2018-11-15 18:11:34

by Ahmed Abd El Mawgood

Subject: [PATCH] SelfTest: KVM: Drop Asserts for madvise failures

From: Ahmed Abd El Mawgood <[email protected]>

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 <[email protected]>
---
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);
+ } else if (src_type == VM_MEM_SRC_ANONYMOUS_THP) {
+ madvise(region->host_mem, npages * vm->page_size,
+ MADV_HUGEPAGE);
}

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

2018-11-16 09:13:53

by Andrew Jones

Subject: Re: [PATCH] SelfTest: KVM: Drop Asserts for madvise failures

On Thu, Nov 15, 2018 at 08:09:07PM +0200, Ahmed Abd El Mawgood wrote:
> From: Ahmed Abd El Mawgood <[email protected]>
>
> 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 <[email protected]>
> ---
> 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