diff options
| author |   Yuyang Du <yuyang.du@intel.com> | 2015-07-06 06:11:51 +0800 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-08-03 12:21:19 +0200 |
| commit | 985d3a4c11cd28251bcc7925aa2d7a9038910384 (patch) | |
| tree | f93f877988e036e804150ff1b4427c66ba56facc /kernel/sched | |
| parent | sched/idle: Move latency tracing stop/start calls deeper inside the idle loop (diff) | |
| download | linux-dev-985d3a4c11cd28251bcc7925aa2d7a9038910384.tar.xz linux-dev-985d3a4c11cd28251bcc7925aa2d7a9038910384.zip | |
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.vincent@axis.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150705221151.GF5197@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 587a2f67ceb1..8b384b8d2f1d 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++; |