Commit-ID: 985d3a4c11cd28251bcc7925aa2d7a9038910384 Gitweb: http://git.kernel.org/tip/985d3a4c11cd28251bcc7925aa2d7a9038910384 Author: Yuyang Du <[email protected]> AuthorDate: Mon, 6 Jul 2015 06:11:51 +0800 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 3 Aug 2015 12:21:19 +0200
sched/fair: Avoid pulling all tasks in idle balancing In idle balancing where a CPU going idle pulls tasks from another CPU, a livelock may happen if the CPU pulls all tasks from another, makes it idle, and this iterates. So just avoid this. Reported-by: Rabin Vincent <[email protected]> Signed-off-by: Yuyang Du <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Ben Segall <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Morten Rasmussen <[email protected]> Cc: Paul Turner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/sched/fair.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 587a2f6..8b384b8d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5863,6 +5863,13 @@ static int detach_tasks(struct lb_env *env) return 0; while (!list_empty(tasks)) { + /* + * We don't want to steal all, otherwise we may be treated likewise, + * which could at worst lead to a livelock crash. + */ + if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1) + break; + p = list_first_entry(tasks, struct task_struct, se.group_node); env->loop++; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
