diff options
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 413 |
1 files changed, 225 insertions, 188 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index cfaf6419d81..3e296ed81d4 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -38,7 +38,6 @@ #include <linux/mount.h> #include <linux/namei.h> #include <linux/pagemap.h> -#include <linux/prio_heap.h> #include <linux/proc_fs.h> #include <linux/rcupdate.h> #include <linux/sched.h> @@ -56,6 +55,8 @@ #include <asm/atomic.h> #include <linux/mutex.h> #include <linux/kfifo.h> +#include <linux/workqueue.h> +#include <linux/cgroup.h> /* * Tracks how many cpusets are currently defined in system. @@ -64,7 +65,7 @@ */ int number_of_cpusets __read_mostly; -/* Retrieve the cpuset from a cgroup */ +/* Forward declare cgroup structures */ struct cgroup_subsys cpuset_subsys; struct cpuset; @@ -96,6 +97,9 @@ struct cpuset { /* partition number for rebuild_sched_domains() */ int pn; + + /* used for walking a cpuset heirarchy */ + struct list_head stack_list; }; /* Retrieve the cpuset for a cgroup */ @@ -111,7 +115,10 @@ static inline struct cpuset *task_cs(struct task_struct *task) return container_of(task_subsys_state(task, cpuset_subsys_id), struct cpuset, css); } - +struct cpuset_hotplug_scanner { + struct cgroup_scanner scan; + struct cgroup *to; +}; /* bits in struct cpuset flags field */ typedef enum { @@ -160,17 +167,17 @@ static inline int is_spread_slab(const struct cpuset *cs) * number, and avoid having to lock and reload mems_allowed unless * the cpuset they're using changes generation. * - * A single, global generation is needed because attach_task() could + * A single, global generation is needed because cpuset_attach_task() could * reattach a task to a different cpuset, which must not have its * generation numbers aliased with those of that tasks previous cpuset. * * Generations are needed for mems_allowed because one task cannot - * modify anothers memory placement. So we must enable every task, + * modify another's memory placement. So we must enable every task, * on every visit to __alloc_pages(), to efficiently check whether * its current->cpuset->mems_allowed has changed, requiring an update * of its current->mems_allowed. * - * Since cpuset_mems_generation is guarded by manage_mutex, + * Since writes to cpuset_mems_generation are guarded by the cgroup lock * there is no need to mark it atomic. */ static int cpuset_mems_generation; @@ -182,17 +189,20 @@ static struct cpuset top_cpuset = { }; /* - * We have two global cpuset mutexes below. They can nest. - * It is ok to first take manage_mutex, then nest callback_mutex. We also - * require taking task_lock() when dereferencing a tasks cpuset pointer. - * See "The task_lock() exception", at the end of this comment. + * There are two global mutexes guarding cpuset structures. The first + * is the main control groups cgroup_mutex, accessed via + * cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific + * callback_mutex, below. They can nest. It is ok to first take + * cgroup_mutex, then nest callback_mutex. 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 manage_mutex, then it blocks others wanting that mutex, + * holds cgroup_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 modify cpusets. It can perform various checks on * the cpuset structure first, knowing nothing will change. It can - * also allocate memory while just holding manage_mutex. While it is + * also allocate memory while just holding cgroup_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 everyone else. @@ -208,60 +218,16 @@ static struct cpuset top_cpuset = { * The task_struct fields mems_allowed and mems_generation may only * be accessed in the context of that task, so require no locks. * - * Any task can increment and decrement the count field without lock. - * So in general, code holding manage_mutex or callback_mutex can't rely - * on the count field not changing. However, if the count goes to - * zero, then only attach_task(), which holds both mutexes, can - * increment it again. Because a count of zero means that no tasks - * are currently attached, therefore there is no way a task attached - * to that cpuset can fork (the other way to increment the