Date:   Wed, 15 Jul 2020 10:22:34 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Saravana Kannan <saravanak@...gle.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v3 0/3] driver core: Add device link related sysfs files

Hi Greg and Saravana,

On 10.07.2020 15:23, Greg Kroah-Hartman wrote:
> On Mon, Jul 06, 2020 at 03:45:02PM -0700, Saravana Kannan wrote:
>> On Tue, Jun 16, 2020 at 8:45 PM Saravana Kannan <saravanak@...gle.com> wrote:
>>> On Fri, May 29, 2020 at 5:30 AM Greg Kroah-Hartman
>>> <gregkh@...uxfoundation.org> wrote:
>>>> Looks semi-sane, but it's too close to the merge window at the moment
>>>> for me to take this.  If there's no objections by the time 5.8-rc1 is
>>>> out, I'll queue it up in my tree for 5.9-rc1.
>>> Another friendly reminder :)
>> *nudge* *nudge*
> Looks sane, given no objections, let's see what linux-next thinks about
> it...

linux-next is not very happy from this patchset... Starting from 
next-20200713 I see a few new issues on various Samsung Exynos based 
boards. Here are examples from Exynos4412-based Odroid U3 board (ARM 
32bit, kernel compiled from exynos_defconfig):

BUG: sleeping function called from invalid context at 
kernel/locking/mutex.c:935
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 12, name: kworker/0:1
2 locks held by kworker/0:1/12:
  #0: ee8074a8 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: 
process_one_work+0x174/0x7dc
  #1: ee921f20 ((work_completion)(&sdp->work)){+.+.}-{0:0}, at: 
process_one_work+0x174/0x7dc
Preemption disabled at:
[<c01b10f0>] srcu_invoke_callbacks+0xc0/0x154
CPU: 0 PID: 12 Comm: kworker/0:1 Tainted: G        W 
5.8.0-rc3-00022-g287905e68dd2 #8753
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: rcu_gp srcu_invoke_callbacks
[<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
[<c010d250>] (show_stack) from [<c0517f04>] (dump_stack+0xbc/0xe8)
[<c0517f04>] (dump_stack) from [<c0159188>] (___might_sleep+0x288/0x2d8)
[<c0159188>] (___might_sleep) from [<c0abbd1c>] (__mutex_lock+0x48/0xb18)
[<c0abbd1c>] (__mutex_lock) from [<c0abc808>] (mutex_lock_nested+0x1c/0x24)
[<c0abc808>] (mutex_lock_nested) from [<c064590c>] (device_del+0x30/0x39c)
[<c064590c>] (device_del) from [<c0645c9c>] (device_unregister+0x24/0x64)
[<c0645c9c>] (device_unregister) from [<c01b10fc>] 
(srcu_invoke_callbacks+0xcc/0x154)
[<c01b10fc>] (srcu_invoke_callbacks) from [<c01493c4>] 
(process_one_work+0x234/0x7dc)
[<c01493c4>] (process_one_work) from [<c01499b0>] (worker_thread+0x44/0x51c)
[<c01499b0>] (worker_thread) from [<c0150bf4>] (kthread+0x158/0x1a0)
[<c0150bf4>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xee921fb0 to 0xee921ff8)


