ltp or kvm triggerable lockdep alloc_pid() deadlock gripe

[Mike Galbraith <efault@gmx.de>]

[-- Attachment #1: Type: text/plain, Size: 5886 bytes --]

Greetings,

The gripe below is repeatable in two ways here, boot with nomodeset so
nouveau doesn't steal the lockdep show when I then fire up one of my
(oink) full distro VM's, or from an ltp directory ./runltp -f cpuset
with the attached subset of controllers file placed in ./runtest dir.

Method2 may lead to a real deal deadlock, I've got a crashdump of one,
stack traces of uninterruptible sleepers attached.

[  154.927302] ======================================================
[  154.927303] WARNING: possible circular locking dependency detected
[  154.927304] 5.9.1-rt18-rt #5 Tainted: G S          E
[  154.927305] ------------------------------------------------------
[  154.927306] cpuset_inherit_/4992 is trying to acquire lock:
[  154.927307] ffff9d334c5e64d8 (&s->seqcount){+.+.}-{0:0}, at: __slab_alloc.isra.87+0xad/0xc0
[  154.927317]
               but task is already holding lock:
[  154.927317] ffffffffac4052d0 (pidmap_lock){+.+.}-{2:2}, at: alloc_pid+0x1fb/0x510
[  154.927324]
               which lock already depends on the new lock.

[  154.927324]
               the existing dependency chain (in reverse order) is:
[  154.927325]
               -> #1 (pidmap_lock){+.+.}-{2:2}:
[  154.927328]        lock_acquire+0x92/0x410
[  154.927331]        rt_spin_lock+0x2b/0xc0
[  154.927335]        free_pid+0x27/0xc0
[  154.927338]        release_task+0x34a/0x640
[  154.927340]        do_exit+0x6e9/0xcf0
[  154.927342]        kthread+0x11c/0x190
[  154.927344]        ret_from_fork+0x1f/0x30
[  154.927347]
               -> #0 (&s->seqcount){+.+.}-{0:0}:
[  154.927350]        validate_chain+0x981/0x1250
[  154.927352]        __lock_acquire+0x86f/0xbd0
[  154.927354]        lock_acquire+0x92/0x410
[  154.927356]        ___slab_alloc+0x71b/0x820
[  154.927358]        __slab_alloc.isra.87+0xad/0xc0
[  154.927359]        kmem_cache_alloc+0x700/0x8c0
[  154.927361]        radix_tree_node_alloc.constprop.22+0xa2/0xf0
[  154.927365]        idr_get_free+0x207/0x2b0
[  154.927367]        idr_alloc_u32+0x54/0xa0
[  154.927369]        idr_alloc_cyclic+0x4f/0xa0
[  154.927370]        alloc_pid+0x22b/0x510
[  154.927372]        copy_process+0xeb5/0x1de0
[  154.927375]        _do_fork+0x52/0x750
[  154.927377]        __do_sys_clone+0x64/0x70
[  154.927379]        do_syscall_64+0x33/0x40
[  154.927382]        entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  154.927384]
               other info that might help us debug this:

[  154.927384]  Possible unsafe locking scenario:

[  154.927385]        CPU0                    CPU1
[  154.927386]        ----                    ----
[  154.927386]   lock(pidmap_lock);
[  154.927388]                                lock(&s->seqcount);
[  154.927389]                                lock(pidmap_lock);
[  154.927391]   lock(&s->seqcount);
[  154.927392]
                *** DEADLOCK ***