count). - * So code holding manage_mutex or callback_mutex can safely assume that - * if the count is zero, it will stay zero. Similarly, if a task - * holds manage_mutex or callback_mutex on a cpuset with zero count, it - * knows that the cpuset won't be removed, as cpuset_rmdir() needs - * both of those mutexes. - * * The cpuset_common_file_write handler for operations that modify - * the cpuset hierarchy holds manage_mutex across the entire operation, + * the cpuset hierarchy holds cgroup_mutex across the entire operation, * single threading all such cpuset modifications across the system. * * The cpuset_common_file_read() handlers only hold callback_mutex across * small pieces of code, such as when reading out possibly multi-word * cpumasks and nodemasks. * - * The fork and exit callbacks cpuset_fork() and cpuset_exit(), don't - * (usually) take either mutex. These are the two most performance - * critical pieces of code here. The exception occurs on cpuset_exit(), - * when a task in a notify_on_release cpuset exits. Then manage_mutex - * is taken, and if the cpuset count is zero, a usermode call made - * to /sbin/cpuset_release_agent with the name of the cpuset (path - * relative to the root of cpuset file system) as the argument. - * - * A cpuset can only be deleted if both its 'count' of using tasks - * is zero, and its list of 'children' cpusets is empty. Since all - * tasks in the system use _some_ cpuset, and since there is always at - * least one task in the system (init), therefore, top_cpuset - * always has either children cpusets and/or using tasks. So we don't - * need a special hack to ensure that top_cpuset cannot be deleted. - * - * The above "Tale of Two Semaphores" would be complete, but for: - * - * The task_lock() exception - * - * The need for this exception arises from the action of attach_task(), - * which overwrites one tasks cpuset pointer with another. It does - * so using both mutexes, however there are several performance - * critical places that need to reference task->cpuset without the - * expense of grabbing a system global mutex. Therefore except as - * noted below, when dereferencing or, as in attach_task(), modifying - * a tasks cpuset pointer we use task_lock(), which acts on a spinlock - * (task->alloc_lock) already in the task_struct routinely used for - * such matters. - * - * P.S. One more locking exception. RCU is used to guard the - * update of a tasks cpuset pointer by attach_task() and the - * access of task->cpuset->mems_generation via that pointer in - * the routine cpuset_update_task_memory_state(). + * Accessing a task's cpuset should be done in accordance with the + * guidelines for accessing subsystem state in kernel/cgroup.c */ static DEFINE_MUTEX(callback_mutex); @@ -354,15 +320,14 @@ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) * Do not call this routine if in_interrupt(). * * Call without callback_mutex or task_lock() held. May be - * called with or without manage_mutex held. Thanks in part to - * 'the_top_cpuset_hack', the tasks cpuset pointer will never + * called with or without cgroup_mutex held. Thanks in part to + * 'the_top_cpuset_hack', the task's cpuset pointer will never * be NULL. This routine also might acquire callback_mutex and * current->mm->mmap_sem during call. * * Reading current->cpuset->mems_generation doesn't need task_lock * to guard the current->cpuset derefence, because it is guarded - * from concurrent freeing of current->cpuset by attach_task(), - * using RCU. + * from concurrent freeing of current->cpuset using RCU. * * The rcu_dereference() is technically probably not needed, * as I don't actually mind if I see a new cpuset pointer but @@ -424,7 +389,7 @@ void cpuset_update_task_memory_state(void) * * 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 manage_mutex. + * are only set if the other's are set. Call holding cgroup_mutex. */ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) @@ -442,7 +407,7 @@ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) * 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 - * manage_mutex held. + * cgroup_mutex held. * * 'cur' is the address of an actual, in-use cpuset. Operations * such as list traversal that depend on the actual address of the @@ -476,7 +441,10 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial) if (!is_cpuset_subset(trial, par)) return -EACCES; - /* If either I or some sibling (!