Subject: [Bug 200055] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3214 .__lockdep_init_map+0x260/0x270

From: [email-masked]
Date: Sat, 27 Jul 2019 22:47:03 +0000

https://bugzilla.kernel.org/show_bug.cgi?id=200055

--- Comment #19 from Erhard F. ([email-masked]) ---
Created attachment 284001
  --> https://bugzilla.kernel.org/attachment.cgi?id=284001&action=edit
bisect.log

At last... I got the offending commit. Funnily enough it is about silencing
lockdep warnings. ;)

9e607f72748ddc5620aeeb8d1f32f30c79b360b9 is the first bad commit
commit 9e607f72748ddc5620aeeb8d1f32f30c79b360b9
Author: Denis Kirjanov <[email-masked]>
Date:   Wed Sep 21 14:34:58 2016 +0300

    i2c_powermac: shut up lockdep warning

    That's unclear why lockdep shows the following warning but adding a
    lockdep class to struct pmac_i2c_bus solves it

    [   20.507795] ======================================================
    [   20.507796] [ INFO: possible circular locking dependency detected ]
    [   20.507800] 4.8.0-rc7-00037-gd2ffb01 #21 Not tainted
    [   20.507801] -------------------------------------------------------
    [   20.507803] swapper/0/1 is trying to acquire lock:
    [   20.507818]  (&bus->mutex){+.+.+.}, at: [<c000000000052830>]
.pmac_i2c_open+0x30/0x100
    [   20.507819]
    [   20.507819] but task is already holding lock:
    [   20.507829]  (&policy->rwsem){+.+.+.}, at: [<c00000000068adcc>]
.cpufreq_online+0x1ac/0x9d0
    [   20.507830]
    [   20.507830] which lock already depends on the new lock.
    [   20.507830]
    [   20.507832]
    [   20.507832] the existing dependency chain (in reverse order) is:
    [   20.507837]
    [   20.507837] -> #4 (&policy->rwsem){+.+.+.}:
    [   20.507844]        [<c00000000082385c>] .down_write+0x6c/0x110
    [   20.507849]        [<c00000000068adcc>] .cpufreq_online+0x1ac/0x9d0
    [   20.507855]        [<c0000000004d76d8>]
.subsys_interface_register+0xb8/0x110
    [   20.507860]        [<c000000000689bb0>]
.cpufreq_register_driver+0x1d0/0x250
    [   20.507866]        [<c000000000b4f8f4>] .g5_cpufreq_init+0x9cc/0xa28
    [   20.507872]        [<c00000000000a98c>] .do_one_initcall+0x5c/0x1d0
    [   20.507878]        [<c000000000b0f86c>]
.kernel_init_freeable+0x1ac/0x28c
    [   20.507883]        [<c00000000000b3bc>] .kernel_init+0x1c/0x140
    [   20.507887]        [<c0000000000098f4>]
.ret_from_kernel_thread+0x58/0x64
    [   20.507894]
    [   20.507894] -> #3 (subsys mutex#2){+.+.+.}:
    [   20.507899]        [<c000000000820448>] .mutex_lock_nested+0xa8/0x590
    [   20.507903]        [<c0000000004d7f24>] .bus_probe_device+0x44/0xe0
    [   20.507907]        [<c0000000004d5208>] .device_add+0x508/0x730
    [   20.507911]        [<c0000000004dd528>] .register_cpu+0x118/0x190
    [   20.507916]        [<c000000000b14450>] .topology_init+0x148/0x248
    [   20.507921]        [<c00000000000a98c>] .do_one_initcall+0x5c/0x1d0
    [   20.507925]        [<c000000000b0f86c>]
.kernel_init_freeable+0x1ac/0x28c
    [   20.507929]        [<c00000000000b3bc>] .kernel_init+0x1c/0x140
    [   20.507934]        [<c0000000000098f4>]
.ret_from_kernel_thread+0x58/0x64
    [   20.507939]
    [   20.507939] -> #2 (cpu_add_remove_lock){+.+.+.}:
    [   20.507944]        [<c000000000820448>] .mutex_lock_nested+0xa8/0x590
