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From: Joel Fernandes <joel@joelfernandes.org>
To: Shuah Khan <shuah@kernel.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
Subject: Re: [RFC PATCH 0/2] improve vmalloc allocation
Date: Tue, 23 Oct 2018 12:30:44 -0700	[thread overview]
Message-ID: <20181023193044.GA139403@joelaf.mtv.corp.google.com> (raw)
In-Reply-To: <98842edb-d462-96b1-311f-27c6ebfc108a@kernel.org>

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.

How would you prevent that?

thanks,

 - Joel

  reply	other threads:[~2018-10-23 19:30 UTC|newest]

Thread overview: 28+ 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
2018-10-19 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 [this message]
2018-10-23 19:48                 ` Shuah Khan
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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