[  154.927393] 4 locks held by cpuset_inherit_/4992:
[  154.927394]  #0: ffff9d33decea5b0 ((lock).lock){+.+.}-{2:2}, at: __radix_tree_preload+0x52/0x3b0
[  154.927399]  #1: ffffffffac598fa0 (rcu_read_lock){....}-{1:2}, at: rt_spin_lock+0x5/0xc0
[  154.927405]  #2: ffffffffac4052d0 (pidmap_lock){+.+.}-{2:2}, at: alloc_pid+0x1fb/0x510
[  154.927409]  #3: ffffffffac598fa0 (rcu_read_lock){....}-{1:2}, at: rt_spin_lock+0x5/0xc0
[  154.927414]
               stack backtrace:
[  154.927416] CPU: 3 PID: 4992 Comm: cpuset_inherit_ Kdump: loaded Tainted: G S          E     5.9.1-rt18-rt #5
[  154.927418] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013
[  154.927419] Call Trace:
[  154.927422]  dump_stack+0x77/0x9b
[  154.927425]  check_noncircular+0x148/0x160
[  154.927432]  ? validate_chain+0x981/0x1250
[  154.927435]  validate_chain+0x981/0x1250
[  154.927441]  __lock_acquire+0x86f/0xbd0
[  154.927446]  lock_acquire+0x92/0x410
[  154.927449]  ? __slab_alloc.isra.87+0xad/0xc0
[  154.927452]  ? kmem_cache_alloc+0x648/0x8c0
[  154.927453]  ? lock_acquire+0x92/0x410
[  154.927458]  ___slab_alloc+0x71b/0x820
[  154.927460]  ? __slab_alloc.isra.87+0xad/0xc0
[  154.927463]  ? radix_tree_node_alloc.constprop.22+0xa2/0xf0
[  154.927468]  ? __slab_alloc.isra.87+0x83/0xc0
[  154.927472]  ? radix_tree_node_alloc.constprop.22+0xa2/0xf0
[  154.927474]  ? __slab_alloc.isra.87+0xad/0xc0
[  154.927476]  __slab_alloc.isra.87+0xad/0xc0
[  154.927480]  ? radix_tree_node_alloc.constprop.22+0xa2/0xf0
[  154.927482]  kmem_cache_alloc+0x700/0x8c0
[  154.927487]  radix_tree_node_alloc.constprop.22+0xa2/0xf0
[  154.927491]  idr_get_free+0x207/0x2b0
[  154.927495]  idr_alloc_u32+0x54/0xa0
[  154.927500]  idr_alloc_cyclic+0x4f/0xa0
[  154.927503]  alloc_pid+0x22b/0x510
[  154.927506]  ? copy_thread+0x88/0x200
[  154.927512]  copy_process+0xeb5/0x1de0
[  154.927520]  _do_fork+0x52/0x750
[  154.927523]  ? lock_acquire+0x92/0x410
[  154.927525]  ? __might_fault+0x3e/0x90
[  154.927530]  ? find_held_lock+0x2d/0x90
[  154.927535]  __do_sys_clone+0x64/0x70
[  154.927541]  do_syscall_64+0x33/0x40
[  154.927544]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  154.927546] RIP: 0033:0x7f0b357356e3
[  154.927548] Code: db 45 85 ed 0f 85 ad 01 00 00 64 4c 8b 04 25 10 00 00 00 31 d2 4d 8d 90 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 f1 00 00 00 85 c0 41 89 c4 0f 85 fe 00 00
[  154.927550] RSP: 002b:00007ffdfd6d15f0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
[  154.927552] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0b357356e3
[  154.927554] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
[  154.927555] RBP: 00007ffdfd6d1620 R08: 00007f0b36052b80 R09: 0000000000000072
[  154.927556] R10: 00007f0b36052e50 R11: 0000000000000246 R12: 0000000000000000
[  154.927557] R13: 0000000000000000 R14: 0000000000000000 R15: 00005614ef57ecf0

[-- Attachment #2: cpuset --]
[-- Type: text/plain, Size: 587 bytes --]

#DESCRIPTION:Resource Management testing

cpuset_base_ops	cpuset_base_ops_testset.sh
cpuset_inherit	cpuset_inherit_testset.sh
cpuset_exclusive	cpuset_exclusive_test.sh
cpuset_hierarchy	cpuset_hierarchy_test.sh
cpuset_syscall	cpuset_syscall_testset.sh
cpuset_sched_domains	cpuset_sched_domains_test.sh
cpuset_load_balance	cpuset_load_balance_test.sh
cpuset_hotplug	cpuset_hotplug_test.sh
cpuset_memory	cpuset_memory_testset.sh
cpuset_memory_pressure	cpuset_memory_pressure_testset.sh
cpuset_memory_spread	cpuset_memory_spread_testset.sh

cpuset_regression_test cpuset_regression_test.sh


[-- Attachment #3: deadlock-log --]
[-- Type: text/plain, Size: 14019 bytes --]

