On 14/06/18 09:33, Steven Rostedt wrote: > On Wed, 13 Jun 2018 14:17:07 +0200 > Juri Lelli <juri.le...@redhat.com> wrote: > > > From: Mathieu Poirier <mathieu.poir...@linaro.org> > > > > The comment above function partition_sched_domains() clearly state that > > the cpu_hotplug_lock should be held but doesn't mandate one to abide to > > it. > > > > Add an explicit check backing that comment, so to make it impossible > > for anyone to miss the requirement. > > > > Suggested-by: Juri Lelli <juri.le...@redhat.com> > > Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org> > > [modified changelog] > > Signed-off-by: Juri Lelli <juri.le...@redhat.com> > > Reviewed-by: Steven Rostedt (VMware) <rost...@goodmis.org> > > -- Steve > > > --- > > kernel/sched/topology.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > > index 61a1125c1ae4..96eee22fafe8 100644 > > --- a/kernel/sched/topology.c > > +++ b/kernel/sched/topology.c > > @@ -1858,6 +1858,7 @@ void partition_sched_domains(int ndoms_new, > > cpumask_var_t doms_new[], > > int i, j, n; > > int new_topology; > > > > + lockdep_assert_cpus_held(); > > mutex_lock(&sched_domains_mutex); > > > > /* Always unregister in case we don't destroy any domains: */
Thanks for reviewing Steve. I thought this should be fine (also looking at the comment before the function), but then got this from 0day [ 2.206129] .................................... done. [ 2.206662] Using IPI No-Shortcut mode [ 2.207084] sched_clock: Marking stable (2200014216, 0)->(2435550722, -235536506) [ 2.208792] registered taskstats version 1 [ 2.209251] page_owner is disabled [ 2.290164] WARNING: CPU: 0 PID: 13 at kernel/cpu.c:311 lockdep_assert_cpus_held+0x22/0x26 [ 2.291253] Modules linked in: [ 2.291589] CPU: 0 PID: 13 Comm: cpuhp/0 Not tainted 4.17.0-rc6-00217-gebf44b4 #2 [ 2.292367] EIP: lockdep_assert_cpus_held+0x22/0x26 [ 2.292882] EFLAGS: 00210246 CPU: 0 [ 2.293255] EAX: 00000000 EBX: 00000000 ECX: c1b1fd98 EDX: 00200286 [ 2.293915] ESI: 00000000 EDI: c1b1fcb4 EBP: dd8a3e60 ESP: dd8a3e60 [ 2.294578] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 2.295128] CR0: 80050033 CR2: 00000000 CR3: 01c9d000 CR4: 000006d0 [ 2.295770] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ 2.296409] DR6: fffe0ff0 DR7: 00000400 [ 2.296802] Call Trace: [ 2.297066] partition_sched_domains+0x1b/0x29f [ 2.297557] ? dl_cpu_busy+0x1b5/0x1c6 [ 2.297955] sched_cpu_deactivate+0x8b/0xb6 [ 2.298403] ? call_rcu_bh+0x17/0x17 [ 2.298786] ? call_rcu_bh+0x17/0x17 [ 2.299170] ? rcu_read_lock_bh_held+0x55/0x55 [ 2.299648] ? sched_cpu_activate+0xcc/0xcc [ 2.300076] cpuhp_invoke_callback+0x19d/0x978 [ 2.300537] cpuhp_thread_fun+0x125/0x16b [ 2.300949] smpboot_thread_fn+0x192/0x1a6 [ 2.301377] kthread+0xfc/0x101 [ 2.301703] ? sort_range+0x1d/0x1d [ 2.302062] ? kthread_flush_work_fn+0x12/0x12 [ 2.302524] ret_from_fork+0x2e/0x40 [ 2.302891] Code: ff 83 c4 10 5b 5e 5f 5d c3 55 89 e5 e8 ca dc fe ff 83 3d 20 bc b4 c1 00 74 13 83 ca ff b8 98 fd b1 c1 e8 e2 4b 04 00 85 c0 75 02 <0f> 0b 5d c3 55 89 e5 56 53 e8 a2 dc fe ff 89 c6 3b 05 8c 40 bd [ 2.304975] irq event stamp: 308 [ 2.305335] hardirqs last enabled at (307): [<c179d83c>] _raw_spin_unlock_irqrestore+0x4a/0x68 [ 2.306195] hardirqs last disabled at (308): [<c179ed38>] common_exception+0x46/0x6e [ 2.306969] softirqs last enabled at (0): [<c10448e6>] copy_process+0x582/0x16c5 [ 2.307720] softirqs last disabled at (0): [<00000000>] (null) [ 2.308328] ---[ end trace 7197acb79221f1b9 ]--- Guess early boot is "special"? :-/ Best, - Juri
