proc_pid_smaps(5)             File Formats Manual            proc_pid_smaps(5)

NAME
       /proc/pid/smaps - XXX: What does 's' in "smaps" stand for?

DESCRIPTION
       /proc/pid/smaps (since Linux 2.6.14)
              This file shows memory consumption for each of the process's
              mappings.  (The pmap(1) command displays similar information, in
              a form that may be easier for parsing.)  For each mapping there
              is a series of lines such as the following:

                  00400000-0048a000 r-xp 00000000 fd:03 960637       /bin/bash
                  Size:                552 kB
                  Rss:                 460 kB
                  Pss:                 100 kB
                  Shared_Clean:        452 kB
                  Shared_Dirty:          0 kB
                  Private_Clean:         8 kB
                  Private_Dirty:         0 kB
                  Referenced:          460 kB
                  Anonymous:             0 kB
                  AnonHugePages:         0 kB
                  ShmemHugePages:        0 kB
                  ShmemPmdMapped:        0 kB
                  Swap:                  0 kB
                  KernelPageSize:        4 kB
                  MMUPageSize:           4 kB
                  Locked:                0 kB
                  ProtectionKey:         0
                  VmFlags: rd ex mr mw me dw

              The first of these lines shows the same information as is
              displayed for the mapping in /proc/pid/maps.  The following
              lines show the size of the mapping, the amount of the mapping
              that is currently resident in RAM ("Rss"), the process's
              proportional share of this mapping ("Pss"), the number of clean
              and dirty shared pages in the mapping, and the number of clean
              and dirty private pages in the mapping.  "Referenced" indicates
              the amount of memory currently marked as referenced or accessed.
              "Anonymous" shows the amount of memory that does not belong to
              any file.  "Swap" shows how much would-be-anonymous memory is
              also used, but out on swap.

              The "KernelPageSize" line (available since Linux 2.6.29) is the
              page size used by the kernel to back the virtual memory area.
              This matches the size used by the MMU in the majority of cases.
              However, one counter-example occurs on PPC64 kernels whereby a
              kernel using 64 kB as a base page size may still use 4 kB pages
              for the MMU on older processors.  To distinguish the two
              attributes, the "MMUPageSize" line (also available since Linux
              2.6.29) reports the page size used by the MMU.

              The "Locked" indicates whether the mapping is locked in memory
              or not.

              The "ProtectionKey" line (available since Linux 4.9, on x86
              only) contains the memory protection key (see pkeys(7))
              associated with the virtual memory area.  This entry is present
              only if the kernel was built with the
              CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS configuration option
              (since Linux 4.6).

              The "VmFlags" line (available since Linux 3.8) represents the
              kernel flags associated with the virtual memory area, encoded
              using the following two-letter codes:

                     rd   -   readable
                     wr   -   writable
                     ex   -   executable
                     sh   -   shared
                     mr   -   may read
                     mw   -   may write
                     me   -   may execute
                     ms   -   may share
                     gd   -   stack segment grows down
                     pf   -   pure PFN range
                     dw   -   disabled write to the mapped file
                     lo   -   pages are locked in memory
                     io   -   memory mapped I/O area
                     sr   -   sequential read advise provided
                     rr   -   random read advise provided
                     dc   -   do not copy area on fork
                     de   -   do not expand area on remapping
                     ac   -   area is accountable
                     nr   -   swap space is not reserved for the area
                     ht   -   area uses huge tlb pages
                     sf   -   perform synchronous page faults (since Linux 4.15)
                     nl   -   non-linear mapping (removed in Linux 4.0)
                     ar   -   architecture specific flag
                     wf   -   wipe on fork (since Linux 4.14)
                     dd   -   do not include area into core dump
                     sd   -   soft-dirty flag (since Linux 3.13)
                     mm   -   mixed map area
                     hg   -   huge page advise flag
                     nh   -   no-huge page advise flag
                     mg   -   mergeable advise flag
                     um   -   userfaultfd missing pages tracking (since Linux 4.3)
                     uw   -   userfaultfd wprotect pages tracking (since Linux 4.3)

              The /proc/pid/smaps file is present only if the
              CONFIG_PROC_PAGE_MONITOR kernel configuration option is enabled.

SEE ALSO
       proc(5)

Linux man-pages 6.9.1             2024-05-02                 proc_pid_smaps(5)