Messages in this thread | | | Date | Fri, 24 Oct 2014 19:29:43 +0300 | From | Yanko Kaneti <> | Subject | Re: localed stuck in recent 3.18 git in copy_net_ns? |
| |
On Fri-10/24/14-2014 08:40, Paul E. McKenney wrote: > On Fri, Oct 24, 2014 at 12:08:57PM +0300, Yanko Kaneti wrote: > > On Thu-10/23/14-2014 15:04, Paul E. McKenney wrote: > > > On Fri, Oct 24, 2014 at 12:45:40AM +0300, Yanko Kaneti wrote: > > > > > > > > On Thu, 2014-10-23 at 13:05 -0700, Paul E. McKenney wrote: > > > > > On Thu, Oct 23, 2014 at 10:51:59PM +0300, Yanko Kaneti wrote: > > [ . . . ] > > > > > > > Indeed, c847f14217d5 it is. > > > > > > > > > > > > Much to my embarrasment I just noticed that in addition to the > > > > > > rcu merge, triggering the bug "requires" my specific Fedora > > > > > > rawhide network > > > > > > setup. Booting in single mode and modprobe ppp_generic is fine. > > > > > > The bug > > > > > > appears when starting with my regular fedora network setup, which > > > > > > in my case > > > > > > includes 3 ethernet adapters and a libvirt birdge+nat setup. > > > > > > > > > > > > Hope that helps. > > > > > > > > > > > > I am attaching the config. > > > > > > > > > > It does help a lot, thank you!!! > > > > > > > > > > The following patch is a bit of a shot in the dark, and assumes that > > > > > commit 1772947bd012 (rcu: Handle NOCB callbacks from irq-disabled > > > > > idle > > > > > code) introduced the problem. Does this patch fix things up? > > > > > > > > Unfortunately not, This is linus-tip + patch > > > > > > OK. Can't have everything, I guess. > > > > > > > INFO: task kworker/u16:6:96 blocked for more than 120 seconds. > > > > Not tainted 3.18.0-rc1+ #4 > > > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > > kworker/u16:6 D ffff8800ca84cec0 11168 96 2 0x00000000 > > > > Workqueue: netns cleanup_net > > > > ffff8802218339e8 0000000000000096 ffff8800ca84cec0 00000000001d5f00 > > > > ffff880221833fd8 00000000001d5f00 ffff880223264ec0 ffff8800ca84cec0 > > > > ffffffff82c52040 7fffffffffffffff ffffffff81ee2658 ffffffff81ee2650 > > > > Call Trace: > > > > [<ffffffff8185b8e9>] schedule+0x29/0x70 > > > > [<ffffffff81860b0c>] schedule_timeout+0x26c/0x410 > > > > [<ffffffff81028bea>] ? native_sched_clock+0x2a/0xa0 > > > > [<ffffffff8110759c>] ? mark_held_locks+0x7c/0xb0 > > > > [<ffffffff81861b90>] ? _raw_spin_unlock_irq+0x30/0x50 > > > > [<ffffffff8110772d>] ? trace_hardirqs_on_caller+0x15d/0x200 > > > > [<ffffffff8185d31c>] wait_for_completion+0x10c/0x150 > > > > [<ffffffff810e4ed0>] ? wake_up_state+0x20/0x20 > > > > [<ffffffff8112a219>] _rcu_barrier+0x159/0x200 > > > > [<ffffffff8112a315>] rcu_barrier+0x15/0x20 > > > > [<ffffffff8171657f>] netdev_run_todo+0x6f/0x310 > > > > [<ffffffff8170b145>] ? rollback_registered_many+0x265/0x2e0 > > > > [<ffffffff817235ee>] rtnl_unlock+0xe/0x10 > > > > [<ffffffff8170cfa6>] default_device_exit_batch+0x156/0x180 > > > > [<ffffffff810fd390>] ? abort_exclusive_wait+0xb0/0xb0 > > > > [<ffffffff81705053>] ops_exit_list.isra.1+0x53/0x60 > > > > [<ffffffff81705c00>] cleanup_net+0x100/0x1f0 > > > > [<ffffffff810cca98>] process_one_work+0x218/0x850 > > > > [<ffffffff810cc9ff>] ? process_one_work+0x17f/0x850 > > > > [<ffffffff810cd1b7>] ? worker_thread+0xe7/0x4a0 > > > > [<ffffffff810cd13b>] worker_thread+0x6b/0x4a0 > > > > [<ffffffff810cd0d0>] ? process_one_work+0x850/0x850 > > > > [<ffffffff810d348b>] kthread+0x10b/0x130 > > > > [<ffffffff81028c69>] ? sched_clock+0x9/0x10 > > > > [<ffffffff810d3380>] ? kthread_create_on_node+0x250/0x250 > > > > [<ffffffff818628bc>] ret_from_fork+0x7c/0xb0 > > > > [<ffffffff810d3380>] ? kthread_create_on_node+0x250/0x250 > > > > 4 locks held by kworker/u16:6/96: > > > > #0: ("%s""netns"){.