pr_set_io_flusher(2const) - BetterMan

pr_set_io_flusher(2const)

change the IO_FLUSHER state

distropkg manpages-dev@6.9.1-1dataset 2026-04-01T06:19:02Z+debian+ec4110e+mandoc:1.14.6-4

Synopsis

#include <linux/prctl.h>
  /* Definition of 
PR_*
 constants */
#include <sys/prctl.h>
int prctl(PR_SET_IO_FLUSHER, long 
state
, 0L, 0L, 0L);

—

Options · 1

EINVAL

state is not a valid value.

NAME

PR_SET_IO_FLUSHER - change the IO_FLUSHER state

SYNOPSIS

bash

#include <linux/prctl.h>\n  /* Definition of \nPR_*\n constants */
\n#include <sys/prctl.h>

bash

int prctl(PR_SET_IO_FLUSHER, long \nstate\n, 0L, 0L, 0L);

If a user process is involved in the block layer or filesystem I/O path, and can allocate memory while processing I/O requests it must set state to 1. This will put the process in the IO_FLUSHER state, which allows it special treatment to make progress when allocating memory. If state is 0, the process will clear the IO_FLUSHER state, and the default behavior will be used.

The calling process must have the CAP_SYS_RESOURCE capability.

The IO_FLUSHER state is inherited by a child process created via fork(2) and is preserved across execve(2).

Examples of IO_FLUSHER applications are FUSE daemons, SCSI device emulation daemons, and daemons that perform error handling like multipath path recovery applications.

RETURN VALUE

On success, 0 is returned. On error, -1 is returned, and errno is set to indicate the error.

ERRORS

EINVAL: state is not a valid value.

STANDARDS

Linux.

HISTORY

Linux 5.6.