X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fcpuset.c;h=61d6af7fa6763c7b41ebba575780111761d0779a;hb=c74cba610c9559e72377fd9725a3d329581aa256;hp=43fb7e8000284bd05784ce5f30714e46075ef218;hpb=e1b8090bdf125f8b2e192149547fead7f302a89c;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 43fb7e8..61d6af7 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -872,7 +872,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, if (retval < 0) return retval; - if (!cpumask_subset(trialcs->cpus_allowed, cpu_online_mask)) + if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask)) return -EINVAL; } retval = validate_change(cs, trialcs); @@ -920,9 +920,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, * call to guarantee_online_mems(), as we know no one is changing * our task's cpuset. * - * Hold callback_mutex around the two modifications of our tasks - * mems_allowed to synchronize with cpuset_mems_allowed(). - * * While the mm_struct we are migrating is typically from some * other task, the task_struct mems_allowed that we are hacking * is for our current task, which must allocate new pages for that @@ -949,16 +946,62 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, * 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) { +repeat: + /* + * 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; + if (current->flags & PF_EXITING) /* Let dying task have memory */ + return; + + task_lock(tsk); nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); - mpol_rebind_task(tsk, &tsk->mems_allowed); - mpol_rebind_task(tsk, newmems); + mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1); + + + /* + * ensure checking ->mems_allowed_change_disable after setting all new + * allowed nodes. + * + * the read-side task can see an nodemask with new allowed nodes and + * old allowed nodes. and if it allocates page when cpuset clears newly + * disallowed ones continuous, it can see the new allowed bits. + * + * And if setting all new allowed nodes is after the checking, setting + * all new allowed nodes and clearing newly disallowed ones will be done + * continuous, and the read-side task may find no node to alloc page. + */ + smp_mb(); + + /* + * Allocation of memory is very fast, we needn't sleep when waiting + * for the read-side. + */ + while (ACCESS_ONCE(tsk->mems_allowed_change_disable)) { + task_unlock(tsk); + if (!task_curr(tsk)) + yield(); + goto repeat; + } + + /* + * ensure checking ->mems_allowed_change_disable before clearing all new + * disallowed nodes. + * + * if clearing newly disallowed bits before the checking, the read-side + * task may find no node to alloc page. + */ + smp_mb(); + + mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2); tsk->mems_allowed = *newmems; + task_unlock(tsk); } /* @@ -973,14 +1016,17 @@ static void cpuset_change_nodemask(struct task_struct *p, struct cpuset *cs; int migrate; const nodemask_t *oldmem = scan->data; - nodemask_t newmems; + NODEMASK_ALLOC(nodemask_t, newmems, GFP_KERNEL); + + if (!newmems) + return; cs = cgroup_cs(scan->cg); - guarantee_online_mems(cs, &newmems); + guarantee_online_mems(cs, newmems); + + cpuset_change_task_nodemask(p, newmems); - task_lock(p); - cpuset_change_task_nodemask(p, &newmems); - task_unlock(p); + NODEMASK_FREE(newmems); mm = get_task_mm(p); if (!mm) @@ -1051,16 +1097,21 @@ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem, static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, const char *buf) { - nodemask_t oldmem; + NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL); int retval; struct ptr_heap heap; + if (!oldmem) + return -ENOMEM; + /* * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY]; * it's read-only */ - if (cs == &top_cpuset) - return -EACCES; + if (cs == &top_cpuset) { + retval = -EACCES; + goto done; + } /* * An empty mems_allowed is ok iff there are no tasks in the cpuset. @@ -1076,11 +1127,13 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, goto done; if (!nodes_subset(trialcs->mems_allowed, - node_states[N_HIGH_MEMORY])) - return -EINVAL; + node_states[N_HIGH_MEMORY])) { + retval = -EINVAL; + goto