mm: Fix generic hugetlb pte check return type.
authorDavid Miller <davem@davemloft.net>
Wed, 2 Oct 2013 18:25:09 +0000 (14:25 -0400)
committerDavid S. Miller <davem@davemloft.net>
Thu, 3 Oct 2013 00:02:35 +0000 (20:02 -0400)
commit26794942461f438a6bc725ec7294b08a6bd782c4
treea6357a628342e523374e08f926bcd9794acdea9b
parent20928bd3f08afb036c096d9559d581926b895918
mm: Fix generic hugetlb pte check return type.

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@oracle.com>
Tested-by: Gurudas Pai <gurudas.pai@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: David Rientjes <rientjes@google.com>
include/asm-generic/hugetlb.h