|
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | NOTES | CAVEATS | BUGS | EXAMPLES | SEE ALSO | COLOPHON |
|
|
|
mmap(2) System Calls Manual mmap(2)
mmap, munmap - map or unmap files or devices into memory
Standard C library (libc, -lc)
#include <sys/mman.h>
void *mmap(size_t length;
void addr[length], size_t length, int prot, int flags,
int fd, off_t offset);
int munmap(size_t length;
void addr[length], size_t length);
See VERSIONS for information on feature test macro requirements.
mmap() creates a new mapping in the virtual address space of the
calling process. The starting address for the new mapping is
specified in addr. The length argument specifies the length of
the mapping (which must be greater than 0).
If addr is NULL, then the kernel chooses the (page-aligned)
address at which to create the mapping; this is the most portable
method of creating a new mapping. If addr is not NULL, then the
kernel takes it as a hint about where to place the mapping; on
Linux, the kernel will pick a nearby page boundary (but always
above or equal to the value specified by
/proc/sys/vm/mmap_min_addr) and attempt to create the mapping
there. If another mapping already exists there, the kernel picks
a new address that may or may not depend on the hint. The address
of the new mapping is returned as the result of the call.
The contents of a file mapping (as opposed to an anonymous
mapping; see MAP_ANONYMOUS below), are initialized using length
bytes starting at offset offset in the file (or other object)
referred to by the file descriptor fd. offset must be a multiple
of the page size as returned by sysconf(_SC_PAGE_SIZE).
After the mmap() call has returned, the file descriptor, fd, can
be closed immediately without invalidating the mapping.
The prot argument describes the desired memory protection of the
mapping (and must not conflict with the open mode of the file).
It is either PROT_NONE or the bitwise OR of one or more of the
following flags:
PROT_EXEC
Pages may be executed.
PROT_READ
Pages may be read.
PROT_WRITE
Pages may be written.
PROT_NONE
Pages may not be accessed.
The flags argument
The flags argument determines whether updates to the mapping are
visible to other processes mapping the same region, and whether
updates are carried through to the underlying file. This behavior
is determined by including exactly one of the following values in
flags:
MAP_SHARED
Share this mapping. Updates to the mapping are visible to
other processes mapping the same region, and (in the case
of file-backed mappings) are carried through to the
underlying file. (To precisely control when updates are
carried through to the underlying file requires the use of
msync(2).)
MAP_SHARED_VALIDATE (since Linux 4.15)
This flag provides the same behavior as MAP_SHARED except
that MAP_SHARED mappings ignore unknown flags in flags. By
contrast, when creating a mapping using
MAP_SHARED_VALIDATE, the kernel verifies all passed flags
are known and fails the mapping with the error EOPNOTSUPP
for unknown flags. This mapping type is also required to
be able to use some mapping flags (e.g., MAP_SYNC).
MAP_PRIVATE
Create a private copy-on-write mapping. Updates to the
mapping are not visible to other processes mapping the same
file, and are not carried through to the underlying file.
It is unspecified whether changes made to the file after
the mmap() call are visible in the mapped region.
Both MAP_SHARED and MAP_PRIVATE are described in POSIX.1-2001 and
POSIX.1-2008. MAP_SHARED_VALIDATE is a Linux extension.
In addition, zero or more of the following values can be ORed in
flags:
MAP_32BIT (since Linux 2.4.20, 2.6)
Put the mapping into the first 2 Gigabytes of the process
address space. This flag is supported only on x86-64, for
64-bit programs. It was added to allow thread stacks to be
allocated somewhere in the first 2 GB of memory, so as to
improve context-switch performance on some early 64-bit
processors. Modern x86-64 processors no longer have this
performance problem, so use of this flag is not required on
those systems. The MAP_32BIT flag is ignored when
MAP_FIXED is set.
MAP_ANON
Synonym for MAP_ANONYMOUS; provided for compatibility with
other implementations.
MAP_ANONYMOUS
The mapping is not backed by any file; its contents are
initialized to zero. The fd argument is ignored; however,
some implementations require fd to be -1 if MAP_ANONYMOUS
(or MAP_ANON) is specified, and portable applications
should ensure this. The offset argument should be zero.
