From a0f98a1cb7d27c656de450ba56efd31bdc59065e Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 17 Jun 2007 18:37:45 +0200 Subject: [PATCH] sched: fix SysRq-N (normalize RT tasks) Gene Heskett reported the following problem while testing CFS: SysRq-N is not always effective in normalizing tasks back to SCHED_OTHER. The reason for that turns out to be the following bug: - normalize_rt_tasks() uses for_each_process() to iterate through all tasks in the system. The problem is, this method does not iterate through all tasks, it iterates through all thread groups. The proper mechanism to enumerate over all threads is to use a do_each_thread() + while_each_thread() loop. Reported-by: Gene Heskett Signed-off-by: Ingo Molnar Signed-off-by: Linus Torvalds --- kernel/sched.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 13cdab3b4c4..49be34e1f0b 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -7071,12 +7071,13 @@ EXPORT_SYMBOL(__might_sleep); void normalize_rt_tasks(void) { struct prio_array *array; - struct task_struct *p; + struct task_struct *g, *p; unsigned long flags; struct rq *rq; read_lock_irq(&tasklist_lock); - for_each_process(p) { + + do_each_thread(g, p) { if (!rt_task(p)) continue; @@ -7094,7 +7095,8 @@ void normalize_rt_tasks(void) __task_rq_unlock(rq); spin_unlock_irqrestore(&p->pi_lock, flags); - } + } while_each_thread(g, p); + read_unlock_irq(&tasklist_lock); } -- 2.41.1