hugetlb needs the same fix as faultin_nopage (which was applied in
96312e61282ae3f6537a562625706498cbc75594) or KVM hangs because it
thinks the mmap_sem was already released by hugetlb_fault() if it
returned VM_FAULT_RETRY, but it wasn't in the FOLL_NOWAIT case.
Fixes: ce53053ce378 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()")
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Tested-by: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Reported-by: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
---
mm/hugetlb.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e37efd5d8318..b3622d7888c8 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4301,7 +4301,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
break;
}
if (ret & VM_FAULT_RETRY) {
- if (nonblocking)
+ if (nonblocking &&
+ !(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
*nonblocking = 0;
*nr_pages = 0;
/*