BUG: scheduling while atomic: kworker/0:0/5/0x00000201
3 locks held by kworker/0:0/5:
  #0: ee8074a8 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: 
process_one_work+0x174/0x7dc
  #1: ee907f20 ((work_completion)(&sdp->work)){+.+.}-{0:0}, at: 
process_one_work+0x174/0x7dc
  #2: c11367e4 (kernfs_mutex){+.+.}-{3:3}, at: 
kernfs_remove_by_name_ns+0x24/0x94
Modules linked in:
Preemption disabled at:
[<c01b10f0>] srcu_invoke_callbacks+0xc0/0x154
CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G        W 
5.8.0-rc3-00022-g287905e68dd2 #8753
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: rcu_gp srcu_invoke_callbacks
[<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
[<c010d250>] (show_stack) from [<c0517f04>] (dump_stack+0xbc/0xe8)
[<c0517f04>] (dump_stack) from [<c0158da0>] (__schedule_bug+0x88/0xe0)
[<c0158da0>] (__schedule_bug) from [<c0ab7f88>] (__schedule+0x5d0/0x83c)
[<c0ab7f88>] (__schedule) from [<c0ab8258>] (schedule+0x64/0x124)
[<c0ab8258>] (schedule) from [<c0ab8768>] 
(schedule_preempt_disabled+0x14/0x20)
[<c0ab8768>] (schedule_preempt_disabled) from [<c0abc1ec>] 
(__mutex_lock+0x518/0xb18)
[<c0abc1ec>] (__mutex_lock) from [<c0abc808>] (mutex_lock_nested+0x1c/0x24)
[<c0abc808>] (mutex_lock_nested) from [<c0362fc0>] 
(kernfs_remove_by_name_ns+0x24/0x94)
[<c0362fc0>] (kernfs_remove_by_name_ns) from [<c0644eac>] 
(device_remove_class_symlinks+0x70/0x94)
[<c0644eac>] (device_remove_class_symlinks) from [<c0645994>] 
(device_del+0xb8/0x39c)
[<c0645994>] (device_del) from [<c0645c9c>] (device_unregister+0x24/0x64)
[<c0645c9c>] (device_unregister) from [<c01b10fc>] 
(srcu_invoke_callbacks+0xcc/0x154)
[<c01b10fc>] (srcu_invoke_callbacks) from [<c01493c4>] 
(process_one_work+0x234/0x7dc)
[<c01493c4>] (process_one_work) from [<c01499b0>] (worker_thread+0x44/0x51c)
[<c01499b0>] (worker_thread) from [<c0150bf4>] (kthread+0x158/0x1a0)
[<c0150bf4>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xee907fb0 to 0xee907ff8)
sysfs: cannot create duplicate filename 
'/devices/virtual/devlink/regulator.28:cpu0'

------------[ cut here ]------------
WARNING: CPU: 0 PID: 5 at kernel/sched/core.c:3897 
preempt_count_sub+0x104/0x108
DEBUG_LOCKS_WARN_ON(val > preempt_count())
Modules linked in:
CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G        W 
5.8.0-rc3-00022-g287905e68dd2 #8753
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: rcu_gp srcu_invoke_callbacks
[<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
[<c010d250>] (show_stack) from [<c0517f04>] (dump_stack+0xbc/0xe8)
[<c0517f04>] (dump_stack) from [<c01270a8>] (__warn+0xf0/0x108)
[<c01270a8>] (__warn) from [<c0127134>] (warn_slowpath_fmt+0x74/0xb8)
[<c0127134>] (warn_slowpath_fmt) from [<c0158efc>] 
(preempt_count_sub+0x104/0x108)
[<c0158efc>] (preempt_count_sub) from [<c012fee4>] 
(__local_bh_enable_ip+0x74/0x16c)
[<c012fee4>] (__local_bh_enable_ip) from [<c01b1108>] 
(srcu_invoke_callbacks+0xd8/0x154)
[<c01b1108>] (srcu_invoke_callbacks) from [<c01493c4>] 
(process_one_work+0x234/0x7dc)
[<c01493c4>] (process_one_work) from [<c01499b0>] (worker_thread+0x44/0x51c)
[<c01499b0>] (worker_thread) from [<c0150bf4>] (kthread+0x158/0x1a0)
[<c0150bf4>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xee907fb0 to 0xee907ff8)
7fa0:                                     00000000 00000000 00000000 
00000000
7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
irq event stamp: 2274
hardirqs last  enabled at (2273): [<c02b3274>] __slab_free+0x2b0/0x480
hardirqs last disabled at (2274): [<c012fecc>] 
__local_bh_enable_ip+0x5c/0x16c
softirqs last  enabled at (2184): [<c010174c>] __do_softirq+0x50c/0x608
softirqs last disabled at (2056): [<c01b10e4>] 
srcu_invoke_callbacks+0xb4/0x154
---[ end trace eaa99e7b5e453175 ]---