    [   20.507950]        [<c000000000087a9c>] .register_cpu_notifier+0x2c/0x70
    [   20.507955]        [<c000000000b267e0>] .spawn_ksoftirqd+0x18/0x4c
    [   20.507959]        [<c00000000000a98c>] .do_one_initcall+0x5c/0x1d0
    [   20.507964]        [<c000000000b0f770>] .kernel_init_freeable+0xb0/0x28c
    [   20.507968]        [<c00000000000b3bc>] .kernel_init+0x1c/0x140
    [   20.507972]        [<c0000000000098f4>]
.ret_from_kernel_thread+0x58/0x64
    [   20.507978]
    [   20.507978] -> #1 (&host->mutex){+.+.+.}:
    [   20.507982]        [<c000000000820448>] .mutex_lock_nested+0xa8/0x590
    [   20.507987]        [<c0000000000527e8>] .kw_i2c_open+0x18/0x30
    [   20.507991]        [<c000000000052894>] .pmac_i2c_open+0x94/0x100
    [   20.507995]        [<c000000000b220a0>] .smp_core99_probe+0x260/0x410
    [   20.507999]        [<c000000000b185bc>] .smp_prepare_cpus+0x280/0x2ac
    [   20.508003]        [<c000000000b0f748>] .kernel_init_freeable+0x88/0x28c
    [   20.508008]        [<c00000000000b3bc>] .kernel_init+0x1c/0x140
    [   20.508012]        [<c0000000000098f4>]
.ret_from_kernel_thread+0x58/0x64
    [   20.508018]
    [   20.508018] -> #0 (&bus->mutex){+.+.+.}:
    [   20.508023]        [<c0000000000ed5b4>] .lock_acquire+0x84/0x100
    [   20.508027]        [<c000000000820448>] .mutex_lock_nested+0xa8/0x590
    [   20.508032]        [<c000000000052830>] .pmac_i2c_open+0x30/0x100
    [   20.508037]        [<c000000000052e14>] .pmac_i2c_do_begin+0x34/0x120
    [   20.508040]        [<c000000000056bc0>] .pmf_call_one+0x50/0xd0
    [   20.508045]        [<c00000000068ff1c>] .g5_pfunc_switch_volt+0x2c/0xc0
    [   20.508050]        [<c00000000068fecc>]
.g5_pfunc_switch_freq+0x1cc/0x1f0
    [   20.508054]        [<c00000000068fc2c>] .g5_cpufreq_target+0x2c/0x40
    [   20.508058]        [<c0000000006873ec>]
.__cpufreq_driver_target+0x23c/0x840
    [   20.508062]        [<c00000000068c798>]
.cpufreq_gov_performance_limits+0x18/0x30
    [   20.508067]        [<c00000000068915c>]
.cpufreq_start_governor+0xac/0x100
    [   20.508071]        [<c00000000068a788>] .cpufreq_set_policy+0x208/0x260
    [   20.508076]        [<c00000000068abdc>] .cpufreq_init_policy+0x6c/0xb0
    [   20.508081]        [<c00000000068ae70>] .cpufreq_online+0x250/0x9d0
    [   20.508085]        [<c0000000004d76d8>]
.subsys_interface_register+0xb8/0x110
    [   20.508090]        [<c000000000689bb0>]
.cpufreq_register_driver+0x1d0/0x250
    [   20.508094]        [<c000000000b4f8f4>] .g5_cpufreq_init+0x9cc/0xa28
    [   20.508099]        [<c00000000000a98c>] .do_one_initcall+0x5c/0x1d0
    [   20.508103]        [<c000000000b0f86c>]
.kernel_init_freeable+0x1ac/0x28c
    [   20.508107]        [<c00000000000b3bc>] .kernel_init+0x1c/0x140
    [   20.508112]        [<c0000000000098f4>]
.ret_from_kernel_thread+0x58/0x64
    [   20.508113]
    [   20.508113] other info that might help us debug this:
    [   20.508113]
    [   20.508121] Chain exists of:
    [   20.508121]   &bus->mutex --> subsys mutex#2 --> &policy->rwsem
    [   20.508121]
    [   20.508123]  Possible unsafe locking scenario:
    [   20.508123]
    [   20.508124]        CPU0                    CPU1
    [   20.508125]        ----                    ----
