From: Linus Walleij <linus.walleij@linaro.org>
To: Naresh Kamboju <naresh.kamboju@linaro.org>,
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Anders Roxell <anders.roxell@linaro.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
lkft-triage@lists.linaro.org,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
Arnd Bergmann <arnd@arndb.de>, Shuah Khan <shuah@kernel.org>,
Bartosz Golaszewski <brgl@bgdev.pl>,
Andrew Morton <akpm@linux-foundation.org>,
Pengfei Xu <pengfei.xu@intel.com>,
yi1.lai@intel.com
Subject: Re: selftests: gpio: crash on arm64
Date: Tue, 11 Apr 2023 10:57:28 +0200 [thread overview]
Message-ID: <CACRpkdbUYWcFiRh+Y=MOekv2RjSP4sB2t5tVrSsz54Eez6wmVg@mail.gmail.com> (raw)
In-Reply-To: <CA+G9fYsOttth+k3Ki8LK_ZiayvXa0bAg-DmQAaFHZeEyR=6Lrw@mail.gmail.com>
On Mon, Apr 10, 2023 at 11:16 AM Naresh Kamboju
<naresh.kamboju@linaro.org> wrote:
(...)
> Anders performed bisection on this problem.
> The bisection have been poing to this commit log,
> first bad commit: [24c94060fc9b4e0f19e6e018869db46db21d6bc7]
> gpiolib: ensure that fwnode is properly set
I don't think this is the real issue.
(...)
> # 2. Module load error tests
> # 2.1 gpio overflow
(...)
> [ 88.900984] Freed in software_node_release+0xdc/0x108 age=34 cpu=1 pid=683
> [ 88.907899] __kmem_cache_free+0x2a4/0x2e0
> [ 88.912024] kfree+0xc0/0x1a0
> [ 88.915015] software_node_release+0xdc/0x108
> [ 88.919402] kobject_put+0xb0/0x220
> [ 88.922919] software_node_notify_remove+0x98/0xe8
> [ 88.927741] device_del+0x184/0x380
> [ 88.931259] platform_device_del.part.0+0x24/0xa8
> [ 88.935995] platform_device_unregister+0x30/0x50
I think the refcount is wrong on the fwnode.
The chip is allocated with devm_gpiochip_add_data() which will not call
gpiochip_remove() until all references are removed by calling
devm_gpio_chip_release().
Add a pr_info() devm_gpio_chip_release() in drivers/gpio/gpiolib-devres.c
and see if the callback is even called. I think this could be the
problem: if that isn't cleaned up, there will be dangling references.
diff --git a/drivers/gpio/gpiolib-devres.c b/drivers/gpio/gpiolib-devres.c
index fe9ce6b19f15..30a0622210d7 100644
--- a/drivers/gpio/gpiolib-devres.c
+++ b/drivers/gpio/gpiolib-devres.c
@@ -394,6 +394,7 @@ static void devm_gpio_chip_release(void *data)
{
struct gpio_chip *gc = data;
+ pr_info("GPIOCHIP %s WAS REMOVED BY DEVRES\n", gc->label);
gpiochip_remove(gc);
}
If this isn't working we need to figure out what is holding a reference to
the gpiochip.
I don't know how the references to the gpiochip fwnode is supposed to
drop to zero though? I didn't work with mockup much ...
What I could think of is that maybe the mockup driver need a .shutdown()
callback to forcibly call gpiochip_remove(), and in that case it should
be wrapped in a non-existining devm_gpiochip_remove() since devres
is used to register it.
Bartosz will know better though! I am pretty sure he has this working
flawlessly so the tests must be doing something weird which is leaving
references around.
Yours,
Linus Walleij
next prev parent reply other threads:[~2023-04-11 8:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-09 16:03 selftests: gpio: crash on arm64 Naresh Kamboju
2023-03-09 17:50 ` Andy Shevchenko
2023-04-10 9:16 ` Naresh Kamboju
2023-04-11 8:57 ` Linus Walleij [this message]
2023-04-11 13:11 ` Bartosz Golaszewski
2023-06-20 16:40 ` Andy Shevchenko
2023-11-07 13:51 ` Naresh Kamboju
2023-11-15 1:42 ` andy.shevchenko
2023-11-15 15:37 ` Naresh Kamboju
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