From: Randy Dunlap <rdunlap@infradead.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: linux-kernel@vger.kernel.org,
Naresh Kamboju <naresh.kamboju@linaro.org>,
kernel test robot <rong.a.chen@intel.com>,
Brendan Higgins <brendanhiggins@google.com>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH] kobject: Make sure the parent does not get released before its children
Date: Sat, 23 May 2020 08:44:06 -0700 [thread overview]
Message-ID: <7a5e4740-8099-ef70-776f-0d92ce84ab3d@infradead.org> (raw)
In-Reply-To: <20200523153643.GA226270@kroah.com>
On 5/23/20 8:36 AM, Greg Kroah-Hartman wrote:
> On Wed, May 13, 2020 at 06:18:40PM +0300, Heikki Krogerus wrote:
>> In the function kobject_cleanup(), kobject_del(kobj) is
>> called before the kobj->release(). That makes it possible to
>> release the parent of the kobject before the kobject itself.
>>
>> To fix that, adding function __kboject_del() that does
>> everything that kobject_del() does except release the parent
>> reference. kobject_cleanup() then calls __kobject_del()
>> instead of kobject_del(), and separately decrements the
>> reference count of the parent kobject after kobj->release()
>> has been called.
>>
>> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
>> Reported-by: kernel test robot <rong.a.chen@intel.com>
>> Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function"")
>> Suggested-by: "Rafael J. Wysocki" <rafael@kernel.org>
>> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
>> Tested-by: Brendan Higgins <brendanhiggins@google.com>
>> Acked-by: Randy Dunlap <rdunlap@infradead.org>
>> ---
>> lib/kobject.c | 30 ++++++++++++++++++++----------
>> 1 file changed, 20 insertions(+), 10 deletions(-)
>
> Stepping back, now that it turns out this patch causes more problems
> than it fixes, how is everyone reproducing the original crash here?
Just load lib/test_printf.ko and boom!
> Is it just the KUNIT_DRIVER_PE_TEST that is causing the issue?
>
> In looking at 7589238a8cf3 ("Revert "software node: Simplify
> software_node_release() function""), the log messages there look
> correct. sysfs can't create a duplicate file, and so when your test is
> written to try to create software nodes, you always have to check the
> return value. If you run the test in parallel, or before another test
> has had a chance to clean up, the function will fail, correctly.
>
> So what real-world thing is this test "failure" trying to show?
--
~Randy
next prev parent reply other threads:[~2020-05-23 15:44 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 15:18 [PATCH] kobject: Make sure the parent does not get released before its children Heikki Krogerus
2020-05-13 15:20 ` Rafael J. Wysocki
2020-05-13 15:42 ` Greg Kroah-Hartman
2020-05-13 15:51 ` Rafael J. Wysocki
2020-05-13 20:18 ` Brendan Higgins
2020-05-13 20:54 ` Randy Dunlap
2020-05-13 21:30 ` Brendan Higgins
2020-05-13 23:14 ` Randy Dunlap
2020-05-14 6:54 ` Heikki Krogerus
2020-05-15 15:10 ` Greg Kroah-Hartman
2020-05-23 13:21 ` Guenter Roeck
2020-05-23 13:29 ` Guenter Roeck
2020-05-23 14:04 ` Greg Kroah-Hartman
2020-05-23 15:36 ` Greg Kroah-Hartman
2020-05-23 15:44 ` Randy Dunlap [this message]
2020-05-23 19:04 ` Dmitry Torokhov
2020-05-24 11:42 ` Greg Kroah-Hartman
2020-05-24 12:57 ` Greg Kroah-Hartman
2020-05-24 13:14 ` Greg Kroah-Hartman
2020-05-24 13:28 ` Greg Kroah-Hartman
2020-05-24 15:35 ` Greg Kroah-Hartman
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