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SubjectRe: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options
>>>>> "Mikulas" == Mikulas Patocka <mpatocka@redhat.com> writes:

Mikulas> On Thu, 26 Apr 2018, John Stoffel wrote:

>> >>>>> "James" == James Bottomley <James.Bottomley@HansenPartnership.com> writes:
>>
James> I may be an atypical developer but I'd rather have a root canal
James> than browse through menuconfig options. The way to get people
James> to learn about new debugging options is to blog about it (or
James> write an lwn.net article) which google will find the next time
James> I ask it how I debug XXX. Google (probably as a service to
James> humanity) rarely turns up Kconfig options in response to a
James> query.
>>
>> I agree with James here. Looking at the SLAB vs SLUB Kconfig entries
>> tells me *nothing* about why I should pick one or the other, as an
>> example.
>>
>> John

Mikulas> I see your point - and I think the misunderstanding is this.

Thanks.

Mikulas> This patch is not really helping people to debug existing crashes. It is
Mikulas> not like "you get a crash" - "you google for some keywords" - "you get a
Mikulas> page that suggests to turn this option on" - "you turn it on and solve the
Mikulas> crash".

Mikulas> What this patch really does is that - it makes the kernel deliberately
Mikulas> crash in a situation when the code violates the specification, but it
Mikulas> would not crash otherwise or it would crash very rarely. It helps to
Mikulas> detect specification violations.

Mikulas> If the kernel developer (or tester) doesn't use this option, his buggy
Mikulas> code won't crash - and if it won't crash, he won't fix the bug or report
Mikulas> it. How is the user or developer supposed to learn about this option, if
Mikulas> he gets no crash at all?

So why do we make this a KConfig option at all? Just turn it on and
let it rip. Now I also think that Linus has the right idea to not
just sprinkle BUG_ONs into the code, just dump and oops and keep going
if you can. If it's a filesystem or a device, turn it read only so
that people notice right away.

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