Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

[Andrea Arcangeli <andrea@suse.de>]

On Wed, Jul 18, 2007 at 08:37:25PM -0500, Matt Mackall wrote:
> Turn on irqstacks when using 8k stacks

Indeed.

> Detect when usage with 8k stacks would overrun a 4k stack when doing
>  our stack switch and do a WARN_ONCE
> Fix up the damn bugs

I don't think they're necessarily bugs. IMHO the WARN_ON is better off
at 7k level like it is today with the current STACK_WARN. 4k for a
stack for common code really is small. I doubt you're going to find
obvious culprits that way, more likely you'll have to mangle the code
to call kmalloc for fairly small structures which isn't necessarily a
good thing in the long term. It comes to mind the folio ptes array
that Hugh allocated on the stack in his large PAGE_SIZE patch of jul
2001, that thing like any other local array, would need to be
kmalloced with a 4k stack. With 4k I'm afraid you better not use the
stack for anything but pointers, especially if you run in common code
that may invoke I/O like that.