diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 13 | ||||
| -rw-r--r-- | kernel/exit.c | 1 | ||||
| -rw-r--r-- | kernel/sched/auto_group.c | 36 |
3 files changed, 42 insertions, 8 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 0e292132efac..6ee1febdf6ff 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -902,6 +902,17 @@ list_update_cgroup_event(struct perf_event *event, * this will always be called from the right CPU. */ cpuctx = __get_cpu_context(ctx); + + /* Only set/clear cpuctx->cgrp if current task uses event->cgrp. */ + if (perf_cgroup_from_task(current, ctx) != event->cgrp) { + /* + * We are removing the last cpu event in this context. + * If that event is not active in this cpu, cpuctx->cgrp + * should've been cleared by perf_cgroup_switch. + */ + WARN_ON_ONCE(!add && cpuctx->cgrp); + return; + } cpuctx->cgrp = add ? event->cgrp : NULL; } @@ -8018,6 +8029,7 @@ restart: * if <size> is not specified, the range is treated as a single address. */ enum { + IF_ACT_NONE = -1, IF_ACT_FILTER, IF_ACT_START, IF_ACT_STOP, @@ -8041,6 +8053,7 @@ static const match_table_t if_tokens = { { IF_SRC_KERNEL, "%u/%u" }, { IF_SRC_FILEADDR, "%u@%s" }, { IF_SRC_KERNELADDR, "%u" }, + { IF_ACT_NONE, NULL }, }; /* diff --git a/kernel/exit.c b/kernel/exit.c index 9d68c45ebbe3..3076f3089919 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -836,6 +836,7 @@ void __noreturn do_exit(long code) */ perf_event_exit_task(tsk); + sched_autogroup_exit_task(tsk); cgroup_exit(tsk); /* diff --git a/kernel/sched/auto_group.c b/kernel/sched/auto_group.c index a5d966cb8891..f1c8fd566246 100644 --- a/kernel/sched/auto_group.c +++ b/kernel/sched/auto_group.c @@ -111,10 +111,13 @@ bool task_wants_autogroup(struct task_struct *p, struct task_group *tg) { if (tg != &root_task_group) return false; - /* - * We can only assume the task group can't go away on us if - * autogroup_move_group() can see us on ->thread_group list. + * If we race with autogroup_move_group() the caller can use the old + * value of signal->autogroup but in this case sched_move_task() will + * be called again before autogroup_kref_put(). + * + * However, there is no way sched_autogroup_exit_task() could tell us + * to avoid autogroup->tg, so we abuse PF_EXITING flag for this case. */ if (p->flags & PF_EXITING) return false; @@ -122,6 +125,16 @@ bool task_wants_autogroup(struct task_struct *p, struct task_group *tg) return true; } +void sched_autogroup_exit_task(struct task_struct *p) +{ + /* + * We are going to call exit_notify() and autogroup_move_group() can't + * see this thread after that: we can no longer use signal->autogroup. + * See the PF_EXITING check in task_wants_autogroup(). + */ + sched_move_task(p); +} + static void autogroup_move_group(struct task_struct *p, struct autogroup *ag) { @@ -138,13 +151,20 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag) } p->signal->autogroup = autogroup_kref_get(ag); - - if (!READ_ONCE(sysctl_sched_autogroup_enabled)) - goto out; - + /* + * We can't avoid sched_move_task() after we changed signal->autogroup, + * this process can already run with task_group() == prev->tg or we can + * race with cgroup code which can read autogroup = prev under rq->lock. + * In the latter case for_each_thread() can not miss a migrating thread, + * cpu_cgroup_attach() must not be possible after cgroup_exit() and it + * can't be removed from thread list, we hold ->siglock. + * + * If an exiting thread was already removed from thread list we rely on + * sched_autogroup_exit_task(). + */ for_each_thread(p, t) sched_move_task(t); -out: + unlock_task_sighand(p, &flags); autogroup_kref_put(prev); } |