done; + } } - oldmem = cs->mems_allowed; - if (nodes_equal(oldmem, trialcs->mems_allowed)) { + *oldmem = cs->mems_allowed; + if (nodes_equal(*oldmem, trialcs->mems_allowed)) { retval = 0; /* Too easy - nothing to do */ goto done; } @@ -1096,10 +1149,11 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, cs->mems_allowed = trialcs->mems_allowed; mutex_unlock(&callback_mutex); - update_tasks_nodemask(cs, &oldmem, &heap); + update_tasks_nodemask(cs, oldmem, &heap); heap_free(&heap); done: + NODEMASK_FREE(oldmem); return retval; } @@ -1373,9 +1427,7 @@ static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to, err = set_cpus_allowed_ptr(tsk, cpus_attach); WARN_ON_ONCE(err); - task_lock(tsk); cpuset_change_task_nodemask(tsk, to); - task_unlock(tsk); cpuset_update_task_spread_flag(cs, tsk); } @@ -1384,40 +1436,47 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct cgroup *oldcont, struct task_struct *tsk, bool threadgroup) { - nodemask_t from, to; 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); - to = node_possible_map; } else { guarantee_online_cpus(cs, cpus_attach); - guarantee_online_mems(cs, &to); } + guarantee_online_mems(cs, to); /* do per-task migration stuff possibly for each in the threadgroup */ - cpuset_attach_task(tsk, &to, cs); + 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); + 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; + *from = oldcs->mems_allowed; + *to = cs->mems_allowed; mm = get_task_mm(tsk); if (mm) { - mpol_rebind_mm(mm, &to); + mpol_rebind_mm(mm, to); if (is_memory_migrate(cs)) - cpuset_migrate_mm(mm, &from, &to); + cpuset_migrate_mm(mm, from, to); mmput(mm); } + +alloc_fail: + NODEMASK_FREE(from); + NODEMASK_FREE(to); } /* The various types of files and directories in a cpuset file system */ @@ -1562,13 +1621,21 @@ static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs) static int cpuset_sprintf_memlist(char *page, struct cpuset *cs) { - nodemask_t mask; + NODEMASK_ALLOC(nodemask_t, mask, GFP_KERNEL); + int retval; + + if (mask == NULL) + return -ENOMEM; mutex_lock(&callback_mutex); - mask = cs->mems_allowed; + *mask = cs->mems_allowed; mutex_unlock(&callback_mutex); - return nodelist_scnprintf(page, PAGE_SIZE, mask); + retval = nodelist_scnprintf(page, PAGE_SIZE, *mask); + + NODEMASK_FREE(mask); + + return retval; } static ssize_t cpuset_common_file_read(struct cgroup *cont, @@ -1997,7 +2064,10 @@ static void scan_for_empty_cpusets(struct cpuset *root) struct cpuset *cp; /* scans cpusets being updated */ struct cpuset *child; /* scans child cpusets of cp */ struct cgroup *cont; - nodemask_t oldmems; + NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL); + + if (oldmems == NULL) + return; list_add_tail((struct list_head *)&root->stack_list, &queue); @@ -2010,16 +2080,16 @@ static void scan_for_empty_cpusets(struct cpuset *root) } /* Continue past cpusets with all cpus, mems online */ - if (cpumask_subset(cp->cpus_allowed, cpu_online_mask) && + if (cpumask_subset(cp->cpus_allowed, cpu_active_mask) && nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY])) continue; - oldmems = cp->mems_allowed; + *oldmems = cp->mems_allowed; /* Remove offline cpus and mems from this cpuset. */ mutex_lock(&callback_mutex); cpumask_and(cp->cpus_allowed, cp->cpus_allowed, - cpu_online_mask); + cpu_active_mask); nodes_and(cp->mems_allowed, cp->mems_allowed, node_states[N_HIGH_MEMORY]); mutex_unlock(&callback_mutex); @@ -2030,9 +2100,10 @@ static void scan_for_empty_cpusets(struct cpuset *root) remove_tasks_in_empty_cpuset(cp); else { update_tasks_cpumask(cp, NULL); - update_tasks_nodemask(cp, &oldmems, NULL); + update_tasks_nodemask(cp, oldmems, NULL); } } + NODEMASK_FREE(oldmems); } /* @@ -2057,8 +2128,10 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb, switch (phase) { case CPU_ONLINE: case CPU_ONLINE_FROZEN: - case CPU_DEAD: - case CPU_DEAD_FROZEN: + case CPU_DOWN_PREPARE: + case CPU_DOWN_PREPARE_FROZEN: + case CPU_DOWN_FAILED: + case CPU_DOWN_FAILED_FROZEN: break; default: @@ -2067,7 +2140,7 