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Subject: Re: [RFC PATCH 0/2] improve vmalloc allocation
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From: Shuah Khan <shuah@kernel.org>
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Date: Tue, 23 Oct 2018 14:50:53 -0600
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To: Matthew Wilcox <willy@infradead.org>
Cc: Joel Fernandes <joel@joelfernandes.org>, Michal Hocko <mhocko@kernel.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>

On 10/23/2018 02:09 PM, Matthew Wilcox wrote:
> On Tue, Oct 23, 2018 at 01:48:32PM -0600, Shuah Khan wrote:
>> On 10/23/2018 01:30 PM, Joel Fernandes wrote:
>>> On Tue, Oct 23, 2018 at 11:13:36AM -0600, Shuah Khan wrote:
>>>> 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
> 
> This all seems far more complicated than my proposed solution.
> 

Not sure if it that complicated. But it is more involved. It dies have the
advantage of fitting in with the rest of the debug/test type framework we
already have.

The option you proposed sounds simpler, however it sounds a bit adhoc to me.

In any case I went looking for EXPORT_SYMBOL defines and found them in 

tools/include/asm/export.h
tools/include/linux/export.h
tools/virtio/linux/export.h

selftests/powerpc/copyloops/asm/export.h
selftests/powerpc/stringloops/asm/export.h

thanks,
-- Shuah