From 1caed86022b9eb927283d8b2cdd7216baf43029e Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Tue, 21 Aug 2018 21:53:47 -0700 Subject: tools/testing/selftests/vm/: add MAP_POPULATE test As with 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. [akpm@linux-foundation.org: change message, per review discussion] Link: http://lkml.kernel.org/r/20180801233636.29354-1-dima@arista.com Signed-off-by: Dmitry Safonov Reviewed-by: Andrew Morton Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Hua Zhong Cc: Shuah Khan Cc: Stuart Ritchie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- tools/testing/selftests/vm/map_populate.c | 113 ++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 tools/testing/selftests/vm/map_populate.c (limited to 'tools/testing/selftests/vm/map_populate.c') diff --git a/tools/testing/selftests/vm/map_populate.c b/tools/testing/selftests/vm/map_populate.c new file mode 100644 index 000000000000..6b8aeaa0bf7a --- /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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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 in unexpected state"); + + 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)); +} -- cgit v1.2.3