Messages in this thread | | | Subject | Re: [PATCH] selftests/vm: Add test to validate mirror functionality with mremap | From | Anshuman Khandual <> | Date | Fri, 21 Jul 2017 16:08:23 +0530 |
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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@oracle.com> >> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> >> --- >> 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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