_lock across
  * small pieces of code, such as when reading out possibly multi-word
  * cpumasks and nodemasks.
  *
@@ -284,7 +284,7 @@ static struct cpuset top_cpuset = {
  */
 
 static DEFINE_MUTEX(cpuset_mutex);
-static DEFINE_MUTEX(callback_mutex);
+static DEFINE_SPINLOCK(callback_lock);
 
 /*
  * CPU / memory hotplug is handled asynchronously.
@@ -329,7 +329,7 @@ static struct file_system_type cpuset_fs_type = {
  * One way or another, we guarantee to return some non-empty subset
  * of cpu_online_mask.
  *
- * Call with callback_mutex held.
+ * Call with callback_lock or cpuset_mutex held.
  */
 static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
 {
@@ -347,7 +347,7 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
  * One way or another, we guarantee to return some non-empty subset
  * of node_states[N_MEMORY].
  *
- * Call with callback_mutex held.
+ * Call with callback_lock or cpuset_mutex held.
  */
 static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 {
@@ -359,7 +359,7 @@ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
 /*
  * update task's spread flag if cpuset's page/slab spread flag is set
  *
- * Called with callback_mutex/cpuset_mutex held
+ * Call with callback_lock or cpuset_mutex held.
  */
 static void cpuset_update_task_spread_flag(struct cpuset *cs,
                                         struct task_struct *tsk)
@@ -886,9 +886,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
                         continue;
                 rcu_read_unlock();
 
-                mutex_lock(&callback_mutex);
+                spin_lock_irq(&callback_lock);
                 cpumask_copy(cp->effective_cpus, new_cpus);
-                mutex_unlock(&callback_mutex);
+                spin_unlock_irq(&callback_lock);
 
                 WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
                         !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
@@ -953,9 +953,9 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
         if (retval < 0)
                 return retval;
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 
         /* use trialcs->cpus_allowed as a temp variable */
         update_cpumasks_hier(cs, trialcs->cpus_allowed);
@@ -1142,9 +1142,9 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
                         continue;
                 rcu_read_unlock();
 
-                mutex_lock(&callback_mutex);
+                spin_lock_irq(&callback_lock);
                 cp->effective_mems = *new_mems;
-                mutex_unlock(&callback_mutex);
+                spin_unlock_irq(&callback_lock);
 
                 WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
                         !nodes_equal(cp->mems_allowed, cp->effective_mems));
@@ -1165,7 +1165,7 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
  * mempolicies and if the cpuset is marked 'memory_migrate',
  * migrate the tasks pages to the new memory.
  *
- * Call with cpuset_mutex held.  May take callback_mutex during call.
+ * Call with cpuset_mutex held. May take callback_lock during call.
  * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
  * lock each such tasks mm->mmap_sem, scan its vma's and rebind
  * their mempolicies to the cpusets new mems_allowed.
@@ -1212,9 +1212,9 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
         if (retval < 0)
                 goto done;
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         cs->mems_allowed = trialcs->mems_allowed;
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 
         /* use trialcs->mems_allowed as a temp variable */
         update_nodemasks_hier(cs, &cs->mems_allowed);
@@ -1305,9 +1305,9 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
         spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
                         || (is_spread_page(cs) != is_spread_page(trialcs)));
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         cs->flags = trialcs->flags;
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 
         if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
                 rebuild_sched_domains_locked();
@@ -1714,7 +1714,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
         count = seq_get_buf(sf, &buf);
         s = buf;
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
 
         switch (type) {
         case FILE_CPULIST:
@@ -1741,7 +1741,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v)
                 seq_commit(sf, -1);
         }
 out_unlock:
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
         return ret;
 }
 