    [   20.508128]   lock(&policy->rwsem);
    [   20.508132]                                lock(subsys mutex#2);
    [   20.508135]                                lock(&policy->rwsem);
    [   20.508138]   lock(&bus->mutex);
    [   20.508139]
    [   20.508139]  *** DEADLOCK ***
    [   20.508139]
    [   20.508141] 3 locks held by swapper/0/1:
    [   20.508150]  #0:  (cpu_hotplug.lock){++++++}, at: [<c000000000087838>]
.get_online_cpus+0x48/0xc0
    [   20.508159]  #1:  (subsys mutex#2){+.+.+.}, at: [<c0000000004d7670>]
.subsys_interface_register+0x50/0x110
    [   20.508168]  #2:  (&policy->rwsem){+.+.+.}, at: [<c00000000068adcc>]
.cpufreq_online+0x1ac/0x9d0
    [   20.508169]
    [   20.508169] stack backtrace:
    [   20.508173] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
4.8.0-rc7-00037-gd2ffb01 #21
    [   20.508175] Call Trace:
    [   20.508180] [c0000000790c2b90] [c00000000082cc70] .dump_stack+0xe0/0x14c
(unreliable)
    [   20.508184] [c0000000790c2c20] [c000000000828c88]
.print_circular_bug+0x350/0x388
    [   20.508188] [c0000000790c2cd0] [c0000000000ecb0c]
.__lock_acquire+0x196c/0x1d30
    [   20.508192] [c0000000790c2e50] [c0000000000ed5b4]
.lock_acquire+0x84/0x100
    [   20.508196] [c0000000790c2f20] [c000000000820448]
.mutex_lock_nested+0xa8/0x590
    [   20.508201] [c0000000790c3030] [c000000000052830]
.pmac_i2c_open+0x30/0x100
    [   20.508206] [c0000000790c30c0] [c000000000052e14]
.pmac_i2c_do_begin+0x34/0x120
    [   20.508209] [c0000000790c3150] [c000000000056bc0]
.pmf_call_one+0x50/0xd0
    [   20.508213] [c0000000790c31e0] [c00000000068ff1c]
.g5_pfunc_switch_volt+0x2c/0xc0
    [   20.508217] [c0000000790c3250] [c00000000068fecc]
.g5_pfunc_switch_freq+0x1cc/0x1f0
    [   20.508221] [c0000000790c3320] [c00000000068fc2c]
.g5_cpufreq_target+0x2c/0x40
    [   20.508226] [c0000000790c3390] [c0000000006873ec]
.__cpufreq_driver_target+0x23c/0x840
    [   20.508230] [c0000000790c3440] [c00000000068c798]
.cpufreq_gov_performance_limits+0x18/0x30
    [   20.508235] [c0000000790c34b0] [c00000000068915c]
.cpufreq_start_governor+0xac/0x100
    [   20.508239] [c0000000790c3530] [c00000000068a788]
.cpufreq_set_policy+0x208/0x260
    [   20.508244] [c0000000790c35d0] [c00000000068abdc]
.cpufreq_init_policy+0x6c/0xb0
    [   20.508249] [c0000000790c3940] [c00000000068ae70]
.cpufreq_online+0x250/0x9d0
    [   20.508253] [c0000000790c3a30] [c0000000004d76d8]
.subsys_interface_register+0xb8/0x110
    [   20.508258] [c0000000790c3ad0] [c000000000689bb0]
.cpufreq_register_driver+0x1d0/0x250
    [   20.508262] [c0000000790c3b60] [c000000000b4f8f4]
.g5_cpufreq_init+0x9cc/0xa28
    [   20.508267] [c0000000790c3c20] [c00000000000a98c]
.do_one_initcall+0x5c/0x1d0
    [   20.508271] [c0000000790c3d00] [c000000000b0f86c]
.kernel_init_freeable+0x1ac/0x28c
    [   20.508276] [c0000000790c3db0] [c00000000000b3bc]
.kernel_init+0x1c/0x140
    [   20.508280] [c0000000790c3e30] [c0000000000098f4]
.ret_from_kernel_thread+0x58/0x64

    Signed-off-by: Denis Kirjanov <[email-masked]>
    Signed-off-by: Michael Ellerman <[email-masked]>

:040000 040000 18ec5f23dbd03c624aae71f3cbb05466dd38bf91
d4d7866e7cf3060e9ae1c76ad390194d4d789dcd M      arch

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