Messages in this thread | | | Date | Wed, 26 Jan 2022 07:08:22 +0100 | From | Juergen Gross <> | Subject | Re: Possible reproduction of CSD locking issue |
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On 25.01.22 19:27, Corey Minyard wrote: > We have a customer that had been seeing CSD lock issues on a Centos 7 > kernel (unfortunately). I couldn't find anything or any kernel changes > that might fix it, so I was consdering it was the CSD locking issue you > have been chasing for a while.
Is this on bare metal or in a virtualized environment?
The bug I was hunting occurred when running under Xen, and in the end I found a scheduling problem in the Xen hypervisor.
> > So I backported the debug patches. And of course, they stopped seeing > the issue, at least as much, and they had trouble with the extra CPU > time the debug code took. But they just reproduced it. Here are the > logs: > > Jan 23 23:39:43 worker0 kernel: [285737.522743] csd: Detected non-responsive CSD lock (#1) on CPU#3, waiting 5000000042 ns for CPU#55 flush_tlb_func+0x0/0xb0(0xffff8e0b3e2afbe8). > Jan 23 23:39:43 worker0 kernel: [285737.522744] csd: CSD lock (#1) unresponsive. > Jan 23 23:39:43 worker0 kernel: [285737.522747] csd: cnt(0000000): 0000->0000 queue > Jan 23 23:39:43 worker0 kernel: [285737.522748] csd: cnt(0000001): ffff->0037 idle > Jan 23 23:39:43 worker0 kernel: [285737.522749] csd: cnt(63d8dd8): 0003->0037 ipi > Jan 23 23:39:43 worker0 kernel: [285737.522750] csd: cnt(63d8dd9): 0003->0037 ping > Jan 23 23:39:43 worker0 kernel: [285737.522750] csd: cnt(63d8dda): 0003->ffff pinged > Jan 23 23:39:43 worker0 kernel: [285737.522751] csd: cnt(63d8dea): 0035->0037 pinged > Jan 23 23:39:43 worker0 kernel: [285737.522752] csd: cnt(63d8deb): ffff->0037 gotipi > Jan 23 23:39:43 worker0 kernel: [285737.522752] csd: cnt(63d8dec): ffff->0037 handle > Jan 23 23:39:43 worker0 kernel: [285737.522753] csd: cnt(63d8ded): ffff->0037 dequeue (src CPU 0 == empty) > Jan 23 23:39:43 worker0 kernel: [285737.522754] csd: cnt(63d8dee): ffff->0037 hdlend (src CPU 0 == early) > Jan 23 23:39:43 worker0 kernel: [285737.522754] csd: cnt(63d8e1f): 0003->0037 queue > Jan 23 23:39:43 worker0 kernel: [285737.522755] csd: cnt(63d8e20): 0003->0037 ipi > Jan 23 23:39:43 worker0 kernel: [285737.522756] csd: cnt(63d8e21): 0003->0037 ping > Jan 23 23:39:43 worker0 kernel: [285737.522756] csd: cnt(63d8e22): 0003->0037 queue > Jan 23 23:39:43 worker0 kernel: [285737.522757] csd: cnt(63d8e23): 0003->0037 noipi > Jan 23 23:39:43 worker0 kernel: [285737.522757] csd: cnt now: 63fe4cd > Jan 23 23:39:43 worker0 kernel: [285737.522758] Task dump for CPU 55: > Jan 23 23:39:43 worker0 kernel: [285737.522761] kubelet R running task 0 277695 1 0x00080000 > Jan 23 23:39:43 worker0 kernel: [285737.522761] Call Trace: > Jan 23 23:39:43 worker0 kernel: [285737.522769] [<ffffffff84376b6a>] ? __schedule+0x46a/0x990 > Jan 23 23:39:43 worker0 kernel: [285737.522774] [<ffffffff83db6353>] ? context_tracking_user_enter+0x13/0x20 > Jan 23 23:39:43 worker0 kernel: [285737.522776] [<ffffffff843775b5>] ? schedule_user+0x45/0x50 > Jan 23 23:39:43 worker0 kernel: [285737.522779] [<ffffffff8437b518>] ? retint_careful+0x16/0x34 > Jan 23 23:39:43 worker0 kernel: [285737.522780] csd: Re-sending CSD lock (#1) IPI from CPU#03 to CPU#55 > Jan 23 23:39:43 worker0 kernel: [285737.522788] CPU: 3 PID: 54671 Comm: runc:[2:INIT] Kdump: loaded Tainted: G OE ------------ T 3.10.0-1062.12.1.rt56.1042.mvista.test.14.el7.x86_64 #1 > Jan 23 23:39:43 worker0 kernel: [285737.522789] Hardware name: Dell Inc. PowerEdge R740/0YWR7D, BIOS 2.9.4 11/06/2020 > Jan 23 23:39:43 worker0 kernel: [285737.522789] Call Trace: > Jan 23 23:39:43 worker0 kernel: [285737.522793] [<ffffffff843718ba>] dump_stack+0x19/0x1b > Jan 23 23:39:43 worker0 kernel: [285737.522798] [<ffffffff83d0bcd8>] __csd_lock_wait+0x1a8/0x2a0 > Jan 23 23:39:43 worker0 kernel: [285737.522800] [<ffffffff83c6d870>] ? leave_mm+0x120/0x120 > Jan 23 23:39:43 worker0 kernel: [285737.522802] [<ffffffff83d0bfa4>] smp_call_function_single+0xc4/0x1b0 > Jan 23 23:39:43 worker0 kernel: [285737.522804] [<ffffffff83c6d870>] ? leave_mm+0x120/0x120 > Jan 23 23:39:43 worker0 kernel: [285737.522809] [<ffffffff83e2684b>] ? page_counter_uncharge+0x3b/0x70 > Jan 23 23:39:43 worker0 kernel: [285737.522811] [<ffffffff83d0c614>] smp_call_function_many+0x344/0x380 > Jan 23 23:39:43 worker0 kernel: [285737.522813] [<ffffffff83c6d870>] ? leave_mm+0x120/0x120 > Jan 23 23:39:43 worker0 kernel: [285737.522816] [<ffffffff83c6da38>] native_flush_tlb_others+0xb8/0xc0 > Jan 23 23:39:43 worker0 kernel: [285737.522818] [<ffffffff83c6dc25>] flush_tlb_page+0x65/0xf0 > Jan 23 23:39:43 worker0 kernel: [285737.522821] [<ffffffff83dfdf98>] ptep_clear_flush+0x68/0xa0 > Jan 23 23:39:43 worker0 kernel: [285737.522825] [<ffffffff83de6806>] wp_page_copy.isra.83+0x3d6/0x650 > Jan 23 23:39:43 worker0 kernel: [285737.522828] [<ffffffff83de8cb4>] do_wp_page+0xb4/0x710 > Jan 23 23:39:43 worker0 kernel: [285737.522832] [<ffffffff83decbb4>] handle_mm_fault+0x884/0x1340 > Jan 23 23:39:43 worker0 kernel: [285737.522835] [<ffffffff83cd7799>] ? update_cfs_shares+0xa9/0xf0 > Jan 23 23:39:43 worker0 kernel: [285737.522839] [<ffffffff8437efc3>] __do_page_fault+0x213/0x5a0 > Jan 23 23:39:43 worker0 kernel: [285737.522841] [<ffffffff8437f385>] do_page_fault+0x35/0x90 > Jan 23 23:39:43 worker0 kernel: [285737.522842] [<ffffffff8437b728>] page_fault+0x28/0x30 > Jan 23 23:39:43 worker0 kernel: [285737.522845] csd: CSD lock (#1) got unstuck on CPU#03, CPU#55 released the lock. > > Hopefully this is the issue you are chasing and not something else. > I've been studying them to see what they mean, but I thought you might > be interested to get them asap.
As said before: I've solved my problem.
But I can share some more insight from my experience:
Don't be so sure that resending the IPI woke up the cpu again. It might have been the NMI for getting the target cpu's stacktrace which resulted in letting it run again. I missed this possibility in the beginning and this was the reason I dismissed the Xen scheduling issue too early.
Juergen [unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] | |