From: Peter Zijlstra Date: Mon, 18 Feb 2008 12:39:37 +0000 (+0100) Subject: sched: fix regression with sched yield X-Git-Tag: firefly_0821_release~21609^2~50 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=79b3feffb10417f197d2ab48dd4fa3c0c9e7d788;p=firefly-linux-kernel-4.4.55.git sched: fix regression with sched yield Balbir Singh reported: > 1:mon> t > [c0000000e7677da0] c000000000067de0 .sys_sched_yield+0x6c/0xbc > [c0000000e7677e30] c000000000008748 syscall_exit+0x0/0x40 > --- Exception: c01 (System Call) at 00000400001d09e4 > SP (4000664cb10) is in userspace > 1:mon> r > cpu 0x1: Vector: 300 (Data Access) at [c0000000e7677aa0] > pc: c000000000068e50: .yield_task_fair+0x94/0xc4 > lr: c000000000067de0: .sys_sched_yield+0x6c/0xbc the check that should have avoided that is: /* * Are we the only task in the tree? */ if (unlikely(rq->load.weight == curr->se.load.weight)) return; But I guess that overlooks rt tasks, they also increase the load. So I guess something like this ought to fix it.. Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index bedda18f37a5..290cf770b712 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -904,7 +904,7 @@ static void yield_task_fair(struct rq *rq) /* * Already in the rightmost position? */ - if (unlikely(rightmost->vruntime < se->vruntime)) + if (unlikely(!rightmost || rightmost->vruntime < se->vruntime)) return; /*