= me) is exclusive, we can't overlap */ + /* + * If either I or some sibling (!= me) is exclusive, we can't + * overlap + */ list_for_each_entry(cont, &par->css.cgroup->children, sibling) { c = cgroup_cs(cont); if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && @@ -732,22 +700,50 @@ static inline int started_after(void *p1, void *p2) return started_after_time(t1, &t2->start_time, t2); } -/* - * Call with manage_mutex held. May take callback_mutex during call. +/** + * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's + * @tsk: task to test + * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner + * + * Call with cgroup_mutex held. May take callback_mutex during call. + * Called for each task in a cgroup by cgroup_scan_tasks(). + * Return nonzero if this tasks's cpus_allowed mask should be changed (in other + * words, if its mask is not equal to its cpuset's mask). + */ +int cpuset_test_cpumask(struct task_struct *tsk, struct cgroup_scanner *scan) +{ + return !cpus_equal(tsk->cpus_allowed, + (cgroup_cs(scan->cg))->cpus_allowed); +} + +/** + * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's + * @tsk: task to test + * @scan: struct cgroup_scanner containing the cgroup of the task + * + * Called by cgroup_scan_tasks() for each task in a cgroup whose + * cpus_allowed mask needs to be changed. + * + * We don't need to re-check for the cgroup/cpuset membership, since we're + * holding cgroup_lock() at this point. */ +void cpuset_change_cpumask(struct task_struct *tsk, struct cgroup_scanner *scan) +{ + set_cpus_allowed(tsk, (cgroup_cs(scan->cg))->cpus_allowed); +} +/** + * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it + * @cs: the cpuset to consider + * @buf: buffer of cpu numbers written to this cpuset + */ static int update_cpumask(struct cpuset *cs, char *buf) { struct cpuset trialcs; - int retval, i; - int is_load_balanced; - struct cgroup_iter it; - struct cgroup *cgrp = cs->css.cgroup; - struct task_struct *p, *dropped; - /* Never dereference latest_task, since it's not refcounted */ - struct task_struct *latest_task = NULL; + struct cgroup_scanner scan; struct ptr_heap heap; - struct timespec latest_time = { 0, 0 }; + int retval; + int is_load_balanced; /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */ if (cs == &top_cpuset) @@ -756,7 +752,7 @@ static int update_cpumask(struct cpuset *cs, char *buf) trialcs = *cs; /* - * An empty cpus_allowed is ok iff there are no tasks in the cpuset. + * An empty cpus_allowed is ok only if the cpuset has no tasks. * Since cpulist_parse() fails on an empty mask, we special case * that parsing. The validate_change() call ensures that cpusets * with tasks have cpus. @@ -777,6 +773,7 @@ static int update_cpumask(struct cpuset *cs, char *buf) /* Nothing to do if the cpus didn't change */ if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed)) return 0; + retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, &started_after); if (retval) return retval; @@ -787,62 +784,19 @@ static int update_cpumask(struct cpuset *cs, char *buf) cs->cpus_allowed = trialcs.cpus_allowed; mutex_unlock(&callback_mutex); - again: /* * Scan tasks in the cpuset, and update the cpumasks of any - * that need an update. Since we can't call set_cpus_allowed() - * while holding tasklist_lock, gather tasks to be processed - * in a heap structure. If the statically-sized heap fills up, - * overflow tasks that started later, and in future iterations - * only consider tasks that started after the latest task in - * the previous pass. This guarantees forward progress and - * that we don't miss any tasks + * that need an update. */ - heap.size = 0; - cgroup_iter_start(cgrp, &it); - while ((p = cgroup_iter_next(cgrp, &it))) { - /* Only affect tasks that don't have the right cpus_allowed */ - if (cpus_equal(p->cpus_allowed, cs->cpus_allowed)) - continue; - /* - * Only process tasks that started after the last task - * we processed - */ - if (!started_after_time(p, &latest_time, latest_task)) - continue; - dropped = heap_insert(&heap, p); - if (dropped == NULL) { - get_task_struct(p); - } else if (dropped != p) { - get_task_struct(p); - put_task_struct(dropped); - } - } - cgroup_iter_end(cgrp, &it); - if (heap.size) { - for (i = 0; i < heap.size; i++) { - struct task_struct *p = heap.ptrs[i]; - if (i == 0) { - latest_time = p->start_time; - latest_task = p; - } - set_cpus_allowed(p, cs->cpus_allowed); - put_task_struct(p); - } - /* - * If we had to process any tasks at all, scan again - * in case some of them were in the middle of forking - * children that didn't notice the new cpumask - * restriction. Not the most efficient way to do it, - * but it avoids having to take callback_mutex in the - * fork path - */ - goto again; - } + scan.cg = cs->css.cgroup; + scan.test_task = cpuset_test_cpumask; + scan.process_task = cpuset_change_cpumask; + scan.heap = &heap; + cgroup_scan_tasks(&scan); heap_free(&heap); + if (is_load_balanced) rebuild_sched_domains(); - return 0; } @@ -854,11 +808,11 @@ static int update_cpumask(struct cpuset *cs, char *buf) * Temporarilly set tasks mems_allowed to target nodes of migration, * so that the migration code can allocate pages on these nodes. * - * Call holding manage_mutex, so our current->cpuset won't change - * during this call, as manage_mutex holds off any attach_task() + * Call holding cgroup_mutex, so current's cpuset won't change + * during this call, as manage_mutex holds off any cpuset_attach() * calls. Therefore we don't need to take task_lock around the * call to guarantee_online_mems(), as we know no one is changing - * our tasks cpuset. + * our task's cpuset. * * Hold callback_mutex around the two modifications of our tasks * mems_allowed to synchronize with cpuset_mems_allowed(). @@ -903,7 +857,7 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, * the cpuset is marked 'memory_migrate', migrate the tasks * pages to the new memory. * - * Call with manage_mutex held. May take callback_mutex during call. + * Call with cgroup_mutex held. May take callback_mutex 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. @@ -1016,7 +970,7 @@ static int update_nodemask(struct cpuset *cs, char *buf) * tasklist_lock. Forks can happen again now - the mpol_copy() * cpuset_being_rebound check will catch such forks, and rebind * their vma mempolicies too. Because we still hold the global - * cpuset manage_mutex, we know that no other rebind effort will + * cgroup_mutex, 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. @@ -1031,7 +985,7 @@ static int update_nodemask(struct cpuset *cs, char *buf) mmput(mm); } - /* We're done rebinding vma's to this cpusets new mems_allowed. */ + /* We're done rebinding vmas to this cpuset's new mems_allowed. */ kfree(mmarray); cpuset_being_rebound = NULL; retval = 0; @@ -1045,7 +999,7 @@ int current_cpuset_is_being_rebound(void) } /* - * Call with manage_mutex held. + * Call with cgroup_mutex held. */ static int update_memory_pressure_enabled(struct cpuset *cs, char *buf) @@ -1066,7 +1020,7 @@ static int update_memory_pressure_enabled(struct cpuset *cs, char *buf) * cs: the cpuset to update * buf: the buffer where we read the 0 or 1 * - * Call with manage_mutex held. + * Call with cgroup_mutex held. */ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf) @@ -1200,6 +1154,7 @@ static int fmeter_getrate(struct fmeter *fmp) return val; } +/* 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) { @@ -1547,7 +1502,8 @@ static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont) * If this becomes a problem for some users who wish to * allow that scenario, then cpuset_post_clone() could be * changed to grant parent->cpus_allowed-sibling_cpus_exclusive - * (and likewise for mems) to the new cgroup. + * (and likewise for mems) to the new cgroup. Called with cgroup_mutex + * held. */ static void cpuset_post_clone(struct cgroup_subsys *ss, struct cgroup *cgroup) @@ -1571,11 +1527,8 @@ static void cpuset_post_clone(struct cgroup_subsys *ss, /* * cpuset_create - create a cpuset - * parent: cpuset that will be parent of the new cpuset. - * name: name of the new cpuset. Will be strcpy'ed. - * mode: mode to set on new inode - * - * Must be called with the mutex on the parent inode held + * ss: cpuset cgroup subsystem + * cont: control group that the new cpuset will be part of */ static struct cgroup_subsys_state *cpuset_create( @@ -1687,53 +1640,140 @@ int __init cpuset_init(void) return 0; } +/** + * cpuset_do_move_task - move a given task to another cpuset + * @tsk: pointer to task_struct the task to move + * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner + * + * Called by cgroup_scan_tasks() for each task in a cgroup. + * Return nonzero to stop the walk through the tasks. + */ +void cpuset_do_move_task(struct task_struct *tsk, struct cgroup_scanner *scan) +{ + struct cpuset_hotplug_scanner *chsp; + + chsp = container_of(scan, struct cpuset_hotplug_scanner, scan); + cgroup_attach_task(chsp->to, tsk); +} + +/** + * move_member_tasks_to_cpuset - move tasks from one cpuset to another + * @from: cpuset in which the tasks currently reside + * @to: cpuset to which the tasks will be moved + * + * Called with cgroup_mutex held + * callback_mutex must not be held, as cpuset_attach() will take it. + * + * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, + * calling callback functions for each. + */ +static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to) +{ + struct cpuset_hotplug_scanner scan; + + scan.scan.cg = from->css.cgroup; + scan.scan.test_task = NULL; /* select all tasks in cgroup */ + scan.scan.process_task = cpuset_do_move_task; + scan.scan.heap = NULL; + scan.to = to->css.cgroup; + + if (cgroup_scan_tasks((struct cgroup_scanner *)&scan)) + printk(KERN_ERR "move_member_tasks_to_cpuset: " + "cgroup_scan_tasks failed\n"); +} + /* * If common_cpu_mem_hotplug_unplug(), below, unplugs any CPUs * or memory nodes, we need to walk over the cpuset hierarchy, * removing that CPU or node from all cpusets. If this removes the - * last CPU or node from a cpuset, then the guarantee_online_cpus() - * or guarantee_online_mems() code will use that emptied cpusets - * parent online CPUs or nodes. Cpusets that were already empty of - * CPUs or nodes are left empty. + * last CPU or node from a cpuset, then move the tasks in the empty + * cpuset to its next-highest non-empty parent. + * + * Called with cgroup_mutex held + * callback_mutex must not be held, as cpuset_attach() will take it. + */ +static void remove_tasks_in_empty_cpuset(struct cpuset *cs) +{ + struct cpuset *parent; + + /* + * The cgroup's css_sets list is in use if there are tasks + * in the cpuset; the list is empty if there are none; + * the cs->css.refcnt seems always 0. + */ + if (list_empty(&cs->css.cgroup->css_sets)) + return; + + /* + * Find its next-highest non-empty parent, (top cpuset + * has online cpus, so can't be empty). + */ + parent = cs->parent; + while (cpus_empty(parent->cpus_allowed) || + nodes_empty(parent->mems_allowed)) + parent = parent->parent; + + move_member_tasks_to_cpuset(cs, parent); +} + +/* + * Walk the specified cpuset subtree and look for empty cpusets. + * The tasks of such cpuset must be moved to a parent cpuset. * - * This routine is intentionally inefficient in a couple of regards. - * It will check all cpusets in a subtree even if the top cpuset of - * the subtree has no offline CPUs or nodes. It checks both CPUs and - * nodes, even though the caller could have been coded to know that - * only one of CPUs or nodes needed to be checked on a given call. - * This was done to minimize text size rather than cpu cycles. + * Called with cgroup_mutex held. We take callback_mutex to modify + * cpus_allowed and mems_allowed. * - * Call with both manage_mutex and callback_mutex held. + * This walk processes the tree from top to bottom, completing one layer + * before dropping down to the next. It always processes a node before + * any of its children. * - * Recursive, on depth of cpuset subtree. + * For now, since we lack memory hot unplug, we'll never see a cpuset + * that has tasks along with an empty 'mems'. But if we did see such + * a cpuset, we'd handle it just like we do if its 'cpus' was empty. */ - -static void guarantee_online_cpus_mems_in_subtree(const struct cpuset *cur) +static void scan_for_empty_cpusets(const struct cpuset *root) { + struct cpuset *cp; /* scans cpusets being updated */ + struct cpuset *child; /* scans child cpusets of cp */ + struct list_head queue; struct