      1      0   2  ffffa09c87fd0000  UN   0.1  221032   9368  systemd
    627      1   0  ffffa09f733c0000  UN   0.0   68392   7004  systemd-udevd
   3322   3247   7  ffffa09f512051c0  UN   0.0  167624   2732  gpg-agent
   3841   3468   2  ffffa09f32250000  UN   0.1   19912   9828  bash
   4209   3468   2  ffffa09dd070d1c0  UN   0.1   19912   9796  bash
   4845   3335   3  ffffa09f2ffe1b40  UN   0.1  268172  24880  file.so
   4846   3335   5  ffffa09f2d418000  UN   0.1  268172  24880  file.so
   5657      1   3  ffffa09f222e3680  UN   1.5 2884604 260248  Thread (pooled)
   6716   5797   3  ffffa09f30da1b40  UN   0.0   14128   4168  cpuset_hotplug_
   6743      1   3  ffffa09f54151b40  UN   0.1  574864  18532  pool-/usr/lib/x
   6744      1   4  ffffa09f357f9b40  UN   0.0  489516   6096  pool-/usr/lib/x
PID: 1      TASK: ffffa09c87fd0000  CPU: 2   COMMAND: "systemd"
 #0 [ffffbfbb00033c50] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb00033cd8] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb00033ce8] __rt_mutex_slowlock+56 at ffffffffa59b3868
 #3 [ffffbfbb00033d30] rt_mutex_slowlock_locked+207 at ffffffffa59b3abf
 #4 [ffffbfbb00033d88] rt_mutex_slowlock.constprop.30+90 at ffffffffa59b3d3a
 #5 [ffffbfbb00033e00] proc_cgroup_show+74 at ffffffffa5184a7a
 #6 [ffffbfbb00033e48] proc_single_show+84 at ffffffffa53cd524
 #7 [ffffbfbb00033e80] seq_read+206 at ffffffffa534c30e
 #8 [ffffbfbb00033ed8] vfs_read+209 at ffffffffa531d281
 #9 [ffffbfbb00033f08] ksys_read+135 at ffffffffa531d637
#10 [ffffbfbb00033f40] do_syscall_64+51 at ffffffffa59a35c3
#11 [ffffbfbb00033f50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f1bb97dd1d8  RSP: 00007ffd5f424ac0  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 000055e3b1224cc0  RCX: 00007f1bb97dd1d8
    RDX: 0000000000000400  RSI: 000055e3b1224cc0  RDI: 0000000000000055
    RBP: 0000000000000400   R8: 0000000000000000   R9: 0000000000000000
    R10: 00007f1bbb1f9940  R11: 0000000000000246  R12: 00007f1bb9aa57a0
    R13: 00007f1bb9aa62e0  R14: 0000000000000000  R15: 000055e3b1377f20
    ORIG_RAX: 0000000000000000  CS: 0033  SS: 002b
PID: 627    TASK: ffffa09f733c0000  CPU: 0   COMMAND: "systemd-udevd"
 #0 [ffffbfbb00b6fc38] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb00b6fcc0] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb00b6fcc8] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb00b6fd28] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb00b6fd40] cgroup_can_fork+1321 at ffffffffa5185e69
 #5 [ffffbfbb00b6fd88] copy_process+4457 at ffffffffa508aab9
 #6 [ffffbfbb00b6fe30] _do_fork+82 at ffffffffa508b882
 #7 [ffffbfbb00b6fed0] __do_sys_clone+100 at ffffffffa508c054
 #8 [ffffbfbb00b6ff40] do_syscall_64+51 at ffffffffa59a35c3
 #9 [ffffbfbb00b6ff50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007fa6261286e3  RSP: 00007ffc0a16daf0  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 00007ffc0a16daf0  RCX: 00007fa6261286e3
    RDX: 0000000000000000  RSI: 0000000000000000  RDI: 0000000001200011
    RBP: 00007ffc0a16db40   R8: 00007fa6272cfd40   R9: 0000000000000001
    R10: 00007fa6272d0010  R11: 0000000000000246  R12: 0000000000000000
    R13: 0000000000000000  R14: 0000000000000000  R15: 0000557a3d4a9a10
    ORIG_RAX: 0000000000000038  CS: 0033  SS: 002b
PID: 3322   TASK: ffffa09f512051c0  CPU: 7   COMMAND: "gpg-agent"
