On Wed, Oct 27, 2021 at 6:06 AM Sebastian Andrzej Siewior
<bigeasy@xxxxxxxxxxxxx> wrote:
>
> On 2021-10-18 12:51:32 [-0300], Luis Goncalves wrote:
> > Again, the use of tuned in the tests is mostly to reproduce the
> > configuration in use at
> > the moment. I can isolate the specific configuration that makes it
> > possible to trigger the
> > lockdep splat.
>
> I can't reproduce any of those two issues. I tried both and iterated the
> tuned profiles
> tuned-adm profile realtime
> tuned-adm profile throughput-performance
>
> while running the test you mentioned.
> Could you please try if this reproduces with latest v5.15-RT and post
> complete lockdep backtrace?
I couldn't reproduce that on v5.14-rt nor v5.15-rt. But I can easily
reproduce the lockdep splat on v5.10-rt, though.
This is the backtrace for v5.10.73-rt54:
[ 220.768268] run.sh (2905): /proc/2142/oom_adj is deprecated, please
use /proc/2142/oom_score_adj instead.
[ 221.794958] LTP: starting read_all_proc (read_all -d /proc -q -r 3)
[ 222.678607] ICMPv6: process `read_all' is using deprecated sysctl
(syscall) net.ipv6.neigh.default.base_reachable_time - use
net.ipv6.neigh.default.base_reachable_time_ms instead
[ 222.897071] ======================================================
[ 222.897071] WARNING: possible circular locking dependency detected
[ 222.897072] 5.10.73-rt54.lockdep+ #2 Tainted: G S W I
[ 222.897073] ------------------------------------------------------
[ 222.897074] read_all/3946 is trying to acquire lock:
[ 222.897075] ffff9727dee18220
((softirq_ctrl.lock).lock){+.+.}-{2:2}, at:
__local_bh_disable_ip+0x116/0x2f0
[ 222.897084]
but task is already holding lock:
[ 222.897085] ffffffffba2e9720 (raw_v6_hashinfo.lock){++.+}-{0:0},
at: raw_seq_start+0x25/0x60
[ 222.897090]
which lock already depends on the new lock.
[ 222.897091]
the existing dependency chain (in reverse order) is:
[ 222.897092]
-> #1 (raw_v6_hashinfo.lock){++.+}-{0:0}:
[ 222.897093] lock_acquire+0xde/0x380
[ 222.897098] rt_write_lock+0x3a/0x1b0
[ 222.897101] raw_hash_sk+0x3f/0xd0
[ 222.897103] inet6_create+0x2ef/0x690
[ 222.897107] __sock_create+0x1e2/0x430
[ 222.897111] inet_ctl_sock_create+0x33/0x90
[ 222.897113] icmpv6_sk_init+0x71/0x130
[ 222.897118] ops_init+0x3a/0x180
[ 222.897123] register_pernet_operations+0x126/0x220
[ 222.897125] register_pernet_subsys+0x24/0x40
[ 222.897127] icmpv6_init+0x11/0x4c
[ 222.897132] inet6_init+0x112/0x373
[ 222.897133] do_one_initcall+0x74/0x440
[ 222.897137] kernel_init_freeable+0x39d/0x408
[ 222.897140] kernel_init+0xb/0x12e
[ 222.897142] ret_from_fork+0x1f/0x30
[ 222.897144]
-> #0 ((softirq_ctrl.lock).lock){+.+.}-{2:2}:
[ 222.897145] check_prevs_add+0x1bb/0xe50
[ 222.897147] __lock_acquire+0x1187/0x1640
[ 222.897149] lock_acquire+0xde/0x380
[ 222.897151] rt_spin_lock+0x2b/0xd0
[ 222.897152] __local_bh_disable_ip+0x116/0x2f0
[ 222.897155] sock_i_ino+0x22/0x60
[ 222.897157] __ip6_dgram_sock_seq_show+0x3e/0xe0
[ 222.897160] raw6_seq_show+0x28/0x40
