KVM: selftests: do not require 64GB in set_memory_region_test

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: 3c95b97c53e2 ("KVM: selftests: Fix mapping length truncation in m{,un}map()")
Tested-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/kvm/20210701160425.33666-1-borntraeger@de.ibm.com/
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index d8812f27648ca50eecacef6b0f35761a556e349d..d31f54ac4e98244d2676ac1b28561d8d4da75340 100644 (file)
--- 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));