instruction: 0.526
runtime: 0.308
syscall: 0.166



mremap fails with EFAULT if address range overlaps with stack guard
Description of problem:
When running 32-bit user-static on 64-bit host, `mremap` behave differently from the kernel. This difference let programs that call `pthread_getattr_np` on musl-libc to run into a loop on repeated calling `mremap`.

https://git.musl-libc.org/cgit/musl/plain/src/thread/pthread_getattr_np.c

``` c
		while (mremap(p-l-PAGE_SIZE, PAGE_SIZE, 2*PAGE_SIZE, 0)==MAP_FAILED && errno==ENOMEM)
			l += PAGE_SIZE;
```
Steps to reproduce:
Compile the following program against musl-libc arm 32-bit, and run it in qemu-user-static on x86_64 host.

``` c
#define _GNU_SOURCE
#include <pthread.h>

int main(int argc, char *argv[]) {
	pthread_attr_t attr;
	return pthread_getattr_np(pthread_self(), &attr);
}
```

For example, on x86_64 fedora 38 with podman and qemu-user-static installed, we can reproduce this with alpine container:

```
$ podman run --rm -it --arch arm/v7 docker.io/library/alpine:latest

/ # apk add alpine-sdk

......

/ # cat test.c
#define _GNU_SOURCE
#include <pthread.h>

int main(int argc, char *argv[]) {
	pthread_attr_t attr;
	return pthread_getattr_np(pthread_self(), &attr);
}

/ # gcc test.c

/ # ./a.out
```
Additional information:
Original thread on musl mail list where this was initially reported: https://www.openwall.com/lists/musl/2017/06/15/9