On 05/09/18 16:47, Olaf Hering wrote: > Am Wed, 5 Sep 2018 12:55:58 +0200 > schrieb Juergen Gross <[email protected]>: > >> Instead of trying to fight the symptoms, I think avoiding to offline >> the last cpu would make more sense. > > Well, apparently the fix is to leave cpu#0 online because of a backtrace like > that:
I'd go with testing whether cpu_is_hotpluggable(cpu) returns true. Per default this will return false for cpu 0. Additionally I'd really like a test for num_online_cpus() > 1 BTW: I'm not sure this WARN triggers because it is cpu#0. Are you sure the tested cpu in that WARN was 0? After all the test is just running on cpu#0 and I don't think it can be offline already. Juergen > > WARNING: CPU: 0 PID: 83 at kernel/sched/cpudeadline.c:159 > cpudl_clear+0xa5/0xb0 > Workqueue: events cpuset_hotplug_workfn > RIP: e030:cpudl_clear+0xa5/0xb0 > Code: 8b 43 48 c7 44 28 0c ff ff ff ff e8 d5 fd ff ff 48 8d 43 08 f0 4c 0f ab > 20 4c 89 ee 48 89 df 5b 5d 41 5c 41 5d e9 0b 3b 79 00 <0f> 0b e9 76 ff ff ff > 0f 1f 40 00 66 66 66 66 90 41 56 49 89 d6 41 > RSP: e02b:ffffc900411cbc40 EFLAGS: 00010086 > RAX: ffffffff810d09a0 RBX: ffff880106f1a100 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880106f1a100 > RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8801068989b0 > R10: ffff8801068989d0 R11: 0000000000000008 R12: 0000000000000000 > R13: ffff8801f3800200 R14: 0000000000000001 R15: ffff8801f3823240 > FS: 00007fd40d7f08c0(0000) GS:ffff8801f3800000(0000) knlGS:0000000000000000 > CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000055eff60fe098 CR3: 00000001edf24000 CR4: 0000000000002660 > Call Trace: > rq_offline_dl+0x36/0x80 > set_rq_offline+0x31/0x60 > rq_attach_root+0x98/0xc0 > cpu_attach_domain+0x107/0x320 > partition_sched_domains+0x117/0x347 > ? cpus_read_lock+0x2d/0x50 > rebuild_sched_domains_locked+0xe4/0x4e0 > ? __switch_to_asm+0x40/0x70 > ? xen_mc_flush+0x102/0x210 > rebuild_sched_domains+0x16/0x30 > cpuset_hotplug_workfn+0x45e/0xef0 > ? _raw_spin_unlock_irq+0x22/0x40 > ? finish_task_switch+0x75/0x250 > process_one_work+0x1fd/0x3e0 > worker_thread+0x2d/0x3d0 > ? rescuer_thread+0x340/0x340 > kthread+0x112/0x130 > ? kthread_create_worker_on_cpu+0x40/0x40 > ret_from_fork+0x3a/0x50 > > Initially I did not spot it because the kernel was booted with 'quiet'. > > Olaf > _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