 #0 [ffffbfbb00ef7c38] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb00ef7cc0] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb00ef7cc8] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb00ef7d28] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb00ef7d40] cgroup_can_fork+1321 at ffffffffa5185e69
 #5 [ffffbfbb00ef7d88] copy_process+4457 at ffffffffa508aab9
 #6 [ffffbfbb00ef7e30] _do_fork+82 at ffffffffa508b882
 #7 [ffffbfbb00ef7ed0] __do_sys_clone+100 at ffffffffa508c054
 #8 [ffffbfbb00ef7f40] do_syscall_64+51 at ffffffffa59a35c3
 #9 [ffffbfbb00ef7f50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f4355ee7fb1  RSP: 00007ffdf3130358  RFLAGS: 00000202
    RAX: ffffffffffffffda  RBX: 00007f4355be7700  RCX: 00007f4355ee7fb1
    RDX: 00007f4355be79d0  RSI: 00007f4355be6fb0  RDI: 00000000003d0f00
    RBP: 00007ffdf3130760   R8: 00007f4355be7700   R9: 00007f4355be7700
    R10: 00007f4355be79d0  R11: 0000000000000202  R12: 00007ffdf31303fe
    R13: 00007ffdf31303ff  R14: 000055667da0f9e0  R15: 00007ffdf3130760
    ORIG_RAX: 0000000000000038  CS: 0033  SS: 002b
PID: 3841   TASK: ffffa09f32250000  CPU: 2   COMMAND: "bash"
 #0 [ffffbfbb02d0fc38] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb02d0fcc0] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb02d0fcc8] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb02d0fd28] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb02d0fd40] cgroup_can_fork+1321 at ffffffffa5185e69
 #5 [ffffbfbb02d0fd88] copy_process+4457 at ffffffffa508aab9
 #6 [ffffbfbb02d0fe30] _do_fork+82 at ffffffffa508b882
 #7 [ffffbfbb02d0fed0] __do_sys_clone+100 at ffffffffa508c054
 #8 [ffffbfbb02d0ff40] do_syscall_64+51 at ffffffffa59a35c3
 #9 [ffffbfbb02d0ff50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f023eaf36e3  RSP: 00007ffe80698a30  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000000  RCX: 00007f023eaf36e3
    RDX: 0000000000000000  RSI: 0000000000000000  RDI: 0000000001200011
    RBP: 00007ffe80698a60   R8: 00007f023f410b80   R9: 0000000000000000
    R10: 00007f023f410e50  R11: 0000000000000246  R12: 0000000000000000
    R13: 0000000000000000  R14: 0000562cd4ee6c90  R15: 0000562cd4ee6c90
    ORIG_RAX: 0000000000000038  CS: 0033  SS: 002b
PID: 4209   TASK: ffffa09dd070d1c0  CPU: 2   COMMAND: "bash"
 #0 [ffffbfbb0376fc38] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb0376fcc0] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb0376fcc8] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb0376fd28] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb0376fd40] cgroup_can_fork+1321 at ffffffffa5185e69
 #5 [ffffbfbb0376fd88] copy_process+4457 at ffffffffa508aab9
 #6 [ffffbfbb0376fe30] _do_fork+82 at ffffffffa508b882
 #7 [ffffbfbb0376fed0] __do_sys_clone+100 at ffffffffa508c054
 #8 [ffffbfbb0376ff40] do_syscall_64+51 at ffffffffa59a35c3
 #9 [ffffbfbb0376ff50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f81a96426e3  RSP: 00007ffd97e5ebc0  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000000  RCX: 00007f81a96426e3
    RDX: 0000000000000000  RSI: 0000000000000000  RDI: 0000000001200011
    RBP: 00007ffd97e5ebf0   R8: 00007f81a9f5fb80   R9: 0000000000000000
    R10: 00007f81a9f5fe50  R11: 0000000000000246  R12: 0000000000000000
    R13: 0000000000000000  R14: 000055a56fcb9c90  R15: 000055a56fcb9c90
    ORIG_RAX: 0000000000000038  CS: 0033  SS: 002b
PID: 4845   TASK: ffffa09f2ffe1b40  CPU: 3   COMMAND: "file.so"
 #0 [ffffbfbb03223d88] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb03223e10] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb03223e18] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb03223e78] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb03223e90] exit_signals+711 at ffffffffa50a2f27
