On 07/21/2017 04:49 AM, Mike Kravetz wrote:
> On 07/20/2017 02:36 AM, Anshuman Khandual wrote:
>> This adds a test to validate mirror functionality with mremap()
>> system call on shared anon mappings.
>>
>> Suggested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
>> Signed-off-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
>> ---
>> tools/testing/selftests/vm/Makefile | 1 +
>> .../selftests/vm/mremap_mirror_shared_anon.c | 54 ++++++++++++++++++++++
>
> This may be a better fit in LTP where there are already several other
> mremap tests. I honestly do not know the best place for such a test.
Yeah but these days self tests try to target smaller functional
tests which can run quickly and validate something, hence thought
this may be appropriate as a self test.
>
>> 2 files changed, 55 insertions(+)
>> create mode 100644 tools/testing/selftests/vm/mremap_mirror_shared_anon.c
>>
>> diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
>> index cbb29e4..11657ff5 100644
>> --- a/tools/testing/selftests/vm/Makefile
>> +++ b/tools/testing/selftests/vm/Makefile
>> @@ -17,6 +17,7 @@ TEST_GEN_FILES += transhuge-stress
>> TEST_GEN_FILES += userfaultfd
>> TEST_GEN_FILES += mlock-random-test
>> TEST_GEN_FILES += virtual_address_range
>> +TEST_GEN_FILES += mremap_mirror_shared_anon
>>
>> TEST_PROGS := run_vmtests
>>
>> diff --git a/tools/testing/selftests/vm/mremap_mirror_shared_anon.c b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c
>> new file mode 100644
>> index 0000000..b0adbb2
>> --- /dev/null
>> +++ b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c
>> @@ -0,0 +1,54 @@
>> +/*
>> + * Test to verify mirror functionality with mremap() system
>> + * call for shared anon mappings.
>> + *
>> + * Copyright (C) 2017 Anshuman Khandual, IBM Corporation
>> + *
>> + * Licensed under GPL V2
>> + */
>> +#include <stdio.h>
>> +#include <string.h>
>> +#include <unistd.h>
>> +#include <errno.h>
>> +#include <sys/mman.h>
>> +#include <sys/time.h>
>> +
>> +#define PATTERN 0xbe
>> +#define ALLOC_SIZE 0x10000UL /* Works for 64K and 4K pages */
>
> Why hardcode? You could use sysconf to get page size and use some
> multiple of that.
Sure, will do that.
>
>> +
>> +int test_mirror(char *old, char *new, unsigned long size)
>> +{
>> + unsigned long i;
>> +
>> + for (i = 0; i < size; i++) {
>> + if (new[i] != old[i]) {
>> + printf("Mismatch at new[%lu] expected "
>> + "%d received %d\n", i, old[i], new[i]);
>> + return 1;
>> + }
>> + }
>> + return 0;
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> + char *ptr, *mirror_ptr;
>> +
>> + ptr = mmap(NULL, ALLOC_SIZE, PROT_READ | PROT_WRITE,
>> + MAP_SHARED | MAP_ANONYMOUS, -1, 0);
>> + if (ptr == MAP_FAILED) {
>> + perror("map() failed");
>> + return -1;
>> + }
>> + memset(ptr, PATTERN, ALLOC_SIZE);
>> +
>> + mirror_ptr = (char *) mremap(ptr, 0, ALLOC_SIZE, 1);
>
> Why hardcode 1? You really want the MREMAP_MAYMOVE flag. Right?
Right, missed that. My bad.
>
>> + if (mirror_ptr == MAP_FAILED) {
>> + perror("mremap() failed");
>> + return -1;
>> + }
>> +
>> + if (test_mirror(ptr, mirror_ptr, ALLOC_SIZE))
>> + return 1;
>> + return 0;
>> +}
>
> You may want to expand the test to make sure mremap(old_size == 0)
> fails for private mappings. Of course, this assumes my proposed
> patch gets in. Until then, it will succeed and create a new unrelated
> mapping.
Even without your patch, the data in the new mapping still does
not match the original one. Anyway, will accommodate private
anon mapping as well.
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