@@ -1958,12 +1958,12 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
 
         cpuset_inc();
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         if (cgroup_on_dfl(cs->css.cgroup)) {
                 cpumask_copy(cs->effective_cpus, parent->effective_cpus);
                 cs->effective_mems = parent->effective_mems;
         }
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 
         if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
                 goto out_unlock;
@@ -1990,10 +1990,10 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
         }
         rcu_read_unlock();
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         cs->mems_allowed = parent->mems_allowed;
         cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 out_unlock:
         mutex_unlock(&cpuset_mutex);
         return 0;
@@ -2032,7 +2032,7 @@ static void cpuset_css_free(struct cgroup_subsys_state *css)
 static void cpuset_bind(struct cgroup_subsys_state *root_css)
 {
         mutex_lock(&cpuset_mutex);
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
 
         if (cgroup_on_dfl(root_css->cgroup)) {
                 cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
@@ -2043,7 +2043,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
                 top_cpuset.mems_allowed = top_cpuset.effective_mems;
         }
 
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
         mutex_unlock(&cpuset_mutex);
 }
 
@@ -2128,12 +2128,12 @@ hotplug_update_tasks_legacy(struct cpuset *cs,
 {
         bool is_empty;
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         cpumask_copy(cs->cpus_allowed, new_cpus);
         cpumask_copy(cs->effective_cpus, new_cpus);
         cs->mems_allowed = *new_mems;
         cs->effective_mems = *new_mems;
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 
         /*
          * Don't call update_tasks_cpumask() if the cpuset becomes empty,
@@ -2170,10 +2170,10 @@ hotplug_update_tasks(struct cpuset *cs,
         if (nodes_empty(*new_mems))
                 *new_mems = parent_cs(cs)->effective_mems;
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irq(&callback_lock);
         cpumask_copy(cs->effective_cpus, new_cpus);
         cs->effective_mems = *new_mems;
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irq(&callback_lock);
 
         if (cpus_updated)
                 update_tasks_cpumask(cs);
@@ -2259,21 +2259,21 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
 
         /* synchronize cpus_allowed to cpu_active_mask */
         if (cpus_updated) {
-                mutex_lock(&callback_mutex);
+                spin_lock_irq(&callback_lock);
                 if (!on_dfl)
                         cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
                 cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
-                mutex_unlock(&callback_mutex);
+                spin_unlock_irq(&callback_lock);
                 /* we don't mess with cpumasks of tasks in top_cpuset */
         }
 
         /* synchronize mems_allowed to N_MEMORY */
         if (mems_updated) {
-                mutex_lock(&callback_mutex);
+                spin_lock_irq(&callback_lock);
                 if (!on_dfl)
                         top_cpuset.mems_allowed = new_mems;
                 top_cpuset.effective_mems = new_mems;
-                mutex_unlock(&callback_mutex);
+                spin_unlock_irq(&callback_lock);
                 update_tasks_nodemask(&top_cpuset);
         }
 
@@ -2366,11 +2366,13 @@ void __init cpuset_init_smp(void)
 
 void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
 {
-        mutex_lock(&callback_mutex);
+        unsigned long flags;
+
+        spin_lock_irqsave(&callback_lock, flags);
         rcu_read_lock();
         guarantee_online_cpus(task_cs(tsk), pmask);
         rcu_read_unlock();
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irqrestore(&callback_lock, flags);
 }
 
 void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
@@ -2416,12 +2418,13 @@ void cpuset_init_current_mems_allowed(void)
 nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
 {
         nodemask_t mask;
+        unsigned long flags;
 
-        mutex_lock(&callback_mutex);
+        spin_lock_irqsave(&callback_lock, flags);
         rcu_read_lock();
         guarantee_online_mems(task_cs(tsk), &mask);
         rcu_read_unlock();
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irqrestore(&callback_lock, flags);
 
         return mask;
 }
@@ -2440,7 +2443,7 @@ int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
 /*
  * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
  * mem_hardwall ancestor to the specified cpuset.  Call holding
- * callback_mutex.  If no ancestor is mem_exclusive or mem_hardwall
+ * callback_lock.  If no ancestor is mem_exclusive or mem_hardwall
  * (an unusual configuration), then returns the root cpuset.
  */
 static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
@@ -2451,7 +2454,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
 }
 