 #5 [ffffbfbb03223ea8] do_exit+216 at ffffffffa5093ef8
 #6 [ffffbfbb03223f10] do_group_exit+71 at ffffffffa5094bb7
 #7 [ffffbfbb03223f38] __x64_sys_exit_group+20 at ffffffffa5094c34
 #8 [ffffbfbb03223f40] do_syscall_64+51 at ffffffffa59a35c3
 #9 [ffffbfbb03223f50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f0ca6b20998  RSP: 00007ffc5e1eef48  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000000  RCX: 00007f0ca6b20998
    RDX: 0000000000000000  RSI: 000000000000003c  RDI: 0000000000000000
    RBP: 00007f0ca6e0d510   R8: 00000000000000e7   R9: ffffffffffffff60
    R10: 00007f0ca5fd10f8  R11: 0000000000000246  R12: 00007f0ca6e0d510
    R13: 00007f0ca6e0d8c0  R14: 00007ffc5e1eefe0  R15: 0000000000000020
    ORIG_RAX: 00000000000000e7  CS: 0033  SS: 002b
PID: 4846   TASK: ffffa09f2d418000  CPU: 5   COMMAND: "file.so"
 #0 [ffffbfbb0396fd88] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb0396fe10] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb0396fe18] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb0396fe78] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb0396fe90] exit_signals+711 at ffffffffa50a2f27
 #5 [ffffbfbb0396fea8] do_exit+216 at ffffffffa5093ef8
 #6 [ffffbfbb0396ff10] do_group_exit+71 at ffffffffa5094bb7
 #7 [ffffbfbb0396ff38] __x64_sys_exit_group+20 at ffffffffa5094c34
 #8 [ffffbfbb0396ff40] do_syscall_64+51 at ffffffffa59a35c3
 #9 [ffffbfbb0396ff50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f0ca6b20998  RSP: 00007ffc5e1eef48  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000000  RCX: 00007f0ca6b20998
    RDX: 0000000000000000  RSI: 000000000000003c  RDI: 0000000000000000
    RBP: 00007f0ca6e0d510   R8: 00000000000000e7   R9: ffffffffffffff60
    R10: 00007f0ca5fd10f8  R11: 0000000000000246  R12: 00007f0ca6e0d510
    R13: 00007f0ca6e0d8c0  R14: 00007ffc5e1eefe0  R15: 0000000000000020
    ORIG_RAX: 00000000000000e7  CS: 0033  SS: 002b
PID: 5657   TASK: ffffa09f222e3680  CPU: 3   COMMAND: "Thread (pooled)"
 #0 [ffffbfbb03a07db0] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb03a07e38] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb03a07e40] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb03a07ea0] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb03a07eb8] exit_signals+711 at ffffffffa50a2f27
 #5 [ffffbfbb03a07ed0] do_exit+216 at ffffffffa5093ef8
 #6 [ffffbfbb03a07f38] __x64_sys_exit+23 at ffffffffa5094b67
 #7 [ffffbfbb03a07f40] do_syscall_64+51 at ffffffffa59a35c3
 #8 [ffffbfbb03a07f50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f1f2f9265b6  RSP: 00007f1e95057d50  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 00007f1e95058700  RCX: 00007f1f2f9265b6
    RDX: 000000000000003c  RSI: 00007f1f2fb38010  RDI: 0000000000000000
    RBP: 0000000000000000   R8: 00007f1e880029c0   R9: 0000000000000000
    R10: 0000000000000020  R11: 0000000000000246  R12: 00007ffd7582f27e
    R13: 00007ffd7582f27f  R14: 000055fce0818180  R15: 00007ffd7582f350
    ORIG_RAX: 000000000000003c  CS: 0033  SS: 002b
PID: 6716   TASK: ffffa09f30da1b40  CPU: 3   COMMAND: "cpuset_hotplug_"
 #0 [ffffbfbb03ac79d8] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb03ac7a60] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb03ac7a70] schedule_timeout+495 at ffffffffa59b4cbf
 #3 [ffffbfbb03ac7b08] wait_for_completion+165 at ffffffffa59b2f25