[ 222.897162] seq_read_iter+0x27e/0x420
[ 222.897166] seq_read+0x10f/0x160
[ 222.897168] proc_reg_read+0x3e/0x80
[ 222.897171] vfs_read+0xe7/0x1e0
[ 222.897174] ksys_read+0x5f/0xe0
[ 222.897175] do_syscall_64+0x33/0x40
[ 222.897178] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 222.897179]
other info that might help us debug this:
[ 222.897179] Possible unsafe locking scenario:
[ 222.897180] CPU0 CPU1
[ 222.897180] ---- ----
[ 222.897180] lock(raw_v6_hashinfo.lock);
[ 222.897181] lock((softirq_ctrl.lock).lock);
[ 222.897182] lock(raw_v6_hashinfo.lock);
[ 222.897183] lock((softirq_ctrl.lock).lock);
[ 222.897183]
*** DEADLOCK ***
[ 222.897184] 3 locks held by read_all/3946:
[ 222.897185] #0: ffff9720939dfe10 (&p->lock){+.+.}-{0:0}, at:
seq_read_iter+0x56/0x420
[ 222.897188] #1: ffffffffba2e9720
(raw_v6_hashinfo.lock){++.+}-{0:0}, at: raw_seq_start+0x25/0x60
[ 222.897191] #2: ffffffffb9ec8fe0 (rcu_read_lock){....}-{1:2}, at:
rt_read_lock+0x7d/0x1e0
[ 222.897194]
stack backtrace:
[ 222.897195] CPU: 28 PID: 3946 Comm: read_all Tainted: G S W I
5.10.73-rt54.lockdep+ #2
[ 222.897196] Hardware name: Dell Inc. PowerEdge R740/07X9K0, BIOS
2.8.2 08/27/2020
[ 222.897197] Call Trace:
[ 222.897199] dump_stack+0x77/0x97
[ 222.897204] check_noncircular+0xff/0x120
[ 222.897208] check_prevs_add+0x1bb/0xe50
[ 222.897211] __lock_acquire+0x1187/0x1640
[ 222.897215] lock_acquire+0xde/0x380
[ 222.897217] ? __local_bh_disable_ip+0x116/0x2f0
[ 222.897221] ? sock_i_ino+0x5/0x60
[ 222.897223] rt_spin_lock+0x2b/0xd0
[ 222.897224] ? __local_bh_disable_ip+0x116/0x2f0
[ 222.897227] __local_bh_disable_ip+0x116/0x2f0
[ 222.897229] sock_i_ino+0x22/0x60
[ 222.897231] __ip6_dgram_sock_seq_show+0x3e/0xe0
[ 222.897234] raw6_seq_show+0x28/0x40
[ 222.897236] seq_read_iter+0x27e/0x420
[ 222.897239] seq_read+0x10f/0x160
[ 222.897243] proc_reg_read+0x3e/0x80
[ 222.897245] vfs_read+0xe7/0x1e0
[ 222.897247] ksys_read+0x5f/0xe0
[ 222.897249] do_syscall_64+0x33/0x40
[ 222.897251] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 222.897254] RIP: 0033:0x7f71817b99b2
[ 222.897256] Code: 96 20 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb
b6 0f 1f 80 00 00 00 00 f3 0f 1e fa 8b 05 96 da 20 00 85 c0 75 12 31
c0 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 41 54 49 89 d4 55
48 89
[ 222.897258] RSP: 002b:00007ffed3549878 EFLAGS: 00000246 ORIG_RAX:
0000000000000000
[ 222.897259] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f71817b99b2
[ 222.897261] RDX: 00000000000003ff RSI: 00007ffed3549d20 RDI: 0000000000000003
[ 222.897262] RBP: 00007f7181bec000 R08: 0000000000000020 R09: 0000000000000000
[ 222.897262] R10: 0000000000000000 R11: 0000000000000246 R12: 000000002cab66e1
[ 222.897263] R13: 00007ffed3549921 R14: 0000000000624730 R15: 0000000000000000
[ 232.965010] LTP: starting read_all_sys (read_all -d /sys -q -r 3)
[ 235.930281] rtc_cmos 00:00: Deprecated ABI, please use nvmem
[ 237.200250] WARNING! power/level is deprecated; use power/control instead
