4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Wanpeng Li <[email protected]> [ Upstream commit a499c3ead88ccf147fc50689e85a530ad923ce36 ] This is triggered during boot when CONFIG_SCHED_DEBUG is enabled: ------------[ cut here ]------------ WARNING: CPU: 6 PID: 81 at kernel/sched/sched.h:812 set_next_entity+0x11d/0x380 rq->clock_update_flags < RQCF_ACT_SKIP CPU: 6 PID: 81 Comm: torture_shuffle Not tainted 4.10.0+ #1 Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY, BIOS FBKTC1AUS 02/16/2016 Call Trace: dump_stack+0x85/0xc2 __warn+0xcb/0xf0 warn_slowpath_fmt+0x5f/0x80 set_next_entity+0x11d/0x380 set_curr_task_fair+0x2b/0x60 do_set_cpus_allowed+0x139/0x180 __set_cpus_allowed_ptr+0x113/0x260 set_cpus_allowed_ptr+0x10/0x20 torture_shuffle+0xfd/0x180 kthread+0x10f/0x150 ? torture_shutdown_init+0x60/0x60 ? kthread_create_on_node+0x60/0x60 ret_from_fork+0x31/0x40 ---[ end trace dd94d92344cea9c6 ]--- The task is running && !queued, so there is no rq clock update before calling set_curr_task(). This patch fixes it by updating rq clock after holding rq->lock/pi_lock just as what other dequeue + put_prev + enqueue + set_curr story does. Signed-off-by: Wanpeng Li <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Matt Fleming <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[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]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1141,6 +1141,7 @@ static int __set_cpus_allowed_ptr(struct int ret = 0; rq = task_rq_lock(p, &rf); + update_rq_clock(rq); if (p->flags & PF_KTHREAD) { /*
