From: Waiman Long longman@redhat.com
Commit b94f9ac79a7395c2d6171cc753cc27942df0be73 upstream.
Since commit 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem"), cpuset_mutex has been replaced by cpuset_rwsem which is a percpu rwsem. However, the comments in kernel/cgroup/cpuset.c still reference cpuset_mutex which are now incorrect.
Change all the references of cpuset_mutex to cpuset_rwsem.
Fixes: 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem") Signed-off-by: Waiman Long longman@redhat.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/cgroup/cpuset.c | 56 +++++++++++++++++++++++++------------------------ 1 file changed, 29 insertions(+), 27 deletions(-)
--- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -299,17 +299,19 @@ static struct cpuset top_cpuset = { if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
/* - * There are two global locks guarding cpuset structures - cpuset_mutex and + * There are two global locks guarding cpuset structures - cpuset_rwsem 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. + * comment. The cpuset code uses only cpuset_rwsem write lock. Other + * kernel subsystems can use cpuset_read_lock()/cpuset_read_unlock() to + * prevent change to cpuset structures. * * 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 + * cpuset_rwsem, it blocks others wanting that rwsem, ensuring that it * 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 + * just holding cpuset_rwsem. While it is performing these checks, various * 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. @@ -380,7 +382,7 @@ static inline bool is_in_v2_mode(void) * One way or another, we guarantee to return some non-empty subset * of cpu_online_mask. * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) { @@ -410,7 +412,7 @@ static void guarantee_online_cpus(struct * One way or another, we guarantee to return some non-empty subset * of node_states[N_MEMORY]. * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask) { @@ -422,7 +424,7 @@ static void guarantee_online_mems(struct /* * update task's spread flag if cpuset's page/slab spread flag is set * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void cpuset_update_task_spread_flag(struct cpuset *cs, struct task_struct *tsk) @@ -443,7 +445,7 @@ static void cpuset_update_task_spread_fl * * One cpuset is a subset of another if all its allowed CPUs and * Memory Nodes are a subset of the other, and its exclusive flags - * are only set if the other's are set. Call holding cpuset_mutex. + * are only set if the other's are set. Call holding cpuset_rwsem. */
static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) @@ -552,7 +554,7 @@ static inline void free_cpuset(struct cp * If we replaced the flag and mask values of the current cpuset * (cur) with those values in the trial cpuset (trial), would * our various subset and exclusive rules still be valid? Presumes - * cpuset_mutex held. + * cpuset_rwsem held. * * 'cur' is the address of an actual, in-use cpuset. Operations * such as list traversal that depend on the actual address of the @@ -675,7 +677,7 @@ static void update_domain_attr_tree(stru rcu_read_unlock(); }
-/* Must be called with cpuset_mutex held. */ +/* Must be called with cpuset_rwsem held. */ static inline int nr_cpusets(void) { /* jump label reference count + the top-level cpuset */ @@ -701,7 +703,7 @@ static inline int nr_cpusets(void) * domains when operating in the severe memory shortage situations * that could cause allocation failures below. * - * Must be called with cpuset_mutex held. + * Must be called with cpuset_rwsem held. * * The three key local variables below are: * cp - cpuset pointer, used (together with pos_css) to perform a @@ -980,7 +982,7 @@ partition_and_rebuild_sched_domains(int * 'cpus' is removed, then call this routine to rebuild the * scheduler's dynamic sched domains. * - * Call with cpuset_mutex held. Takes get_online_cpus(). + * Call with cpuset_rwsem held. Takes get_online_cpus(). */ static void rebuild_sched_domains_locked(void) { @@ -1053,7 +1055,7 @@ void rebuild_sched_domains(void) * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed * * Iterate through each task of @cs updating its cpus_allowed to the - * effective cpuset's. As this function is called with cpuset_mutex held, + * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ static void update_tasks_cpumask(struct cpuset *cs) @@ -1328,7 +1330,7 @@ static int update_parent_subparts_cpumas * * On legacy hierachy, effective_cpus will be the same with cpu_allowed. * - * Called with cpuset_mutex held + * Called with cpuset_rwsem held */ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) { @@ -1688,12 +1690,12 @@ static void *cpuset_being_rebound; * @cs: the cpuset in which each task's mems_allowed mask needs to be changed * * Iterate through each task of @cs updating its mems_allowed to the - * effective cpuset's. As this function is called with cpuset_mutex held, + * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ static void update_tasks_nodemask(struct cpuset *cs) { - static nodemask_t newmems; /* protected by cpuset_mutex */ + static nodemask_t newmems; /* protected by cpuset_rwsem */ struct css_task_iter it; struct task_struct *task;
