[PATCH] KVM: selftests: do not require 64GB in set_memory_region_test

[PATCH] KVM: selftests: do not require 64GB in set_memory_region_test

[Christian Borntraeger]

Unless the user sets overcommit_memory or has plenty of swap, the latest
changes to the testcase will result in ENOMEM failures for hosts with
less than 64GB RAM. As we do not use much of the allocated memory, we
can use MAP_NORESERVE to avoid this error.

Cc: Zenghui Yu <yuzenghui@huawei.com>
Cc: vkuznets@redhat.com
Cc: wanghaibin.wang@huawei.com
Cc: stable@vger.kernel.org
Fixes: 309505dd5685 ("KVM: selftests: Fix mapping length truncation in m{,un}map()")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 tools/testing/selftests/kvm/set_memory_region_test.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index d8812f27648c..d31f54ac4e98 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -377,7 +377,8 @@ static void test_add_max_memory_regions(void)
 		(max_mem_slots - 1), MEM_REGION_SIZE >> 10);
 
 	mem = mmap(NULL, (size_t)max_mem_slots * MEM_REGION_SIZE + alignment,
-		   PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+		   PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
 	TEST_ASSERT(mem != MAP_FAILED, "Failed to mmap() host");
 	mem_aligned = (void *)(((size_t) mem + alignment - 1) & ~(alignment - 1));
 
-- 
2.31.1

Re: [PATCH] KVM: selftests: do not require 64GB in set_memory_region_test

[Zenghui Yu]

On 2021/7/2 0:04, Christian Borntraeger wrote:
> Unless the user sets overcommit_memory or has plenty of swap, the latest
> changes to the testcase will result in ENOMEM failures for hosts with
> less than 64GB RAM. As we do not use much of the allocated memory, we
> can use MAP_NORESERVE to avoid this error.

Had a go on arm64:

Tested-by: Zenghui Yu <yuzenghui@huawei.com>

Thanks,
Zenghui