On Wed, 2018-08-01 at 17:12 -0700, Andrew Morton wrote:
On Thu, 2 Aug 2018 00:36:36 +0100 Dmitry Safonov dima@arista.com wrote:
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.
...
--- /dev/null +++ b/tools/testing/selftests/vm/map_populate.c
...
+#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)
This is userspace. Why not use assert()?
I wanted to print errno too. Of cause it's possible to get it from coredump - but I think it's easier if you get buildbot reply to see what the error is from the log.
...
+int main(int argc, char **argv) +{
- int sock[2], child, ret;
- FILE *ftmp;
- unsigned long *smap;
- ftmp = tmpfile();
Seems odd to putz around with stdio when you just want the fd. mkstemp(), maybe?
It needs a template and unlink() call.. I can do it. I initially thought about memfd_create(), can change it that way. The only downside is that it will be syscall(NR_memfd_create,...)
- 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));
+}
...
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