Re: [PATCH 3/3] 2.6.8-rc4-mm1 - UML fixes

[William Lee Irwin III]

wli@xxxxxxxxxxxxxx said:
>> Out of curiosity, why are you allocating 4*PAGE_SIZE for the stack if
>> you're only going to use 2*PAGE_SIZE of it? I saw no other users for
>> the rest of ->thread_info offhand. 

On Thu, Aug 12, 2004 at 01:41:18AM -0400, Jeff Dike wrote:
> Well, that's slightly misleading.  The other two pages (minus the thread_info)
> are available for stack if needed.  UML stacks are somewhat larger than the
> native kernel stacks because of the userspace signal frames, so I allocate
> 4 pages for now to be safe.

This might confuse CONFIG_DEBUG_PAGEALLOC, which uses THREAD_SIZE to
detect the end of the kernel stack in store_stackinfo() in mm/slab.c
and kstack_end() in include/linux/sched.h, and the sizing heuristic
for max_threads in fork_init().

Also, how is this meant to interoperate with CONFIG_KERNEL_STACK_ORDER?
It seems to ignore the setting from the config option.


-- wli
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