[LTP] [PATCH 1/1] brk02: Add test for removing more than one VMA

Petr Vorel
2021-02-12T10:27:19Z

Hi Liam,

thanks for your patch. Minor notes below.

> When brk expands, it attempts to expand a VMA. This expansion will
> succeed depending on the anonymous VMA chain and if the vma flags are
> compatible. This test expands brk() then calls mprotect to ensure the
> next brk call will create a new VMA, then it calls brk a final time to
> restore the first brk address. The test is the final brk call which
> will remove more than an entire VMA from the vm area.

> Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
> ---
> testcases/kernel/syscalls/brk/brk02.c | 49 +++++++++++++++++++++++++++
> 1 file changed, 49 insertions(+)
> create mode 100644 testcases/kernel/syscalls/brk/brk02.c

> diff --git a/testcases/kernel/syscalls/brk/brk02.c b/testcases/kernel/syscalls/brk/brk02.c
> new file mode 100644
> index 000000000..834fe9f2f
> --- /dev/null
> +++ b/testcases/kernel/syscalls/brk/brk02.c
> @@ -0,0 +1,49 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2021 Liam R. Howlett <liam.howlett@oracle.com>
> + *
> + *
nit: blank line
> + * Expand the brk by 2 pages to ensure there is a newly created VMA and not
> + * expanding the original due to multiple anon pages. mprotect that new VMA
> + * then brk back to the original address therefore causing a munmap of at
> + * least one full VMA.
> + */
> +
> +#include <unistd.h>
> +#include <stdint.h>
nit: Not sure if <stdint.h> is needed.

> +#include <sys/mman.h>
> +
> +#include "tst_test.h"
> +
> +void brk_down_vmas(void)
> +{
> + void *brk_addr = sbrk(0);
> + unsigned long page_size = getpagesize();
> + void *addr = brk_addr + page_size;
> +
> + if (brk(addr))
> + return;
> +
> + addr += page_size;
> + if (brk(addr))
> + return;
You need to add tst_ret(TFAIL, "failed due ..."); before each return otherwise
you get error:
tst_test.c:1080: TBROK: Test haven't reported results!

> +
> + if (mprotect(addr - page_size, page_size,
> + PROT_READ|PROT_WRITE|PROT_EXEC))
> + return;
> +
> + addr += page_size;
> + if (brk(addr))
> + return;
> +
> + if (brk(brk_addr))
> + return;
> +
> +
> +
Please remove these blank lines.
> + tst_res(TPASS, "munmap two VMAs of brk() passed.");
> +}
> +
> +static struct tst_test test = {
> + .test_all = brk_down_vmas,
> +};

Kind regards,
Petr