Re: CONFIG_DEBUG_PAGEALLOC and virt_addr_valid()

[Dave Hansen]

On Thu, 2004-04-01 at 11:11, Sridhar Samudrala wrote:
> When CONFIG_DEBUG_PAGEALLOC is enabled, i am noticing that virt_addr_valid()
> (called from sctp_is_valid_kaddr()) is returning true even for freed objects.
> Is this a bug or expected behavior?

It's expected.  Right now it just makes sure the address translates to a
valid pfn.  Figuring out whether there are actually pagetables
underneath that address would require a pagetable walk.  

Don't we unmap things when they are free'd with CONFIG_DEBUG_PAGEALLOC? 
I guess we could add a pagetable walk in the debug case to
virt_addr_valid(), but it would probably make CONFIG_DEBUG_PAGEALLOC
even more of a dog than it already is.  

-- Dave

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