struct cpuset *parent; /* my parent */
- /*
- * Copy of global cpuset_mems_generation as of the most
- * recent time this cpuset changed its mems_allowed.
- */
- int mems_generation;
-
struct fmeter fmeter; /* memory_pressure filter */
/* partition number for rebuild_sched_domains() */
return test_bit(CS_SPREAD_SLAB, &cs->flags);
}
-/*
- * Increment this integer everytime any cpuset changes its
- * mems_allowed value. Users of cpusets can track this generation
- * 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 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 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 writes to cpuset_mems_generation are guarded by the cgroup lock
- * there is no need to mark it atomic.
- */
-static int cpuset_mems_generation;
-
static struct cpuset top_cpuset = {
.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
};
* If a task is only holding callback_mutex, then it has read-only
* access to cpusets.
*
- * The task_struct fields mems_allowed and mems_generation may only
- * be accessed in the context of that task, so require no locks.
+ * 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
* small pieces of code, such as when reading out possibly multi-word
tsk->flags &= ~PF_SPREAD_SLAB;
}
-/**
- * cpuset_update_task_memory_state - update task memory placement
- *
- * If the current tasks cpusets mems_allowed changed behind our
- * backs, update current->mems_allowed, mems_generation and task NUMA
- * mempolicy to the new value.
- *
- * Task mempolicy is updated by rebinding it relative to the
- * current->cpuset if a task has its memory placement changed.
- * Do not call this routine if in_interrupt().
- *
- * Call without callback_mutex or task_lock() held. May be
- * 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 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 using RCU.
- *
- * The rcu_dereference() is technically probably not needed,
- * as I don't actually mind if I see a new cpuset pointer but
- * an old value of mems_generation. However this really only
- * matters on alpha systems using cpusets heavily. If I dropped
- * that rcu_dereference(), it would save them a memory barrier.
- * For all other arch's, rcu_dereference is a no-op anyway, and for
- * alpha systems not using cpusets, another planned optimization,
- * avoiding the rcu critical section for tasks in the root cpuset
- * which is statically allocated, so can't vanish, will make this
- * irrelevant. Better to use RCU as intended, than to engage in
- * some cute trick to save a memory barrier that is impossible to
- * test, for alpha systems using cpusets heavily, which might not
- * even exist.
- *
- * This routine is needed to update the per-task mems_allowed data,
- * within the tasks context, when it is trying to allocate memory
- * (in various mm/mempolicy.c routines) and notices that some other
- * task has been modifying its cpuset.
- */
-
-void cpuset_update_task_memory_state(void)
-{
- int my_cpusets_mem_gen;
- struct task_struct *tsk = current;
- struct cpuset *cs;
-
- rcu_read_lock();
- my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
- rcu_read_unlock();
-
- if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
- mutex_lock(&callback_mutex);
- task_lock(tsk);
- cs = task_cs(tsk); /* Maybe changed when task not locked */
- guarantee_online_mems(cs, &tsk->mems_allowed);
- tsk->cpuset_mems_generation = cs->mems_generation;
- task_unlock(tsk);
- mutex_unlock(&callback_mutex);
- mpol_rebind_task(tsk, &tsk->mems_allowed);
- }
-}
-
/*
* is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
*
* other task, the task_struct mems_allowed that we are hacking
* is for our current task, which must allocate new pages for that
* migrating memory region.
- *
- * We call cpuset_update_task_memory_state() before hacking
- * our tasks mems_allowed, so that we are assured of being in
- * sync with our tasks cpuset, and in particular, callbacks to
- * cpuset_update_task_memory_state() from nested page allocations
- * won't see any mismatch of our cpuset and task mems_generation
- * values, so won't overwrite our hacked tasks mems_allowed
- * nodemask.
*/
static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
{
struct task_struct *tsk = current;
- cpuset_update_task_memory_state();
-
- mutex_lock(&callback_mutex);
tsk->mems_allowed = *to;
- mutex_unlock(&callback_mutex);
do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
- mutex_lock(&callback_mutex);
guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
- mutex_unlock(&callback_mutex);
}
/*
- * Rebind task's vmas to cpuset's new mems_allowed, and migrate pages to new
- * nodes if memory_migrate flag is set. Called with cgroup_mutex held.
+ * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
+ * @tsk: the task to change
+ * @newmems: new nodes that the task will be set
+ *
+ * In order to avoid seeing no nodes if the old and new nodes are disjoint,
+ * we structure updates as setting all new allowed nodes, then clearing newly
+ * disallowed ones.