 /**
- * cpuset_node_allowed_softwall - Can we allocate on a memory node?
+ * cpuset_node_allowed - Can we allocate on a memory node?
  * @node: is this an allowed node?
  * @gfp_mask: memory allocation flags
  *
@@ -2463,13 +2466,6 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
  * flag, yes.
  * Otherwise, no.
  *
- * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
- * cpuset_node_allowed_hardwall().  Otherwise, cpuset_node_allowed_softwall()
- * might sleep, and might allow a node from an enclosing cpuset.
- *
- * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
- * cpusets, and never sleeps.
- *
  * The __GFP_THISNODE placement logic is really handled elsewhere,
  * by forcibly using a zonelist starting at a specified node, and by
  * (in get_page_from_freelist()) refusing to consider the zones for
@@ -2482,13 +2478,12 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
  * GFP_KERNEL allocations are not so marked, so can escape to the
  * nearest enclosing hardwalled ancestor cpuset.
  *
- * Scanning up parent cpusets requires callback_mutex.  The
+ * Scanning up parent cpusets requires callback_lock.  The
  * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
  * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
  * current tasks mems_allowed came up empty on the first pass over
  * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
- * cpuset are short of memory, might require taking the callback_mutex
- * mutex.
+ * cpuset are short of memory, might require taking the callback_lock.
  *
  * The first call here from mm/page_alloc:get_page_from_freelist()
  * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
@@ -2505,20 +2500,15 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
  *      TIF_MEMDIE   - any node ok
  *      GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
  *      GFP_USER     - only nodes in current tasks mems allowed ok.
- *
- * Rule:
- *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
- *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
- *    the code that might scan up ancestor cpusets and sleep.
  */
-int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
+int __cpuset_node_allowed(int node, gfp_t gfp_mask)
 {
         struct cpuset *cs;              /* current cpuset ancestors */
         int allowed;                    /* is allocation in zone z allowed? */
+        unsigned long flags;
 
         if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
                 return 1;
-        might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
         if (node_isset(node, current->mems_allowed))
                 return 1;
         /*
@@ -2534,55 +2524,17 @@ int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
                 return 1;
 
         /* Not hardwall and node outside mems_allowed: scan up cpusets */
-        mutex_lock(&callback_mutex);
+        spin_lock_irqsave(&callback_lock, flags);
 
         rcu_read_lock();
         cs = nearest_hardwall_ancestor(task_cs(current));
         allowed = node_isset(node, cs->mems_allowed);
         rcu_read_unlock();
 
-        mutex_unlock(&callback_mutex);
+        spin_unlock_irqrestore(&callback_lock, flags);
         return allowed;
 }
 
-/*
- * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
- * @node: is this an allowed node?
- * @gfp_mask: memory allocation flags
- *
- * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
- * set, yes, we can always allocate.  If node is in our task's mems_allowed,
- * yes.  If the task has been OOM killed and has access to memory reserves as
- * specified by the TIF_MEMDIE flag, yes.
- * Otherwise, no.
- *
- * The __GFP_THISNODE placement logic is really handled elsewhere,
- * by forcibly using a zonelist starting at a specified node, and by
- * (in get_page_from_freelist()) refusing to consider the zones for
- * any node on the zonelist except the first.  By the time any such
- * calls get to this routine, we should just shut up and say 'yes'.
- *
- * Unlike the cpuset_node_allowed_softwall() variant, above,
- * this variant requires that the node be in the current task's
- * mems_allowed or that we're in interrupt.  It does not scan up the
- * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
- * It never sleeps.
- */
-int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
-{
-        if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
-                return 1;
-        if (node_isset(node, current->mems_allowed))
-                return 1;
-        /*
-         * Allow tasks that have access to memory reserves because they have
-         * been OOM killed to get memory anywhere.
-         */
-        if (unlikely(test_thread_flag(TIF_MEMDIE)))
-                return 1;
-        return 0;
-}
-
 /**
  * cpuset_mem_spread_node() - On which node to begin search for a file page
  * cpuset_slab_spread_node() - On which node to begin search for a slab page
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 30cd96879152..919b86a2164d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -582,7 +582,7 @@ retry_cpuset:
 