Support for MAP_ANONYMOUS in conjunction with MAP_SHARED
was added in Linux 2.4.
MAP_DENYWRITE
This flag is ignored. (Long ago—Linux 2.0 and earlier—it
signaled that attempts to write to the underlying file
should fail with ETXTBSY. But this was a source of denial-
of-service attacks.)
MAP_EXECUTABLE
This flag is ignored.
MAP_FILE
Compatibility flag. Ignored.
MAP_FIXED
Don't interpret addr as a hint: place the mapping at
exactly that address. addr must be suitably aligned: for
most architectures a multiple of the page size is
sufficient; however, some architectures may impose
additional restrictions. If the memory region specified by
addr and length overlaps pages of any existing mapping(s),
then the overlapped part of the existing mapping(s) will be
discarded. If the specified address cannot be used, mmap()
will fail.
Software that aspires to be portable should use the
MAP_FIXED flag with care, keeping in mind that the exact
layout of a process's memory mappings is allowed to change
significantly between Linux versions, C library versions,
and operating system releases. Carefully read the
discussion of this flag in NOTES!
MAP_FIXED_NOREPLACE (since Linux 4.17)
This flag provides behavior that is similar to MAP_FIXED
with respect to the addr enforcement, but differs in that
MAP_FIXED_NOREPLACE never clobbers a preexisting mapped
range. If the requested range would collide with an
existing mapping, then this call fails with the error
EEXIST. This flag can therefore be used as a way to
atomically (with respect to other threads) attempt to map
an address range: one thread will succeed; all others will
report failure.
Note that older kernels which do not recognize the
MAP_FIXED_NOREPLACE flag will typically (upon detecting a
collision with a preexisting mapping) fall back to a “non-
MAP_FIXED” type of behavior: they will return an address
that is different from the requested address. Therefore,
backward-compatible software should check the returned
address against the requested address.
MAP_GROWSDOWN
This flag is used for stacks. It indicates to the kernel
virtual memory system that the mapping should extend
downward in memory. The return address is one page lower
than the memory area that is actually created in the
process's virtual address space. Touching an address in
the "guard" page below the mapping will cause the mapping
to grow by a page. This growth can be repeated until the
mapping grows to within a page of the high end of the next
lower mapping, at which point touching the "guard" page
will result in a SIGSEGV signal.
MAP_HUGETLB (since Linux 2.6.32)
Allocate the mapping using "huge" pages. See the Linux
kernel source file
Documentation/admin-guide/mm/hugetlbpage.rst for further
information, as well as NOTES, below.
MAP_HUGE_2MB
MAP_HUGE_1GB (since Linux 3.8)
Used in conjunction with MAP_HUGETLB to select alternative
hugetlb page sizes (respectively, 2 MB and 1 GB) on systems
that support multiple hugetlb page sizes.
More generally, the desired huge page size can be
configured by encoding the base-2 logarithm of the desired
page size in the six bits at the offset MAP_HUGE_SHIFT. (A
value of zero in this bit field provides the default huge
page size; the default huge page size can be discovered via
the Hugepagesize field exposed by /proc/meminfo.) Thus,
the above two constants are defined as:
#define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT)
#define MAP_HUGE_1GB (30 << MAP_HUGE_SHIFT)
The range of huge page sizes that are supported by the
system can be discovered by listing the subdirectories in
/sys/kernel/mm/hugepages.
MAP_LOCKED (since Linux 2.5.37)
Mark the mapped region to be locked in the same way as
mlock(2). This implementation will try to populate
(prefault) the whole range but the mmap() call doesn't fail
with ENOMEM if this fails. Therefore major faults might
happen later on. So the semantic is not as strong as
mlock(2). One should use mmap() plus mlock(2) when major
faults are not acceptable after the initialization of the
mapping. The MAP_LOCKED flag is ignored in older kernels.
MAP_NONBLOCK (since Linux 2.5.46)
This flag is meaningful only in conjunction with
MAP_POPULATE. Don't perform read-ahead: create page tables
entries only for pages that are already present in RAM.
