As many other projects, we use some shmalloc allocator. At some point we need to make a part of allocated pages back private to process. And it should be populated straight away. Check that (MAP_PRIVATE | MAP_POPULATE) actually copies the private page.
Cc: Andrew Morton akpm@linux-foundation.org Cc: Dmitry Safonov 0x7f454c46@gmail.com Cc: Hua Zhong hzhong@arista.com Cc: Shuah Khan shuah@kernel.org Cc: Stuart Ritchie sritchie@arista.com Cc: linux-kselftest@vger.kernel.org Signed-off-by: Dmitry Safonov dima@arista.com --- tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/map_populate.c | 113 ++++++++++++++++++++++++++++++ tools/testing/selftests/vm/run_vmtests | 11 +++ 4 files changed, 126 insertions(+) create mode 100644 tools/testing/selftests/vm/map_populate.c
diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore index 342c7bc9dc8c..af5ff83f6d7f 100644 --- a/tools/testing/selftests/vm/.gitignore +++ b/tools/testing/selftests/vm/.gitignore @@ -1,6 +1,7 @@ hugepage-mmap hugepage-shm map_hugetlb +map_populate thuge-gen compaction_test mlock2-tests diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index fdefa2295ddc..9881876d2aa0 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -12,6 +12,7 @@ TEST_GEN_FILES += gup_benchmark TEST_GEN_FILES += hugepage-mmap TEST_GEN_FILES += hugepage-shm TEST_GEN_FILES += map_hugetlb +TEST_GEN_FILES += map_populate TEST_GEN_FILES += mlock-random-test TEST_GEN_FILES += mlock2-tests TEST_GEN_FILES += on-fault-limit diff --git a/tools/testing/selftests/vm/map_populate.c b/tools/testing/selftests/vm/map_populate.c new file mode 100644 index 000000000000..df3eacc8eecb --- /dev/null +++ b/tools/testing/selftests/vm/map_populate.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2018 Dmitry Safonov, Arista Networks + * + * MAP_POPULATE | MAP_PRIVATE should COW VMA pages. + */ + +#define _GNU_SOURCE +#include <errno.h> +#include <fcntl.h> +#include <sys/mman.h> +#include <sys/socket.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#ifndef MMAP_SZ +#define MMAP_SZ 4096 +#endif + +#define BUG_ON(condition, description) \ + do { \ + if (condition) { \ + fprintf(stderr, "[FAIL]\t%s:%d\t%s:%s\n", __func__, \ + __LINE__, (description), strerror(errno)); \ + exit(1); \ + } \ + } while (0) + +static int parent_f(int sock, unsigned long *smap, int child) +{ + int status, ret; + + ret = read(sock, &status, sizeof(int)); + BUG_ON(ret <= 0, "read(sock)"); + + *smap = 0x22222BAD; + ret = msync(smap, MMAP_SZ, MS_SYNC); + BUG_ON(ret, "msync()"); + + ret = write(sock, &status, sizeof(int)); + BUG_ON(ret <= 0, "write(sock)"); + + waitpid(child, &status, 0); + BUG_ON(!WIFEXITED(status), "child hasn't suicide by own will"); + + return WEXITSTATUS(status); +} + +static int child_f(int sock, unsigned long *smap, int fd) +{ + int ret, buf = 0; + + smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_POPULATE, fd, 0); + BUG_ON(smap == MAP_FAILED, "mmap()"); + + BUG_ON(*smap != 0xdeadbabe, "MAP_PRIVATE | MAP_POPULATE changed file"); + + ret = write(sock, &buf, sizeof(int)); + BUG_ON(ret <= 0, "write(sock)"); + + ret = read(sock, &buf, sizeof(int)); + BUG_ON(ret <= 0, "read(sock)"); + + BUG_ON(*smap == 0x22222BAD, "MAP_POPULATE didn't COW private page"); + BUG_ON(*smap != 0xdeadbabe, "mapping was corrupted"); + + return 0; +} + +int main(int argc, char **argv) +{ + int sock[2], child, ret; + FILE *ftmp; + unsigned long *smap; + + ftmp = tmpfile(); + BUG_ON(ftmp == 0, "tmpfile()"); + + ret = ftruncate(fileno(ftmp), MMAP_SZ); + BUG_ON(ret, "ftruncate()"); + + smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE, + MAP_SHARED, fileno(ftmp), 0); + BUG_ON(smap == MAP_FAILED, "mmap()"); + + *smap = 0xdeadbabe; + /* Probably unnecessary, but let it be. */ + ret = msync(smap, MMAP_SZ, MS_SYNC); + BUG_ON(ret, "msync()"); + + ret = socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sock); + BUG_ON(ret, "socketpair()"); + + child = fork(); + BUG_ON(child == -1, "fork()"); + + if (child) { + ret = close(sock[0]); + BUG_ON(ret, "close()"); + + return parent_f(sock[1], smap, child); + } + + ret = close(sock[1]); + BUG_ON(ret, "close()"); + + return child_f(sock[0], smap, fileno(ftmp)); +} diff --git a/tools/testing/selftests/vm/run_vmtests b/tools/testing/selftests/vm/run_vmtests index 88cbe5575f0c..584a91ae4a8f 100755 --- a/tools/testing/selftests/vm/run_vmtests +++ b/tools/testing/selftests/vm/run_vmtests @@ -168,6 +168,17 @@ else fi
echo "--------------------" +echo "running map_populate" +echo "--------------------" +./map_populate +if [ $? -ne 0 ]; then + echo "[FAIL]" + exitcode=1 +else + echo "[PASS]" +fi + +echo "--------------------" echo "running mlock2-tests" echo "--------------------" ./mlock2-tests