4.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andrea Arcangeli <[email protected]> commit 1ac25013fb9e4ed595cd608a406191e93520881e upstream. hugetlb needs the same fix as faultin_nopage (which was applied in commit 96312e61282a ("mm/gup.c: teach get_user_pages_unlocked to handle FOLL_NOWAIT")) 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. Link: http://lkml.kernel.org/r/[email protected] Fixes: ce53053ce378 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()") Signed-off-by: Andrea Arcangeli <[email protected]> Tested-by: "Dr. David Alan Gilbert" <[email protected]> Reported-by: "Dr. David Alan Gilbert" <[email protected]> Reviewed-by: Mike Kravetz <[email protected]> Reviewed-by: Peter Xu <[email protected]> Cc: Mike Rapoport <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/hugetlb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4269,7 +4269,8 @@ long follow_hugetlb_page(struct mm_struc break; } if (ret & VM_FAULT_RETRY) { - if (nonblocking) + if (nonblocking && + !(fault_flags & FAULT_FLAG_RETRY_NOWAIT)) *nonblocking = 0; *nr_pages = 0; /*