 #4 [ffffbfbb03ac7b48] affine_move_task+705 at ffffffffa50cc231
 #5 [ffffbfbb03ac7c88] __set_cpus_allowed_ptr+274 at ffffffffa50cc562
 #6 [ffffbfbb03ac7cc8] cpuset_attach+195 at ffffffffa518df73
 #7 [ffffbfbb03ac7d00] cgroup_migrate_execute+1133 at ffffffffa518075d
 #8 [ffffbfbb03ac7d58] cgroup_attach_task+524 at ffffffffa5180abc
 #9 [ffffbfbb03ac7e28] __cgroup1_procs_write.constprop.21+243 at ffffffffa5187843
#10 [ffffbfbb03ac7e68] cgroup_file_write+126 at ffffffffa517b07e
#11 [ffffbfbb03ac7ea0] kernfs_fop_write+275 at ffffffffa53e1c13
#12 [ffffbfbb03ac7ed8] vfs_write+240 at ffffffffa531d470
#13 [ffffbfbb03ac7f08] ksys_write+135 at ffffffffa531d737
#14 [ffffbfbb03ac7f40] do_syscall_64+51 at ffffffffa59a35c3
#15 [ffffbfbb03ac7f50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f0176b84244  RSP: 00007ffffcf7e2b8  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000005  RCX: 00007f0176b84244
    RDX: 0000000000000005  RSI: 000055b15203d890  RDI: 0000000000000001
    RBP: 000055b15203d890   R8: 000000000000000a   R9: 0000000000000000
    R10: 000000000000000a  R11: 0000000000000246  R12: 0000000000000005
    R13: 0000000000000001  R14: 00007f0176e4c5a0  R15: 0000000000000005
    ORIG_RAX: 0000000000000001  CS: 0033  SS: 002b
PID: 6743   TASK: ffffa09f54151b40  CPU: 3   COMMAND: "pool-/usr/lib/x"
 #0 [ffffbfbb08657db0] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb08657e38] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb08657e40] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb08657ea0] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb08657eb8] exit_signals+711 at ffffffffa50a2f27
 #5 [ffffbfbb08657ed0] do_exit+216 at ffffffffa5093ef8
 #6 [ffffbfbb08657f38] __x64_sys_exit+23 at ffffffffa5094b67
 #7 [ffffbfbb08657f40] do_syscall_64+51 at ffffffffa59a35c3
 #8 [ffffbfbb08657f50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007f0176d6b5b6  RSP: 00007f015d540dd0  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 00007f015d541700  RCX: 00007f0176d6b5b6
    RDX: 000000000000003c  RSI: 00007f0176f7d010  RDI: 0000000000000000
    RBP: 0000000000000000   R8: 00007f01500008c0   R9: 0000000000000004
    R10: 000055ee65f185d0  R11: 0000000000000246  R12: 00007ffc71eef56e
    R13: 00007ffc71eef56f  R14: 00007f01640038f0  R15: 00007ffc71eef600
    ORIG_RAX: 000000000000003c  CS: 0033  SS: 002b
PID: 6744   TASK: ffffa09f357f9b40  CPU: 4   COMMAND: "pool-/usr/lib/x"
 #0 [ffffbfbb0865fdb0] __schedule+837 at ffffffffa59b15f5
 #1 [ffffbfbb0865fe38] schedule+86 at ffffffffa59b1d96
 #2 [ffffbfbb0865fe40] percpu_rwsem_wait+181 at ffffffffa5101b75
 #3 [ffffbfbb0865fea0] __percpu_down_read+114 at ffffffffa5101ec2
 #4 [ffffbfbb0865feb8] exit_signals+711 at ffffffffa50a2f27
 #5 [ffffbfbb0865fed0] do_exit+216 at ffffffffa5093ef8
 #6 [ffffbfbb0865ff38] __x64_sys_exit+23 at ffffffffa5094b67
 #7 [ffffbfbb0865ff40] do_syscall_64+51 at ffffffffa59a35c3
 #8 [ffffbfbb0865ff50] entry_SYSCALL_64_after_hwframe+68 at ffffffffa5a0008c
    RIP: 00007ff49b0c85b6  RSP: 00007ff493ffedd0  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 00007ff493fff700  RCX: 00007ff49b0c85b6
    RDX: 000000000000003c  RSI: 00007ff49b2da010  RDI: 0000000000000000
    RBP: 0000000000000000   R8: 00007ff488001600   R9: 0000000000000000
    R10: 0000000000000050  R11: 0000000000000246  R12: 00007ffdc88c817e
    R13: 00007ffdc88c817f  R14: 00007ff48c0069e0  R15: 00007ffdc88c8210
    ORIG_RAX: 000000000000003c  CS: 0033  SS: 002b