hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()
hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()

This patch fixes possible deadlock in hugepage lock_page()
by adding missing unlock_page().

libhugetlbfs test will hit this bug when the next patch in this
patchset ("hugetlb, HWPOISON: move PG_HWPoison bit check") is applied.

Signed-off-by: Naoya Horiguchi <8e7a128cd0264d3269a891fb3e87507c2985f8af@ah.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <3576fcbd7ffa3776a92ac17fc90ba38e23f75e95@ce.jp.nec.com>
Acked-by: Fengguang Wu <24f7fe9d205c8a9f6ade0c2894e14303ca16087f@intel.com>
Signed-off-by: Andi Kleen <0474aee45985f5ae829f53849df476200e876990@linux.intel.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs