.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH PR_SET_MM_START_BRK 2const 2025-05-17 "Linux man-pages 6.16"
.SH NAME
PR_SET_MM_START_BRK
\-
modify kernel memory map descriptor fields
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.BR "#include <linux/prctl.h>" "  /* Definition of " PR_* " constants */"
.B #include <sys/prctl.h>
.P
.BI "int prctl(PR_SET_MM, PR_SET_MM_START_BRK, unsigned long " addr ", 0L, 0L);"
.fi
.SH DESCRIPTION
Set the address above which the program heap can be expanded with
.BR brk (2)
call.
.P
The address must be greater than the ending address of
the current program data segment.
In addition,
the combined size of the resulting heap and the data segment
can't exceed the
.B RLIMIT_DATA
resource limit (see
.BR setrlimit (2)).
.SH RETURN VALUE
On success,
0 is returned.
On error, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EINVAL
.I addr
is greater than
.B TASK_SIZE
(the limit on the size of the user address space for this architecture).
.TP
.B EINVAL
.I addr
is less than or equal to the end of the data segment
or specifies a value that would cause the
.B RLIMIT_DATA
resource limit to be exceeded.
.SH STANDARDS
Linux.
.SH HISTORY
Linux 3.3.
.\" commit 028ee4be34a09a6d48bdf30ab991ae933a7bc036
.SH SEE ALSO
.BR prctl (2),
.BR PR_SET_MM (2const)