Hi Chirag Chirag Jog wrote: > Hi Gregory, > We see the following BUG followed by a hang on the latest kernel 2.6.26.5-rt9 on a Power6 blade (PPC64) > It is easily recreated by running the async_handler or sbrk_mutex (realtime tests from ltp) tests. > FYI I am looking at this now. I suspect a dequeue_pushable_task() probably found its way inside a conditional for GROUP_SCHED and inadventently gets compiled away if you disable the feature. Investigating now.. -Greg > login: cpu 0x2: Vector: 700 (Program Check) at [c0000000e8e875d0] > pc: c00000000005110c: .pick_next_pushable_task+0x54/0x9c > lr: c000000000059f50: .push_rt_task+0x44/0x2b4 > sp: c0000000e8e87850 > msr: 8000000000021032 > current = 0xc0000000ea5bb2e0 > paca = 0xc000000000608700 > pid = 2811, comm = async_handler > kernel BUG at kernel/sched_rt.c:1041! <--------------------- > enter ? for help > [link register ] c000000000059f50 .push_rt_task+0x44/0x2b4 > [c0000000e8e87850] c0000000e8e878f0 (unreliable) > [c0000000e8e87900] c00000000005a1dc .push_rt_tasks+0x1c/0x38 > [c0000000e8e87980] c00000000005a21c .post_schedule_rt+0x24/0x44 > [c0000000e8e87a10] c000000000057cbc .finish_task_switch+0xd0/0x180 > [c0000000e8e87ab0] c0000000003b6e88 .__schedule+0x6e0/0x798 > [c0000000e8e87b90] c0000000003b7148 .schedule+0xec/0x11c > [c0000000e8e87c10] c0000000003b7a40 .do_nanosleep+0x6c/0xcc > [c0000000e8e87c90] c000000000080738 .hrtimer_nanosleep+0x7c/0x100 > [c0000000e8e87d90] c000000000080830 .sys_nanosleep+0x74/0x94 > [c0000000e8e87e30] c0000000000086ac syscall_exit+0x0/0x40 > --- Exception: c00 (System Call) at 0000008026449844 > SP (400014185f0) is in userspace > > > This is generated by the BUG_ON lines in the pick_next_pushable function > introduced by the sched-only-push-once-per-queue.patch . > > The -rt kernel prior to this patch didnot give such BUGes. > > All this was tried with > CONFIG_GROUP_SCHED=N > CONFIG_RT_GROUP_SCHED=N > > > Setting the options > CONFIG_GROUP_SCHED=y > CONFIG_RT_GROUP_SCHED=Y, > seems to solve the problem. > > > >
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