Since Linux 2.6.23, this flag causes MAP_POPULATE to do
nothing. One day, the combination of MAP_POPULATE and
MAP_NONBLOCK may be reimplemented.
MAP_NORESERVE
Do not reserve swap space for this mapping. When swap
space is reserved, one has the guarantee that it is
possible to modify the mapping. When swap space is not
reserved one might get SIGSEGV upon a write if no physical
memory is available. See also the discussion of the file
/proc/sys/vm/overcommit_memory in proc_sys_vm(5). Before
Linux 2.6, this flag had effect only for private writable
mappings.
MAP_POPULATE (since Linux 2.5.46)
Populate (prefault) page tables for a mapping. For a file
mapping, this causes read-ahead on the file. This will
help to reduce blocking on page faults later. The mmap()
call doesn't fail if the mapping cannot be populated (for
example, due to limitations on the number of mapped huge
pages when using MAP_HUGETLB). Support for MAP_POPULATE in
conjunction with private mappings was added in Linux
2.6.23.
MAP_STACK (since Linux 2.6.27)
Allocate the mapping at an address suitable for a process
or thread stack.
This flag is currently a no-op on Linux. However, by
employing this flag, applications can ensure that they
transparently obtain support if the flag is implemented in
the future. Thus, it is used in the glibc threading
implementation to allow for the fact that some
architectures may (later) require special treatment for
stack allocations. A further reason to employ this flag is
portability: MAP_STACK exists (and has an effect) on some
other systems (e.g., some of the BSDs).
MAP_SYNC (since Linux 4.15)
This flag is available only with the MAP_SHARED_VALIDATE
mapping type; mappings of type MAP_SHARED will silently
ignore this flag. This flag is supported only for files
supporting DAX (direct mapping of persistent memory). For
other files, creating a mapping with this flag results in
an EOPNOTSUPP error.
Shared file mappings with this flag provide the guarantee
that while some memory is mapped writable in the address
space of the process, it will be visible in the same file
at the same offset even after the system crashes or is
rebooted. In conjunction with the use of appropriate CPU
instructions, this provides users of such mappings with a
more efficient way of making data modifications persistent.
MAP_UNINITIALIZED (since Linux 2.6.33)
Don't clear anonymous pages. This flag is intended to
improve performance on embedded devices. This flag is
honored only if the kernel was configured with the
CONFIG_MMAP_ALLOW_UNINITIALIZED option. Because of the
security implications, that option is normally enabled only
on embedded devices (i.e., devices where one has complete
control of the contents of user memory).
Of the above flags, only MAP_FIXED is specified in POSIX.1-2001
and POSIX.1-2008. However, most systems also support
MAP_ANONYMOUS (or its synonym MAP_ANON).
munmap()
The munmap() system call deletes the mappings for the specified
address range, and causes further references to addresses within
the range to generate invalid memory references. The region is
also automatically unmapped when the process is terminated. On
the other hand, closing the file descriptor does not unmap the
region.
The address addr must be a multiple of the page size (but length
need not be). All pages containing a part of the indicated range
are unmapped, and subsequent references to these pages will
generate SIGSEGV. It is not an error if the indicated range does
not contain any mapped pages.
On success, mmap() returns a pointer to the mapped area. On
error, the value MAP_FAILED (that is, (void *) -1) is returned,
and errno is set to indicate the error.
On success, munmap() returns 0. On failure, it returns -1, and
errno is set to indicate the error (probably to EINVAL).
EACCES A file descriptor refers to a non-regular file. Or a file
mapping was requested, but fd is not open for reading. Or
MAP_SHARED was requested and PROT_WRITE is set, but fd is
not open in read/write (O_RDWR) mode. Or PROT_WRITE is
set, but the file is append-only.
EAGAIN The file has been locked, or too much memory has been
locked (see setrlimit(2)).
EBADF fd is not a valid file descriptor (and MAP_ANONYMOUS was
not set).
EEXIST MAP_FIXED_NOREPLACE was specified in flags, and the range
covered by addr and length clashes with an existing
mapping.
