Re: [PATCH] Fix generic hugetlb pte check return type.

[David Howells]

David Miller <davem@xxxxxxxxxxxxx> wrote:

> The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
> calls to the pte_*() implementations won't work in certain situations.
> 
> x86 and sparc, for example, return "unsigned long" from the bit
> checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
> 
> But since huge_pte_*() returns 'int', if any high bits on 64-bit are
> relevant, they get chopped off.
> 
> The net effect is that we can loop forever trying to COW a huge page,
> because the huge_pte_write() check signals false all the time.
> 
> Reported-by: Gurudas Pai <gurudas.pai@xxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>

Acked-by: David Howells <dhowells@xxxxxxxxxx>
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