PU: 0 PID: 1 Comm: swapper/0 Tainted: G        W 
5.8.0-rc3-00022-g287905e68dd2 #8753
Hardware name: Samsung Exynos (Flattened Device Tree)
[<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
[<c010d250>] (show_stack) from [<c0517f04>] (dump_stack+0xbc/0xe8)
[<c0517f04>] (dump_stack) from [<c0365474>] (sysfs_warn_dup+0x58/0x64)
[<c0365474>] (sysfs_warn_dup) from [<c03655a8>] 
(sysfs_create_dir_ns+0xe0/0xf4)
[<c03655a8>] (sysfs_create_dir_ns) from [<c051f218>] 
(kobject_add_internal+0xb8/0x370)
[<c051f218>] (kobject_add_internal) from [<c051f69c>] 
(kobject_add+0x5c/0xbc)
[<c051f69c>] (kobject_add) from [<c0647338>] (device_add+0x100/0x744)
[<c0647338>] (device_add) from [<c0647b88>] (device_link_add+0x1f4/0x5d0)
[<c0647b88>] (device_link_add) from [<c0582f60>] (_regulator_get+0xf4/0x280)
[<c0582f60>] (_regulator_get) from [<c0803da4>] 
(dev_pm_opp_set_regulators+0xf8/0x210)
[<c0803da4>] (dev_pm_opp_set_regulators) from [<c080df80>] 
(cpufreq_init+0xb8/0x304)
[<c080df80>] (cpufreq_init) from [<c080aae0>] (cpufreq_online+0x2c8/0x9f8)
[<c080aae0>] (cpufreq_online) from [<c080b2ac>] (cpufreq_add_dev+0x8c/0xc0)
[<c080b2ac>] (cpufreq_add_dev) from [<c0649854>] 
(subsys_interface_register+0xa8/0xf4)
[<c0649854>] (subsys_interface_register) from [<c0808184>] 
(cpufreq_register_driver+0x178/0x294)
[<c0808184>] (cpufreq_register_driver) from [<c080ddac>] 
(dt_cpufreq_probe+0xd8/0x1f4)
[<c080ddac>] (dt_cpufreq_probe) from [<c064e048>] 
(platform_drv_probe+0x6c/0xa4)
[<c064e048>] (platform_drv_probe) from [<c064b664>] 
(really_probe+0x200/0x48c)
[<c064b664>] (really_probe) from [<c064ba58>] 
(driver_probe_device+0x78/0x1fc)
[<c064ba58>] (driver_probe_device) from [<c064be40>] 
(device_driver_attach+0x58/0x60)
[<c064be40>] (device_driver_attach) from [<c064bf24>] 
(__driver_attach+0xdc/0x174)
[<c064bf24>] (__driver_attach) from [<c0649470>] 
(bus_for_each_dev+0x68/0xb4)
[<c0649470>] (bus_for_each_dev) from [<c064a7a4>] 
(bus_add_driver+0x158/0x214)
[<c064a7a4>] (bus_add_driver) from [<c064cdf8>] (driver_register+0x78/0x110)
[<c064cdf8>] (driver_register) from [<c0102378>] 
(do_one_initcall+0x8c/0x424)
[<c0102378>] (do_one_initcall) from [<c1001158>] 
(kernel_init_freeable+0x190/0x204)
[<c1001158>] (kernel_init_freeable) from [<c0ab7104>] 
(kernel_init+0x8/0x118)
[<c0ab7104>] (kernel_init) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xee8f1fb0 to 0xee8f1ff8)
...
BUG: sleeping function called from invalid context at 
kernel/locking/mutex.c:935
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5, name: kworker/0:0
INFO: lockdep is turned off.
Preemption disabled at:
[<c01b10f0>] srcu_invoke_callbacks+0xc0/0x154
CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G        W 
5.8.0-rc3-00022-g287905e68dd2 #8753
Hardware name: Samsung Exynos (Flattened Device Tree)
Workqueue: rcu_gp srcu_invoke_callbacks
[<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
[<c010d250>] (show_stack) from [<c0517f04>] (dump_stack+0xbc/0xe8)
[<c0517f04>] (dump_stack) from [<c0159188>] (___might_sleep+0x288/0x2d8)
[<c0159188>] (___might_sleep) from [<c0abbd1c>] (__mutex_lock+0x48/0xb18)
[<c0abbd1c>] (__mutex_lock) from [<c0abc808>] (mutex_lock_nested+0x1c/0x24)
[<c0abc808>] (mutex_lock_nested) from [<c064590c>] (device_del+0x30/0x39c)
[<c064590c>] (device_del) from [<c0645c9c>] (device_unregister+0x24/0x64)
[<c0645c9c>] (device_unregister) from [<c01b10fc>] 
(srcu_invoke_callbacks+0xcc/0x154)
[<c01b10fc>] (srcu_invoke_callbacks) from [<c01493c4>] 
(process_one_work+0x234/0x7dc)
[<c01493c4>] (process_one_work) from [<c01499b0>] (worker_thread+0x44/0x51c)
[<c01499b0>] (worker_thread) from [<c0150bf4>] (kthread+0x158/0x1a0)
[<c0150bf4>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xee907fb0 to 0xee907ff8)
...
kobject_add_internal failed for regulator.28:cpu0 with -EEXIST, don't 
try to register things with the same name in the same directory.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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