+.+.+}, at: [<ffffffff810cc9ff>] process_one_work+0x17f/0x850 > > > > #1: (net_cleanup_work){+.+.+.}, at: [<ffffffff810cc9ff>] process_one_work+0x17f/0x850 > > > > #2: (net_mutex){+.+.+.}, at: [<ffffffff81705b8c>] cleanup_net+0x8c/0x1f0 > > > > #3: (rcu_sched_state.barrier_mutex){+.+...}, at: [<ffffffff8112a0f5>] _rcu_barrier+0x35/0x200 > > > > INFO: task modprobe:1045 blocked for more than 120 seconds. > > > > Not tainted 3.18.0-rc1+ #4 > > > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > > modprobe D ffff880218343480 12920 1045 1044 0x00000080 > > > > ffff880218353bf8 0000000000000096 ffff880218343480 00000000001d5f00 > > > > ffff880218353fd8 00000000001d5f00 ffffffff81e1b580 ffff880218343480 > > > > ffff880218343480 ffffffff81f8f748 0000000000000246 ffff880218343480 > > > > Call Trace: > > > > [<ffffffff8185be91>] schedule_preempt_disabled+0x31/0x80 > > > > [<ffffffff8185d6e3>] mutex_lock_nested+0x183/0x440 > > > > [<ffffffff81705a1f>] ? register_pernet_subsys+0x1f/0x50 > > > > [<ffffffff81705a1f>] ? register_pernet_subsys+0x1f/0x50 > > > > [<ffffffffa0673000>] ? 0xffffffffa0673000 > > > > [<ffffffff81705a1f>] register_pernet_subsys+0x1f/0x50 > > > > [<ffffffffa0673048>] br_init+0x48/0xd3 [bridge] > > > > [<ffffffff81002148>] do_one_initcall+0xd8/0x210 > > > > [<ffffffff81153052>] load_module+0x20c2/0x2870 > > > > [<ffffffff8114e030>] ? store_uevent+0x70/0x70 > > > > [<ffffffff81278717>] ? kernel_read+0x57/0x90 > > > > [<ffffffff811539e6>] SyS_finit_module+0xa6/0xe0 > > > > [<ffffffff81862969>] system_call_fastpath+0x12/0x17 > > > > 1 lock held by modprobe/1045: > > > > #0: (net_mutex){+.+.+.}, at: [<ffffffff81705a1f>] register_pernet_subsys+0x1f/0x50 > > > > > > Presumably the kworker/u16:6 completed, then modprobe hung? > > > > > > If not, I have some very hard questions about why net_mutex can be > > > held by two tasks concurrently, given that it does not appear to be a > > > reader-writer lock... > > > > > > Either way, my patch assumed that 39953dfd4007 (rcu: Avoid misordering in > > > __call_rcu_nocb_enqueue()) would work and that 1772947bd012 (rcu: Handle > > > NOCB callbacks from irq-disabled idle code) would fail. Is that the case? > > > If not, could you please bisect the commits between 11ed7f934cb8 (rcu: > > > Make nocb leader kthreads process pending callbacks after spawning) > > > and c847f14217d5 (rcu: Avoid misordering in nocb_leader_wait())? > > > > Ok, unless I've messsed up something major, bisecting points to: > > > > 35ce7f29a44a rcu: Create rcuo kthreads only for onlined CPUs > > > > Makes any sense ? > > Good question. ;-) > > Are any of your online CPUs missing rcuo kthreads? There should be > kthreads named rcuos/0, rcuos/1, rcuos/2, and so on for each online CPU.
Its a Phenom II X6. With 3.17 and linux-tip with 35ce7f29a44a reverted, the rcuos are 8 and the modprobe ppp_generic testcase reliably works, libvirt also manages to setup its bridge.
Just with linux-tip , the rcuos are 6 but the failure is as reliable as before.
Awating instructions: :)
| |