PR_SET_IO_FLUSHER(2const)                            PR_SET_IO_FLUSHER(2const)

NAME
       PR_SET_IO_FLUSHER - change the IO_FLUSHER state

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <linux/prctl.h>  /* Definition of PR_* constants */
       #include <sys/prctl.h>

       int prctl(PR_SET_IO_FLUSHER, long state, 0L, 0L, 0L);

DESCRIPTION
       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.

SEE ALSO
       prctl(2), PR_GET_IO_FLUSHER(2const)

Linux man-pages 6.19              2026-02-08         PR_SET_IO_FLUSHER(2const)