Re: [PATCH] mmap.2: mmap with address NULL and MAP_FIXED results in EPERM
From: Michal Hocko
Date: Fri Jun 16 2017 - 11:25:54 EST
On Thu 15-06-17 12:09:01, Theodore Dubois wrote:
> This can be verified with a simple test program. I'm not sure if this is
> a kernel bug or a documentation bug, though...
THis is not a bug. You are not allowed to mmap anything below
/proc/sys/vm/mmap_min_addr. So your patch to update documentation would
have to mention this sysctl to be correct.
> man2/mmap.2 | 7 +++++++
> 1 file changed, 7 insertions(+)
> diff --git a/man2/mmap.2 b/man2/mmap.2
> index d1942b52a..58361c837 100644
> --- a/man2/mmap.2
> +++ b/man2/mmap.2
> @@ -515,6 +515,13 @@ was mounted no-exec.
> .\" (Since 2.4.25 / 2.6.0.)
> .B EPERM
> +.I addr
> +argument is 0 and
> +.B MAP_FIXED
> +is specified.
> +.B EPERM
> The operation was prevented by a file seal; see
> .BR fcntl (2).