Messages in this thread Patch in this message | | | Subject | Re: [PATCH] KVM: selftests: Fix mapping length truncation in m{,un}map() | From | Christian Borntraeger <> | Date | Wed, 30 Jun 2021 10:23:20 +0200 |
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On 30.06.21 09:37, Christian Borntraeger wrote: > > > On 24.06.21 09:09, Zenghui Yu wrote: >> max_mem_slots is now declared as uint32_t. The result of (0x200000 * 32767) >> is unexpectedly truncated to be 0xffe00000, whilst we actually need to >> allocate about, 63GB. Cast max_mem_slots to size_t in both mmap() and >> munmap() to fix the length truncation. >> >> We'll otherwise see the failure on arm64 thanks to the access_ok() checking >> in __kvm_set_memory_region(), as the unmapped VA happen to go beyond the >> task's allowed address space. >> >> # ./set_memory_region_test >> Allowed number of memory slots: 32767 >> Adding slots 0..32766, each memory region with 2048K size >> ==== Test Assertion Failure ==== >> set_memory_region_test.c:391: ret == 0 >> pid=94861 tid=94861 errno=22 - Invalid argument >> 1 0x00000000004015a7: test_add_max_memory_regions at set_memory_region_test.c:389 >> 2 (inlined by) main at set_memory_region_test.c:426 >> 3 0x0000ffffb8e67bdf: ?? ??:0 >> 4 0x00000000004016db: _start at :? >> KVM_SET_USER_MEMORY_REGION IOCTL failed, >> rc: -1 errno: 22 slot: 2615 >> >> Fixes: 3bf0fcd75434 ("KVM: selftests: Speed up set_memory_region_test") >> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com> > > While likely correct, this now breaks on many test systems in our CI that have less memory than 64GB. > (We do get ENOMEM). I have not seen the ENOMEM failures in earlier versions. Strange
As we do not need the memory, the following seems to do the trick (MAP_NORESERVE)
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c index d8812f27648c..0fc68371fb1b 100644 --- a/tools/testing/selftests/kvm/set_memory_region_test.c +++ b/tools/testing/selftests/kvm/set_memory_region_test.c @@ -377,7 +377,7 @@ 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));
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