Re: [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning

From: Dave Hansen
Date: Wed Sep 26 2018 - 11:41:45 EST


On 09/26/2018 12:38 AM, Michal Hocko wrote:
> Why cannot you simply go with [no]vm_page_poison[=on/off]?

I was trying to look to the future a bit, if we end up with five or six
more other options we want to allow folks to enable/disable. I don't
want to end up in a situation where we have a bunch of different knobs
to turn all this stuff off at runtime.

I'd really like to have one stop shopping so that folks who have a
system that's behaving well and don't need any debugging can get some of
their performance back.

But, the *primary* thing we want here is a nice, quick way to turn as
much debugging off as we can. A nice-to-have is a future-proof,
slub-style option that will centralize things.

Alex's patch fails at the primary goal, IMNHO because "vm_debug=-" is so
weird. I'd much rather have "vm_debug=off" (the primary goal) and throw
away the nice-to-have (future-proof fine-grained on/off).

I think we can have both, but I guess the onus is on me to go and add a
strcmp(..., "off"). :)