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

On Friday August 10, [email protected] wrote:
> On 8/1/07, Neil Brown <[email protected]> wrote:
> 
> > No, this does not use indefinite stack.
> >
> > loop will schedule each request to be handled by a kernel thread, so
> > requests to 'loop' are serialised, never stacked.
> >
> > In 2.6.22, generic_make_request detects and serialises recursive calls,
> > so unlimited recursion is not possible there either.
> 
> Is that saying "before 2.6.22, a read/write on a deeply layered device
> would use a lot of stack?"

before 2.6.22, a stack of dm and/or md devices (not loop, and not
md/raid0 or md/linear) would use more stack the more devices were
involved.  If you made a very deep stack, you could push the stack
over any limit you chose.

I won't say "a lot of stack" as I haven't measured the exact amount,
just "more stack as you add more devices".

NeilBrown
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• References:
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Rene Herman <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Matt Mackall <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Andrea Arcangeli <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Alan Cox <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Eric Sandeen <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Alan Cox <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: "Satyam Sharma" <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Eric Sandeen <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: "Dan Merillat" <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: Neil Brown <[email protected]>
  • Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?
    • From: "Dan Merillat" <[email protected]>

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