On Wed, 2017-02-22 at 14:12 +0100, Peter Zijlstra wrote: > On Wed, Feb 22, 2017 at 01:56:37PM +0100, Mike Galbraith wrote: > > Hi, > > > > Do we really need a spinlock for that in the idle loop? > > Urgh, that's broken on RT, you cannot schedule the idle loop.
That's what made me notice the obnoxious little bugger. [ 77.608340] BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:995 [ 77.608342] in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1 [ 77.608343] INFO: lockdep is turned off. [ 77.608344] irq event stamp: 59222 [ 77.608353] hardirqs last enabled at (59221): [<ffffffff81105a1f>] rcu_idle_exit+0x2f/0x50 [ 77.608362] hardirqs last disabled at (59222): [<ffffffff810d4f1a>] do_idle+0x9a/0x290 [ 77.608372] softirqs last enabled at (0): [<ffffffff8107b8f1>] copy_process.part.34+0x5f1/0x22a0 [ 77.608374] softirqs last disabled at (0): [< (null)>] (null) [ 77.608374] Preemption disabled at: [ 77.608383] [<ffffffff817282b2>] schedule_preempt_disabled+0x22/0x30 [ 77.608387] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W E 4.11.0-rt9-rt #163 [ 77.608389] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014 [ 77.608390] Call Trace: [ 77.608399] dump_stack+0x85/0xc8 [ 77.608405] ___might_sleep+0x15d/0x260 [ 77.608409] rt_spin_lock+0x24/0x80 [ 77.608419] dev_pm_qos_read_value+0x1e/0x40 [ 77.608424] menu_select+0x56/0x3e0 [ 77.608426] ? rcu_eqs_enter_common.isra.40+0x9d/0x160 [ 77.608435] cpuidle_select+0x13/0x20 [ 77.608438] do_idle+0x182/0x290 [ 77.608445] cpu_startup_entry+0x48/0x50 [ 77.608450] start_secondary+0x133/0x160 [ 77.608453] start_cpu+0x14/0x14