EINVAL We don't like addr, length, or offset (e.g., they are too
large, or not aligned on a page boundary).
EINVAL (since Linux 2.6.12) length was 0.
EINVAL flags contained none of MAP_PRIVATE, MAP_SHARED, or
MAP_SHARED_VALIDATE.
ENFILE The system-wide limit on the total number of open files has
been reached.
ENODEV The underlying filesystem of the specified file does not
support memory mapping.
ENOMEM No memory is available.
ENOMEM The process's maximum number of mappings would have been
exceeded. This error can also occur for munmap(), when
unmapping a region in the middle of an existing mapping,
since this results in two smaller mappings on either side
of the region being unmapped.
ENOMEM (since Linux 4.7) The process's RLIMIT_DATA limit,
described in getrlimit(2), would have been exceeded.
ENOMEM We don't like addr, because it exceeds the virtual address
space of the CPU.
EOVERFLOW
On 32-bit architecture together with the large file
extension (i.e., using 64-bit off_t): the number of pages
used for length plus number of pages used for offset would
overflow unsigned long (32 bits).
EPERM The prot argument asks for PROT_EXEC but the mapped area
belongs to a file on a filesystem that was mounted no-exec.
EPERM The operation was prevented by a file seal; see fcntl(2).
EPERM The MAP_HUGETLB flag was specified, but the caller was not
privileged (did not have the CAP_IPC_LOCK capability) and
is not a member of the hugetlb_shm_group group; see the
description of /proc/sys/vm/hugetlb_shm_group in
proc_sys_vm(5).
ETXTBSY
MAP_DENYWRITE was set but the object specified by fd is
open for writing.
Use of a mapped region can result in these signals:
SIGSEGV
Attempted write into a region mapped as read-only.
SIGBUS Attempted access to a page of the buffer that lies beyond
the end of the mapped file. For an explanation of the
treatment of the bytes in the page that corresponds to the
end of a mapped file that is not a multiple of the page
size, see NOTES.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ mmap(), munmap() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
On some hardware architectures (e.g., i386), PROT_WRITE implies
PROT_READ. It is architecture dependent whether PROT_READ implies
PROT_EXEC or not. Portable programs should always set PROT_EXEC
if they intend to execute code in the new mapping.
The portable way to create a mapping is to specify addr as 0
(NULL), and omit MAP_FIXED from flags. In this case, the system
chooses the address for the mapping; the address is chosen so as
not to conflict with any existing mapping, and will not be 0. If
the MAP_FIXED flag is specified, and addr is 0 (NULL), then the
mapped address will be 0 (NULL).
Certain flags constants are defined only if suitable feature test
macros are defined (possibly by default): _DEFAULT_SOURCE with
glibc 2.19 or later; or _BSD_SOURCE or _SVID_SOURCE in glibc 2.19
and earlier. (Employing _GNU_SOURCE also suffices, and requiring
that macro specifically would have been more logical, since these
flags are all Linux-specific.) The relevant flags are: MAP_32BIT,
MAP_ANONYMOUS (and the synonym MAP_ANON), MAP_DENYWRITE,
MAP_EXECUTABLE, MAP_FILE, MAP_GROWSDOWN, MAP_HUGETLB, MAP_LOCKED,
MAP_NONBLOCK, MAP_NORESERVE, MAP_POPULATE, and MAP_STACK.
C library/kernel differences
This page describes the interface provided by the glibc mmap()
wrapper function. Originally, this function invoked a system call
of the same name. Since Linux 2.4, that system call has been
superseded by mmap2(2), and nowadays the glibc mmap() wrapper
function invokes mmap2(2) with a suitably adjusted value for
offset.
POSIX.1-2008.
POSIX.1-2001, SVr4, 4.4BSD.
On POSIX systems on which mmap(), msync(2), and munmap() are
available, _POSIX_MAPPED_FILES is defined in <unistd.h> to a value
greater than 0. (See also sysconf(3).)
Memory mapped by mmap() is preserved across fork(2), with the same
attributes.
