On Thu, Nov 15, 2018 at 08:09:07PM +0200, Ahmed Abd El Mawgood wrote:

From: Ahmed Abd El Mawgood ahmedsoliman@mena.vt.edu

madvise() returns -1 without CONFIG_TRANSPARENT_HUGEPAGE=y. That would trigger asserts when checking for return value of madvice. Following similar decision to [1]. I thought it is ok to assume that madvise() failures implies that THP is not supported by host kernel.

Other options were to check for Transparent Huge Page support in /sys/kernel/mm/transparent_hugepage/enabled.

-- links -- [1] https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg04514.html

Signed-off-by: Ahmed Abd El Mawgood ahmedsoliman@mena.vt.edu

tools/testing/selftests/kvm/lib/kvm_util.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 1b41e71283d5..7725cfdf1b79 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -586,14 +586,12 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm, src_type == VM_MEM_SRC_ANONYMOUS_THP ? huge_page_size : 1); /* As needed perform madvise */

• if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {

• ret = madvise(region->host_mem, npages * vm->page_size,
  

• 	     src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
  

• TEST_ASSERT(ret == 0, "madvise failed,\n"
  

• 	    "  addr: %p\n"
  

• 	    "  length: 0x%lx\n"
  

• 	    "  src_type: %x",
  

• 	    region->host_mem, npages * vm->page_size, src_type);
  

• if (src_type == VM_MEM_SRC_ANONYMOUS) {

• madvise(region->host_mem, npages * vm->page_size,
  

• 		MADV_NOHUGEPAGE);
  

This is fine.

• } else if (src_type == VM_MEM_SRC_ANONYMOUS_THP) {

• madvise(region->host_mem, npages * vm->page_size,
  

• 		MADV_HUGEPAGE);
  

I would still assert here, but with a more informative message like "madvise(MADV_HUGEPAGE) failed. Does the kernel have CONFIG_TRANSPARENT_HUGEPAGE=y?"

} region->unused_phy_pages = sparsebit_alloc(); -- 2.18.1

Thanks, drew