Commit-ID: 067491b7313c41f49607fce782d29344d1472587 Gitweb: http://git.kernel.org/tip/067491b7313c41f49607fce782d29344d1472587 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Wed, 7 Dec 2011 14:32:08 +0100 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Thu, 8 Dec 2011 05:45:48 +0100 sched, nohz: Fix missing RCU read lock Yong Zhang reported: > [ INFO: suspicious RCU usage. ] > kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage! This is due to the sched_domain stuff being RCU protected and commit 0b005cf5 ("sched, nohz: Implement sched group, domain aware nohz idle load balancing") overlooking this fact. The sd variable only lives inside the for_each_domain() block, so we only need to wrap that. Reported-by: Yong Zhang <yong.zhang0@xxxxxxxxx> Tested-by: Yong Zhang <yong.zhang0@xxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> Link: http://lkml.kernel.org/r/1323264728.32012.107.camel@twins Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/sched/fair.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6482136..a4d2b7a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5088,23 +5088,28 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) if (rq->nr_running >= 2) goto need_kick; + rcu_read_lock(); for_each_domain(cpu, sd) { struct sched_group *sg = sd->groups; struct sched_group_power *sgp = sg->sgp; int nr_busy = atomic_read(&sgp->nr_busy_cpus); if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1) - goto need_kick; + goto need_kick_unlock; if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight && (cpumask_first_and(nohz.idle_cpus_mask, sched_domain_span(sd)) < cpu)) - goto need_kick; + goto need_kick_unlock; if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING))) break; } + rcu_read_unlock(); return 0; + +need_kick_unlock: + rcu_read_unlock(); need_kick: return 1; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html