Commit-ID: 985d3a4c11cd28251bcc7925aa2d7a9038910384 Gitweb: http://git.kernel.org/tip/985d3a4c11cd28251bcc7925aa2d7a9038910384 Author: Yuyang Du <yuyang...@intel.com> AuthorDate: Mon, 6 Jul 2015 06:11:51 +0800 Committer: Ingo Molnar <mi...@kernel.org> 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 <rabin.vinc...@axis.com> Signed-off-by: Yuyang Du <yuyang...@intel.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Ben Segall <bseg...@google.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mike Galbraith <efa...@gmx.de> Cc: Mike Galbraith <umgwanakikb...@gmail.com> Cc: Morten Rasmussen <morten.rasmus...@arm.com> Cc: Paul Turner <p...@google.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/20150705221151.gf5...@intel.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
