From: Shuah Khan <shuah@kernel.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: Michal Hocko <mhocko@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Uladzislau Rezki <urezki@gmail.com>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Thomas Garnier <thgarnie@google.com>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>,
Steven Rostedt <rostedt@goodmis.org>,
Joel Fernandes <joelaf@google.com>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
Tejun Heo <tj@kernel.org>,
maco@android.com, Shuah Khan <shuah@kernel.org>
Subject: Re: [RFC PATCH 0/2] improve vmalloc allocation
Date: Tue, 23 Oct 2018 13:48:32 -0600 [thread overview]
Message-ID: <024af44a-77e1-1c61-c9b2-64ffbe4f7c49@kernel.org> (raw)
In-Reply-To: <20181023193044.GA139403@joelaf.mtv.corp.google.com>
On 10/23/2018 01:30 PM, Joel Fernandes wrote:
> On Tue, Oct 23, 2018 at 11:13:36AM -0600, Shuah Khan wrote:
>> On 10/23/2018 11:05 AM, Michal Hocko wrote:
>>> On Tue 23-10-18 08:26:40, Matthew Wilcox wrote:
>>>> On Tue, Oct 23, 2018 at 09:02:56AM -0600, Shuah Khan wrote:
>>> [...]
>>>>> The way it can be handled is by adding a test module under lib. test_kmod,
>>>>> test_sysctl, test_user_copy etc.
>>>>
>>>> The problem is that said module can only invoke functions which are
>>>> exported using EXPORT_SYMBOL. And there's a cost to exporting them,
>>>> which I don't think we're willing to pay, purely to get test coverage.
>>>
>>> Yes, I think we do not want to export internal functionality which might
>>> be still interesting for the testing coverage. Maybe we want something
>>> like EXPORT_SYMBOL_KSELFTEST which would allow to link within the
>>> kselftest machinery but it wouldn't allow the same for general modules
>>> and will not give any API promisses.
>>>
>>
>> I like this proposal. I think we will open up lot of test opportunities with
>> this approach.
>>
>> Maybe we can use this stress test as a pilot and see where it takes us.
>
> I am a bit worried that such an EXPORT_SYMBOL_KSELFTEST mechanism can be abused by
> out-of-tree module writers to call internal functionality.
That is valid concern to consider before we go forward with the proposal.
We could wrap EXPORT_SYMBOL_KSELFTEST this in an existing debug option. This could
be fine grained for each sub-system for its debug option. We do have a few of these
now
# CONFIG_STATIC_KEYS_SELFTEST is not set
# CONFIG_BT_SELFTEST is not set
# CONFIG_DRM_DEBUG_SELFTEST is not set
# CONFIG_CHASH_SELFTEST is not set
# CONFIG_DRM_I915_SELFTEST is not set
# CONFIG_CRC32_SELFTEST is not set
# CONFIG_RANDOM32_SELFTEST is not set
# CONFIG_GLOB_SELFTEST is not set
# CONFIG_STRING_SELFTEST is not set
# CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set
# CONFIG_WW_MUTEX_SELFTEST is not set
# CONFIG_ATOMIC64_SELFTEST is not set
# CONFIG_X86_DECODER_SELFTEST is not set
# CONFIG_DEBUG_NMI_SELFTEST is not set
thanks,
-- Shuah
next prev parent reply other threads:[~2018-10-23 19:48 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-19 17:35 [RFC PATCH 0/2] improve vmalloc allocation Uladzislau Rezki (Sony)
2018-10-19 17:35 ` [RFC PATCH 1/2] mm/vmalloc: keep track of free blocks for allocation Uladzislau Rezki (Sony)
2018-10-29 13:39 ` [LKP] [mm/vmalloc] 8dab1f5c1e: BUG:soft_lockup-CPU##stuck_for#s kernel test robot
2018-10-29 13:39 ` kernel test robot
2018-10-29 13:39 ` [LKP] " kernel test robot
2018-10-19 17:35 ` [RFC PATCH 2/2] mm: add priority threshold to __purge_vmap_area_lazy() Uladzislau Rezki (Sony)
2018-10-19 22:44 ` [RFC PATCH 0/2] improve vmalloc allocation Roman Gushchin
2018-10-22 14:01 ` Uladzislau Rezki
2018-10-20 0:11 ` Joel Fernandes
2018-10-22 14:50 ` Uladzislau Rezki
2018-10-23 6:36 ` Joel Fernandes
2018-10-22 12:51 ` Michal Hocko
2018-10-22 16:52 ` Uladzislau Rezki
2018-10-23 7:23 ` Michal Hocko
2018-10-23 15:02 ` Shuah Khan
2018-10-23 15:26 ` Matthew Wilcox
2018-10-23 17:05 ` Michal Hocko
2018-10-23 17:13 ` Shuah Khan
2018-10-23 19:30 ` Joel Fernandes
2018-10-23 19:48 ` Shuah Khan [this message]
2018-10-23 20:09 ` Matthew Wilcox
2018-10-23 20:50 ` Shuah Khan
2018-10-23 21:01 ` Joel Fernandes
2018-10-24 6:22 ` Michal Hocko
2018-10-24 17:34 ` Uladzislau Rezki
2018-10-25 8:43 ` Michal Hocko
2018-10-25 10:42 ` Uladzislau Rezki
2018-10-24 16:36 ` Uladzislau Rezki
2018-10-24 23:01 ` Andrew Morton
2018-10-25 10:33 ` Uladzislau Rezki
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