@@ -1706,7 +1708,7 @@ static void update_tasks_nodemask(struct * take while holding tasklist_lock. Forks can happen - the * mpol_dup() cpuset_being_rebound check will catch such forks, * and rebind their vma mempolicies too. Because we still hold - * the global cpuset_mutex, we know that no other rebind effort + * the global cpuset_rwsem, we know that no other rebind effort * will be contending for the global variable cpuset_being_rebound. * It's ok if we rebind the same mm twice; mpol_rebind_mm() * is idempotent. Also migrate pages in each mm to new nodes. @@ -1752,7 +1754,7 @@ static void update_tasks_nodemask(struct * * On legacy hiearchy, effective_mems will be the same with mems_allowed. * - * Called with cpuset_mutex held + * Called with cpuset_rwsem held */ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) { @@ -1805,7 +1807,7 @@ static void update_nodemasks_hier(struct * 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_lock during call. + * Call with cpuset_rwsem held. May take callback_lock during call. * Will take tasklist_lock, scan tasklist for tasks in cpuset cs, * lock each such tasks mm->mmap_lock, scan its vma's and rebind * their mempolicies to the cpusets new mems_allowed. @@ -1895,7 +1897,7 @@ static int update_relax_domain_level(str * @cs: the cpuset in which each task's spread flags needs to be changed * * Iterate through each task of @cs updating its spread flags. As this - * function is called with cpuset_mutex held, cpuset membership stays + * function is called with cpuset_rwsem held, cpuset membership stays * stable. */ static void update_tasks_flags(struct cpuset *cs) @@ -1915,7 +1917,7 @@ static void update_tasks_flags(struct cp * cs: the cpuset to update * turning_on: whether the flag is being set or cleared * - * Call with cpuset_mutex held. + * Call with cpuset_rwsem held. */
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, @@ -1964,7 +1966,7 @@ out: * cs: the cpuset to update * new_prs: new partition root state * - * Call with cpuset_mutex held. + * Call with cpuset_rwsem held. */ static int update_prstate(struct cpuset *cs, int new_prs) { @@ -2145,7 +2147,7 @@ static int fmeter_getrate(struct fmeter
static struct cpuset *cpuset_attach_old_cs;
-/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ +/* Called by cgroups to determine if a cpuset is usable; cpuset_rwsem held */ static int cpuset_can_attach(struct cgroup_taskset *tset) { struct cgroup_subsys_state *css; @@ -2201,7 +2203,7 @@ static void cpuset_cancel_attach(struct }
/* - * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach() + * Protected by cpuset_rwsem. cpus_attach is used only by cpuset_attach() * but we can't allocate it dynamically there. Define it global and * allocate from cpuset_init(). */ @@ -2209,7 +2211,7 @@ static cpumask_var_t cpus_attach;
static void cpuset_attach(struct cgroup_taskset *tset) { - /* static buf protected by cpuset_mutex */ + /* static buf protected by cpuset_rwsem */ static nodemask_t cpuset_attach_nodemask_to; struct task_struct *task; struct task_struct *leader; @@ -2402,7 +2404,7 @@ static ssize_t cpuset_write_resmask(stru * operation like this one can lead to a deadlock through kernfs * active_ref protection. Let's break the protection. Losing the * protection is okay as we check whether @cs is online after - * grabbing cpuset_mutex anyway. This only happens on the legacy + * grabbing cpuset_rwsem anyway. This only happens on the legacy * hierarchies. */ css_get(&cs->css); @@ -3641,7 +3643,7 @@ void __cpuset_memory_pressure_bump(void) * - Used for /proc/<pid>/cpuset. * - No need to task_lock(tsk) on this tsk->cpuset reference, as it * doesn't really matter if tsk->cpuset changes after we read it, - * and we take cpuset_mutex, keeping cpuset_attach() from changing it + * and we take cpuset_rwsem, keeping cpuset_attach() from changing it * anyway. */ int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,