selftests/mm: fix unused variable warnings in hugetlb-madvise.c, migration.c

Dummy variables are required in order to make these two (similar)
routines work, so in both cases, declare the variables as volatile in
order to avoid the clang compiler warning.

Furthermore, in order to ensure that each test actually does what is
intended, add an asm volatile invocation (thanks to David Hildenbrand
for the suggestion), with a clarifying comment so that it survives
future maintenance.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: John Hubbard <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Tested-by: Muhammad Usama Anjum <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions