* Bug? Sparc linux defines MAP_LOCKED == MAP_GROWSDOWN
@ 2003-01-18 3:29 Jamie Lokier
2003-01-18 8:12 ` David S. Miller
0 siblings, 1 reply; 4+ messages in thread
From: Jamie Lokier @ 2003-01-18 3:29 UTC (permalink / raw)
To: linux-kernel, sparclinux, davem
On Sparc and Sparc64, MAP_LOCKED and MAP_GROWSDOWN are both defined
as 0x100. This is a bug, isn't it?
-- Jamie
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Bug? Sparc linux defines MAP_LOCKED == MAP_GROWSDOWN
2003-01-18 3:29 Bug? Sparc linux defines MAP_LOCKED == MAP_GROWSDOWN Jamie Lokier
@ 2003-01-18 8:12 ` David S. Miller
2003-01-18 8:53 ` Jamie Lokier
0 siblings, 1 reply; 4+ messages in thread
From: David S. Miller @ 2003-01-18 8:12 UTC (permalink / raw)
To: jamie; +Cc: linux-kernel, sparclinux
From: Jamie Lokier <jamie@shareable.org>
Date: Sat, 18 Jan 2003 03:29:40 +0000
On Sparc and Sparc64, MAP_LOCKED and MAP_GROWSDOWN are both defined
as 0x100. This is a bug, isn't it?
Unfortunately it's one we're going to have to live with somehow.
Probably by just saying MAP_GROWSDOWN is totally unsupported.
I see no real use for it anyways.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Bug? Sparc linux defines MAP_LOCKED == MAP_GROWSDOWN
2003-01-18 8:12 ` David S. Miller
@ 2003-01-18 8:53 ` Jamie Lokier
2003-01-18 11:49 ` David S. Miller
0 siblings, 1 reply; 4+ messages in thread
From: Jamie Lokier @ 2003-01-18 8:53 UTC (permalink / raw)
To: David S. Miller; +Cc: linux-kernel, sparclinux
David S. Miller wrote:
> From: Jamie Lokier <jamie@shareable.org>
> Date: Sat, 18 Jan 2003 03:29:40 +0000
>
> On Sparc and Sparc64, MAP_LOCKED and MAP_GROWSDOWN are both defined
> as 0x100. This is a bug, isn't it?
>
> Unfortunately it's one we're going to have to live with somehow.
> Probably by just saying MAP_GROWSDOWN is totally unsupported.
> I see no real use for it anyways.
I've never seen the point of it either - MAP_GROWSDOWN just allows the
stack to grow until it overwrites the next vma down, as far as I can
tell. No guard page or anything.
I think MAP_GROWSDOWN should simply be deleted on all architectures
(some don't support it even though they define the flag anyway).
However if that doesn't happen, isn't it best if MAP_LOCKED on the
Sparc _doesn't_ imply MAP_GROWSDOWN? That could lead to some peculiar
failure modes, if a program pokes an unmapped address (which a few do
for one reason or another) and happens to have a MAP_LOCKED region
above it.
I.e. I suggest renumbering MAP_GROWSDOWN in <asm-sparc{,64}/mman.h>.
Nobody in userspace will be using that, whereas there probably are a
few programs using MAP_LOCKED, and getting MAP_GROWSDOWN behaviour as
a bonus is a genuine bug.
cheers,
-- Jamie
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: Bug? Sparc linux defines MAP_LOCKED == MAP_GROWSDOWN
2003-01-18 8:53 ` Jamie Lokier
@ 2003-01-18 11:49 ` David S. Miller
0 siblings, 0 replies; 4+ messages in thread
From: David S. Miller @ 2003-01-18 11:49 UTC (permalink / raw)
To: jamie; +Cc: linux-kernel, sparclinux
From: Jamie Lokier <jamie@shareable.org>
Date: Sat, 18 Jan 2003 08:53:31 +0000
I.e. I suggest renumbering MAP_GROWSDOWN in <asm-sparc{,64}/mman.h>.
Nobody in userspace will be using that, whereas there probably are a
few programs using MAP_LOCKED, and getting MAP_GROWSDOWN behaviour as
a bonus is a genuine bug.
I agree.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2003-01-18 11:51 UTC | newest]
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2003-01-18 3:29 Bug? Sparc linux defines MAP_LOCKED == MAP_GROWSDOWN Jamie Lokier
2003-01-18 8:12 ` David S. Miller
2003-01-18 8:53 ` Jamie Lokier
2003-01-18 11:49 ` David S. Miller
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