cgroup *cont; - struct cpuset *c; - /* Each of our child cpusets mems must be online */ - list_for_each_entry(cont, &cur->css.cgroup->children, sibling) { - c = cgroup_cs(cont); - guarantee_online_cpus_mems_in_subtree(c); - if (!cpus_empty(c->cpus_allowed)) - guarantee_online_cpus(c, &c->cpus_allowed); - if (!nodes_empty(c->mems_allowed)) - guarantee_online_mems(c, &c->mems_allowed); + INIT_LIST_HEAD(&queue); + + list_add_tail((struct list_head *)&root->stack_list, &queue); + + while (!list_empty(&queue)) { + cp = container_of(queue.next, struct cpuset, stack_list); + list_del(queue.next); + list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { + child = cgroup_cs(cont); + list_add_tail(&child->stack_list, &queue); + } + cont = cp->css.cgroup; + + /* Continue past cpusets with all cpus, mems online */ + if (cpus_subset(cp->cpus_allowed, cpu_online_map) && + nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY])) + continue; + + /* Remove offline cpus and mems from this cpuset. */ + mutex_lock(&callback_mutex); + cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map); + nodes_and(cp->mems_allowed, cp->mems_allowed, + node_states[N_HIGH_MEMORY]); + mutex_unlock(&callback_mutex); + + /* Move tasks from the empty cpuset to a parent */ + if (cpus_empty(cp->cpus_allowed) || + nodes_empty(cp->mems_allowed)) + remove_tasks_in_empty_cpuset(cp); } } /* * The cpus_allowed and mems_allowed nodemasks in the top_cpuset track * cpu_online_map and node_states[N_HIGH_MEMORY]. Force the top cpuset to - * track what's online after any CPU or memory node hotplug or unplug - * event. - * - * To ensure that we don't remove a CPU or node from the top cpuset - * that is currently in use by a child cpuset (which would violate - * the rule that cpusets must be subsets of their parent), we first - * call the recursive routine guarantee_online_cpus_mems_in_subtree(). + * track what's online after any CPU or memory node hotplug or unplug event. * * Since there are two callers of this routine, one for CPU hotplug * events and one for memory node hotplug events, we could have coded @@ -1744,13 +1784,11 @@ static void guarantee_online_cpus_mems_in_subtree(const struct cpuset *cur) static void common_cpu_mem_hotplug_unplug(void) { cgroup_lock(); - mutex_lock(&callback_mutex); - guarantee_online_cpus_mems_in_subtree(&top_cpuset); top_cpuset.cpus_allowed = cpu_online_map; top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; + scan_for_empty_cpusets(&top_cpuset); - mutex_unlock(&callback_mutex); cgroup_unlock(); } @@ -1826,7 +1864,7 @@ cpumask_t cpuset_cpus_allowed(struct task_struct *tsk) /** * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset. - * Must be called with callback_mutex held. + * Must be called with callback_mutex held. **/ cpumask_t cpuset_cpus_allowed_locked(struct task_struct *tsk) { @@ -2163,10 +2201,8 @@ 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 manage_mutex, keeping attach_task() from changing it - * anyway. No need to check that tsk->cpuset != NULL, thanks to - * the_top_cpuset_hack in cpuset_exit(), which sets an exiting tasks - * cpuset to top_cpuset. + * and we take cgroup_mutex, keeping cpuset_attach() from changing it + * anyway. */ static int proc_cpuset_show(struct seq_file *m, void *unused_v) { @@ -2219,13 +2255,14 @@ const struct file_operations proc_cpuset_operations = { #endif /* CONFIG_PROC_PID_CPUSET */ /* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */ -char *cpuset_task_status_allowed(struct task_struct *task, char *buffer) -{ - buffer += sprintf(buffer, "Cpus_allowed:\t"); - buffer += cpumask_scnprintf(buffer, PAGE_SIZE, task->cpus_allowed); - buffer += sprintf(buffer, "\n"); - buffer += sprintf(buffer, "Mems_allowed:\t"); - buffer += nodemask_scnprintf(buffer, PAGE_SIZE, task->mems_allowed); - buffer += sprintf(buffer, "\n"); - return buffer; +void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task) +{ + seq_printf(m, "Cpus_allowed:\t"); + m->count += cpumask_scnprintf(m->buf + m->count, m->size - m->count, + task->cpus_allowed); + seq_printf(m, "\n"); + seq_printf(m, "Mems_allowed:\t"); + m->count += nodemask_scnprintf(m->buf + m->count, m->size - m->count, + task->mems_allowed); + seq_printf(m, "\n"); } |