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb, cgroup_lock(); mutex_lock(&callback_mutex); - cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask); + cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); mutex_unlock(&callback_mutex); scan_for_empty_cpusets(&top_cpuset); ndoms = generate_sched_domains(&doms, &attr); @@ -2088,20 +2161,33 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb, static int cpuset_track_online_nodes(struct notifier_block *self, unsigned long action, void *arg) { + NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL); + + if (oldmems == NULL) + return NOTIFY_DONE; + cgroup_lock(); switch (action) { case MEM_ONLINE: - case MEM_OFFLINE: + *oldmems = top_cpuset.mems_allowed; mutex_lock(&callback_mutex); top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; mutex_unlock(&callback_mutex); - if (action == MEM_OFFLINE) - scan_for_empty_cpusets(&top_cpuset); + update_tasks_nodemask(&top_cpuset, oldmems, NULL); + break; + case MEM_OFFLINE: + /* + * needn't update top_cpuset.mems_allowed explicitly because + * scan_for_empty_cpusets() will update it. + */ + scan_for_empty_cpusets(&top_cpuset); break; default: break; } cgroup_unlock(); + + NODEMASK_FREE(oldmems); return NOTIFY_OK; } #endif @@ -2114,7 +2200,7 @@ static int cpuset_track_online_nodes(struct notifier_block *self, void __init cpuset_init_smp(void) { - cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask); + cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; hotcpu_notifier(cpuset_track_online_cpus, 0); @@ -2138,19 +2224,52 @@ void __init cpuset_init_smp(void) void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) { mutex_lock(&callback_mutex); - cpuset_cpus_allowed_locked(tsk, pmask); + task_lock(tsk); + guarantee_online_cpus(task_cs(tsk), pmask); + task_unlock(tsk); mutex_unlock(&callback_mutex); } -/** - * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset. - * Must be called with callback_mutex held. - **/ -void cpuset_cpus_allowed_locked(struct task_struct *tsk, struct cpumask *pmask) +int cpuset_cpus_allowed_fallback(struct task_struct *tsk) { - task_lock(tsk); - guarantee_online_cpus(task_cs(tsk), pmask); - task_unlock(tsk); + const struct cpuset *cs; + int cpu; + + rcu_read_lock(); + cs = task_cs(tsk); + if (cs) + cpumask_copy(&tsk->cpus_allowed, cs->cpus_allowed); + rcu_read_unlock(); + + /* + * We own tsk->cpus_allowed, nobody can change it under us. + * + * But we used cs && cs->cpus_allowed lockless and thus can + * race with cgroup_attach_task() or update_cpumask() and get + * the wrong tsk->cpus_allowed. However, both cases imply the + * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr() + * which takes task_rq_lock(). + * + * If we are called after it dropped the lock we must see all + * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary + * set any mask even if it is not right from task_cs() pov, + * the pending set_cpus_allowed_ptr() will fix things. + */ + + cpu = cpumask_any_and(&tsk->cpus_allowed, cpu_active_mask); + if (cpu >= nr_cpu_ids) { + /* + * Either tsk->cpus_allowed is wrong (see above) or it + * is actually empty. The latter case is only possible + * if we are racing with remove_tasks_in_empty_cpuset(). + * Like above we can temporary set any mask and rely on + * set_cpus_allowed_ptr() as synchronization point. + */ + cpumask_copy(&tsk->cpus_allowed, cpu_possible_mask); + cpu = cpumask_any(cpu_active_mask); + } + + return cpu; } void cpuset_init_current_mems_allowed(void) @@ -2339,22 +2458,6 @@ int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask) } /** - * cpuset_lock - lock out any changes to cpuset structures - * - * The out of memory (oom) code needs to mutex_lock cpusets - * from being changed while it scans the tasklist looking for a - * task in an overlapping cpuset. Expose callback_mutex via this - * cpuset_lock() routine, so the oom code can lock it, before - * locking the task list. The tasklist_lock is a spinlock, so - * must be taken inside callback_mutex. - */ - -void cpuset_lock(void) -{ - mutex_lock(&callback_mutex); -} - -/** * cpuset_unlock - release lock on cpuset changes * * Undo the lock taken in a previous cpuset_lock() call.