+ *
+ * Called with task's alloc_lock held
+ */
+static void cpuset_change_task_nodemask(struct task_struct *tsk,
+ nodemask_t *newmems)
+{
+ nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
+ mpol_rebind_task(tsk, &tsk->mems_allowed);
+ mpol_rebind_task(tsk, newmems);
+ tsk->mems_allowed = *newmems;
+}
+
+/*
+ * Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy
+ * of it to cpuset's new mems_allowed, and migrate pages to new nodes if
+ * memory_migrate flag is set. Called with cgroup_mutex held.
*/
static void cpuset_change_nodemask(struct task_struct *p,
struct cgroup_scanner *scan)
struct cpuset *cs;
int migrate;
const nodemask_t *oldmem = scan->data;
+ nodemask_t newmems;
+
+ cs = cgroup_cs(scan->cg);
+ guarantee_online_mems(cs, &newmems);
+
+ task_lock(p);
+ cpuset_change_task_nodemask(p, &newmems);
+ task_unlock(p);
mm = get_task_mm(p);
if (!mm)
return;
- cs = cgroup_cs(scan->cg);
migrate = is_memory_migrate(cs);
mpol_rebind_mm(mm, &cs->mems_allowed);
/*
* Handle user request to change the 'mems' memory placement
* of a cpuset. Needs to validate the request, update the
- * cpusets mems_allowed and mems_generation, and for each
- * task in the cpuset, rebind any vma mempolicies and if
- * the cpuset is marked 'memory_migrate', migrate the tasks
- * pages to the new memory.
+ * cpusets mems_allowed, and for each task in the cpuset,
+ * update mems_allowed and rebind task's mempolicy and any vma
+ * mempolicies and if the cpuset is marked 'memory_migrate',
+ * migrate the tasks pages to the new memory.
*
* Call with cgroup_mutex held. May take callback_mutex during call.
* Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
mutex_lock(&callback_mutex);
cs->mems_allowed = trialcs->mems_allowed;
- cs->mems_generation = cpuset_mems_generation++;
mutex_unlock(&callback_mutex);
update_tasks_nodemask(cs, &oldmem, &heap);
if (cs == &top_cpuset) {
cpumask_copy(cpus_attach, cpu_possible_mask);
+ to = node_possible_map;
} else {
- mutex_lock(&callback_mutex);
guarantee_online_cpus(cs, cpus_attach);
- mutex_unlock(&callback_mutex);
+ guarantee_online_mems(cs, &to);
}
err = set_cpus_allowed_ptr(tsk, cpus_attach);
if (err)
return;
+ task_lock(tsk);
+ cpuset_change_task_nodemask(tsk, &to);
+ task_unlock(tsk);
cpuset_update_task_spread_flag(cs, tsk);
from = oldcs->mems_allowed;
struct cpuset *parent;
if (!cont->parent) {
- /* This is early initialization for the top cgroup */
- top_cpuset.mems_generation = cpuset_mems_generation++;
return &top_cpuset.css;
}
parent = cgroup_cs(cont->parent);
return ERR_PTR(-ENOMEM);
}
- cpuset_update_task_memory_state();
cs->flags = 0;
if (is_spread_page(parent))
set_bit(CS_SPREAD_PAGE, &cs->flags);
set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
cpumask_clear(cs->cpus_allowed);
nodes_clear(cs->mems_allowed);
- cs->mems_generation = cpuset_mems_generation++;
fmeter_init(&cs->fmeter);
cs->relax_domain_level = -1;
{
struct cpuset *cs = cgroup_cs(cont);
- cpuset_update_task_memory_state();
-
if (is_sched_load_balance(cs))
update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
.early_init = 1,
};
-/*
- * cpuset_init_early - just enough so that the calls to
- * cpuset_update_task_memory_state() in early init code
- * are harmless.
- */
-
-int __init cpuset_init_early(void)
-{
- alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_NOWAIT);
-
- top_cpuset.mems_generation = cpuset_mems_generation++;
- return 0;
-}
-
-
/**
* cpuset_init - initialize cpusets at system boot
*
{
int err = 0;
+ if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
+ BUG();
+
cpumask_setall(top_cpuset.cpus_allowed);
nodes_setall(top_cpuset.mems_allowed);
fmeter_init(&top_cpuset.fmeter);
- top_cpuset.mems_generation = cpuset_mems_generation++;
set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
top_cpuset.relax_domain_level = -1;
git://bbs.cooldavid.org / net-next-2.6.git / blobdiff