A file is mapped in multiples of the page size. For a file that
is not a multiple of the page size, the remaining bytes in the
partial page at the end of the mapping are zeroed when mapped, and
modifications to that region are not written out to the file. The
effect of changing the size of the underlying file of a mapping on
the pages that correspond to added or removed regions of the file
is unspecified.
An application can determine which pages of a mapping are
currently resident in the buffer/page cache using mincore(2).
Using MAP_FIXED safely
The only safe use for MAP_FIXED is where the address range
specified by addr and length was previously reserved using another
mapping; otherwise, the use of MAP_FIXED is hazardous because it
forcibly removes preexisting mappings, making it easy for a
multithreaded process to corrupt its own address space.
For example, suppose that thread A looks through /proc/pid/maps in
order to locate an unused address range that it can map using
MAP_FIXED, while thread B simultaneously acquires part or all of
that same address range. When thread A subsequently employs
mmap(MAP_FIXED), it will effectively clobber the mapping that
thread B created. In this scenario, thread B need not create a
mapping directly; simply making a library call that, internally,
uses dlopen(3) to load some other shared library, will suffice.
The dlopen(3) call will map the library into the process's address
space. Furthermore, almost any library call may be implemented in
a way that adds memory mappings to the address space, either with
this technique, or by simply allocating memory. Examples include
brk(2), malloc(3), pthread_create(3), and the PAM libraries
⟨http://www.linux-pam.org⟩.
Since Linux 4.17, a multithreaded program can use the
MAP_FIXED_NOREPLACE flag to avoid the hazard described above when
attempting to create a mapping at a fixed address that has not
been reserved by a preexisting mapping.
Timestamps changes for file-backed mappings
For file-backed mappings, the st_atime field for the mapped file
may be updated at any time between the mmap() and the
corresponding unmapping; the first reference to a mapped page will
update the field if it has not been already.
The st_ctime and st_mtime field for a file mapped with PROT_WRITE
and MAP_SHARED will be updated after a write to the mapped region,
and before a subsequent msync(2) with the MS_SYNC or MS_ASYNC
flag, if one occurs.
Huge page (Huge TLB) mappings
For mappings that employ huge pages, the requirements for the
arguments of mmap() and munmap() differ somewhat from the
requirements for mappings that use the native system page size.
For mmap(), offset must be a multiple of the underlying huge page
size. The system automatically aligns length to be a multiple of
the underlying huge page size.
For munmap(), addr, and length must both be a multiple of the
underlying huge page size.
Unlike typical malloc(3) implementations, mmap() does not prevent
creating objects larger than PTRDIFF_MAX. Objects that are larger
than PTRDIFF_MAX only work in limited ways in C (in particular,
pointer subtraction results in undefined behavior if the result
would be bigger than PTRDIFF_MAX). On top of that, GCC also
assumes that no object is bigger than PTRDIFF_MAX. PTRDIFF_MAX is
usually half of the address space size; so for 32-bit processes,
it is usually 0x7fffffff (almost 2 GiB).
On Linux, there are no guarantees like those suggested above under
MAP_NORESERVE. By default, any process can be killed at any
moment when the system runs out of memory.
Before Linux 2.6.7, the MAP_POPULATE flag has effect only if prot
is specified as PROT_NONE.
SUSv3 specifies that mmap() should fail if length is 0. However,
before Linux 2.6.12, mmap() succeeded in this case: no mapping was
created and the call returned addr. Since Linux 2.6.12, mmap()
fails with the error EINVAL for this case.
POSIX specifies that the system shall always zero fill any partial
page at the end of the object and that system will never write any
modification of the object beyond its end. On Linux, when you
write data to such partial page after the end of the object, the
data stays in the page cache even after the file is closed and
unmapped and even though the data is never written to the file
itself, subsequent mappings may see the modified content. In some
cases, this could be fixed by calling msync(2) before the unmap
takes place; however, this doesn't work on tmpfs(5) (for example,
when using the POSIX shared memory interface documented in
shm_overview(7)).
The following program prints part of the file specified in its
first command-line argument to standard output. The range of
bytes to be printed is specified via offset and length values in
the second and third command-line arguments. The program creates
a memory mapping of the required pages of the file and then uses
write(2) to output the desired bytes.