         for_each_zone_zonelist_nodemask(zone, z, zonelist,
                                                 MAX_NR_ZONES - 1, nodemask) {
-                if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask(h))) {
+                if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
                         page = dequeue_huge_page_node(h, zone_to_nid(zone));
                         if (page) {
                                 if (avoid_reserve)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3b014d326151..864bba992735 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -233,7 +233,7 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
         /* Check this allocation failure is caused by cpuset's wall function */
         for_each_zone_zonelist_nodemask(zone, z, zonelist,
                         high_zoneidx, nodemask)
-                if (!cpuset_zone_allowed_softwall(zone, gfp_mask))
+                if (!cpuset_zone_allowed(zone, gfp_mask))
                         cpuset_limited = true;
 
         if (cpuset_limited) {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a7198c065999..df542feaac3b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1990,7 +1990,7 @@ zonelist_scan:
 
         /*
          * Scan zonelist, looking for a zone with enough free.
-         * See also __cpuset_node_allowed_softwall() comment in kernel/cpuset.c.
+         * See also __cpuset_node_allowed() comment in kernel/cpuset.c.
          */
         for_each_zone_zonelist_nodemask(zone, z, zonelist,
                                                 high_zoneidx, nodemask) {
@@ -2001,7 +2001,7 @@ zonelist_scan:
                                 continue;
                 if (cpusets_enabled() &&
                         (alloc_flags & ALLOC_CPUSET) &&
-                        !cpuset_zone_allowed_softwall(zone, gfp_mask))
+                        !cpuset_zone_allowed(zone, gfp_mask))
                                 continue;
                 /*
                  * Distribute pages in proportion to the individual
@@ -2529,7 +2529,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
                         alloc_flags |= ALLOC_HARDER;
                 /*
                  * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
-                 * comment for __cpuset_node_allowed_softwall().
+                 * comment for __cpuset_node_allowed().
                  */
                 alloc_flags &= ~ALLOC_CPUSET;
         } else if (unlikely(rt_task(current)) && !in_interrupt())
diff --git a/mm/slab.c b/mm/slab.c
index 79e15f0a2a6e..fee275b5b6b7 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3015,7 +3015,7 @@ retry:
         for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
                 nid = zone_to_nid(zone);
 
-                if (cpuset_zone_allowed_hardwall(zone, flags) &&
+                if (cpuset_zone_allowed(zone, flags | __GFP_HARDWALL) &&
                         get_node(cache, nid) &&
                         get_node(cache, nid)->free_objects) {
                                 obj = ____cache_alloc_node(cache,
diff --git a/mm/slub.c b/mm/slub.c
index 386bbed76e94..765c5884d03d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1665,7 +1665,8 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
 
                         n = get_node(s, zone_to_nid(zone));
 
-                        if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
+                        if (n && cpuset_zone_allowed(zone,
+                                                     flags | __GFP_HARDWALL) &&
                                         n->nr_partial > s->min_partial) {
                                 object = get_partial_node(s, n, c, flags);
                                 if (object) {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4636d9e822c1..a384339bf718 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2405,7 +2405,8 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
                  * to global LRU.
                  */
                 if (global_reclaim(sc)) {
-                        if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+                        if (!cpuset_zone_allowed(zone,
+                                                 GFP_KERNEL | __GFP_HARDWALL))
                                 continue;
 
                         lru_pages += zone_reclaimable_pages(zone);
@@ -3388,7 +3389,7 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
         if (!populated_zone(zone))
                 return;
 
-        if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+        if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL))
                 return;
         pgdat = zone->zone_pgdat;
         if (pgdat->kswapd_max_order < order) {