Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 24 Aug 2010 10:51:12 -0700 | Subject | Re: [PATCH] guard page for stacks that grow upwards |
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Hmm. Looking at the patch a bit more..
On Tue, Aug 24, 2010 at 9:31 AM, Luck, Tony <tony.luck@intel.com> wrote: > > +#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) > + else if (vma->vm_flags & VM_GROWSUP) { > + address = PAGE_ALIGN(address + 1); > + if (address == vma->vm_end) {
So I react to two things:
- that "else" looks wrong. At least conceptually, both could happen - the code should be entirely able to handle a segment that expands both ways (which is something that ia64 could do: stack one way, register spills etc other, all in just one happy vma). I guess we don't set it up that way now, but the "else" just annoys my sense of aesthetics. It's an extra four letters that don't add value - just takes it away.
- The "address = PAGE_ALIGN(address + 1);" thing is just ugly. Wouldn't it be nicer to just move the earlier
address &= PAGE_MASK
back outside the conditionals (and keep the original conditional the way it was - you only changed it for that bogus "else" case anyway), and then do
if (address + PAGE_SIZE == vma->vm_end)
rather than have "PAGE_ALIGN(address + 1)" as yet another way of aligning the address just right.
No?
Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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