Program source
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
int
main(int argc, char *argv[])
{
int fd;
char *addr;
off_t offset, pa_offset;
size_t length;
ssize_t s;
struct stat sb;
if (argc < 3 || argc > 4) {
fprintf(stderr, "%s file offset [length]\n", argv[0]);
exit(EXIT_FAILURE);
}
fd = open(argv[1], O_RDONLY);
if (fd == -1)
handle_error("open");
if (fstat(fd, &sb) == -1) /* To obtain file size */
handle_error("fstat");
offset = atoi(argv[2]);
pa_offset = offset & ~(sysconf(_SC_PAGE_SIZE) - 1);
/* offset for mmap() must be page aligned */
if (offset >= sb.st_size) {
fprintf(stderr, "offset is past end of file\n");
exit(EXIT_FAILURE);
}
if (argc == 4) {
length = atoi(argv[3]);
if (offset + length > sb.st_size)
length = sb.st_size - offset;
/* Can't display bytes past end of file */
} else { /* No length arg ==> display to end of file */
length = sb.st_size - offset;
}
addr = mmap(NULL, length + offset - pa_offset, PROT_READ,
MAP_PRIVATE, fd, pa_offset);
if (addr == MAP_FAILED)
handle_error("mmap");
s = write(STDOUT_FILENO, addr + offset - pa_offset, length);
if (s != length) {
if (s == -1)
handle_error("write");
fprintf(stderr, "partial write");
exit(EXIT_FAILURE);
}
munmap(addr, length + offset - pa_offset);
close(fd);
exit(EXIT_SUCCESS);
}
ftruncate(2), getpagesize(2), memfd_create(2), mincore(2),
mlock(2), mmap2(2), mprotect(2), mremap(2), msync(2),
remap_file_pages(2), setrlimit(2), shmat(2), userfaultfd(2),
shm_open(3), shm_overview(7)
The descriptions of the following files in proc(5):
/proc/pid/maps, /proc/pid/map_files, and /proc/pid/smaps.
B.O. Gallmeister, POSIX.4, O'Reilly, pp. 128–129 and 389–391.
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-06-28 mmap(2)
Pages that refer to this page: memusage(1), alloc_hugepages(2), arch_prctl(2), clone(2), execve(2), fcntl_locking(2), F_GET_SEALS(2const), fork(2), futex(2), get_mempolicy(2), getpagesize(2), getrlimit(2), ioctl_userfaultfd(2), io_uring_register(2), io_uring_setup(2), madvise(2), mbind(2), memfd_create(2), memfd_secret(2), mincore(2), mlock(2), mmap2(2), mprotect(2), mremap(2), msync(2), open(2), perf_event_open(2), personality(2), posix_fadvise(2), PR_SET_MM_ARG_START(2const), PR_SET_MM_START_CODE(2const), PR_SET_TAGGED_ADDR_CTRL(2const), readahead(2), remap_file_pages(2), seccomp(2), sendfile(2), set_mempolicy(2), shmget(2), shmop(2), statx(2), syscalls(2), UFFDIO_API(2const), uselib(2), userfaultfd(2), vfork(2), avc_init(3), avc_open(3), cap_launch(3), fopen(3), io_uring_queue_exit(3), io_uring_queue_init(3), io_uring_queue_init_mem(3), io_uring_queue_init_params(3), mallinfo(3), malloc(3), malloc_stats(3), mallopt(3), numa(3), off_t(3type), pthread_attr_setguardsize(3), pthread_attr_setstack(3), selinux_status_open(3), sem_init(3), shm_open(3), core(5), proc(5), proc_meminfo(5), proc_pid_map_files(5), proc_pid_maps(5), proc_sys_kernel(5), proc_sys_vm(5), systemd.exec(5), tmpfs(5), capabilities(7), fanotify(7), file-hierarchy(7), futex(7), inode(7), inotify(7), io_uring(7), pkeys(7), shm_overview(7), spufs(7), ld.so(8), netsniff-ng(8), setarch(8), trafgen(8), xfs_io(8)