path: root/Documentation/filesystems/proc.txt
diff options
Diffstat (limited to 'Documentation/filesystems/proc.txt')
1 files changed, 129 insertions, 9 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index fb0a6ae..fd8d0d5 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -41,6 +41,7 @@ Table of Contents
3.5 /proc/<pid>/mountinfo - Information about mounts
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
3.7 /proc/<pid>/task/<tid>/children - Information about task children
+ 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
4 Configuring procfs
4.1 Mount options
@@ -142,7 +143,7 @@ Table 1-1: Process specific entries in /proc
pagemap Page table
stack Report full stack trace, enable via CONFIG_STACKTRACE
smaps a extension based on maps, showing the memory consumption of
- each mapping
+ each mapping and flags associated with it
For example, to get the status information of a process, all you have to do is
@@ -181,6 +182,7 @@ read the file /proc/PID/status:
CapPrm: 0000000000000000
CapEff: 0000000000000000
CapBnd: ffffffffffffffff
+ Seccomp: 0
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 1
@@ -237,6 +239,7 @@ Table 1-2: Contents of the status files (as of 2.6.30-rc7)
CapPrm bitmap of permitted capabilities
CapEff bitmap of effective capabilities
CapBnd bitmap of capabilities bounding set
+ Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
Cpus_allowed mask of CPUs on which this process may run
Cpus_allowed_list Same as previous, but in "list format"
Mems_allowed mask of memory nodes allowed to this process
@@ -415,8 +418,9 @@ Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 374 kB
+VmFlags: rd ex mr mw me de
-The first of these lines shows the same information as is displayed for the
+the first of these lines shows the same information as is displayed for the
mapping in /proc/PID/maps. The remaining lines show the size of the mapping
(size), the amount of the mapping that is currently resident in RAM (RSS), the
process' proportional share of this mapping (PSS), the number of clean and
@@ -430,6 +434,41 @@ and a page is modified, the file page is replaced by a private anonymous copy.
"Swap" shows how much would-be-anonymous memory is also used, but out on
+"VmFlags" field deserves a separate description. This member represents the kernel
+flags associated with the particular virtual memory area in two letter encoded
+manner. The codes are the following:
+ rd - readable
+ wr - writeable
+ ex - executable
+ sh - shared
+ mr - may read
+ mw - may write
+ me - may execute
+ ms - may share
+ gd - stack segment growns 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
+ nl - non-linear mapping
+ ar - architecture specific flag
+ dd - do not include area into core dump
+ mm - mixed map area
+ hg - huge page advise flag
+ nh - no-huge page advise flag
+ mg - mergable advise flag
+Note that there is no guarantee that every flag and associated mnemonic will
+be present in all further kernel releases. Things get changed, the flags may
+be vanished or the reverse -- new added.
This file is only present if the CONFIG_MMU kernel configuration option is
@@ -1367,16 +1406,10 @@ be used to tune the badness score. Its acceptable values range from -16
(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
scaled linearly with /proc/<pid>/oom_score_adj.
-Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the
-other with its scaled value.
The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
-NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see
Caveat: when a parent task is selected, the oom killer will sacrifice any first
generation children with separate address spaces instead, if possible. This
avoids servers and important system daemons from being killed and loses the
@@ -1387,7 +1420,7 @@ minimal amount of work.
This file can be used to check the current score used by the oom-killer is for
-any given <pid>. Use it together with /proc/<pid>/oom_adj to tune which
+any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
process should be killed in an out-of-memory situation.
@@ -1601,6 +1634,93 @@ pids, so one need to either stop or freeze processes being inspected
if precise results are needed.
+3.7 /proc/<pid>/fdinfo/<fd> - Information about opened file
+This file provides information associated with an opened file. The regular
+files have at least two fields -- 'pos' and 'flags'. The 'pos' represents
+the current offset of the opened file in decimal form [see lseek(2) for
+details] and 'flags' denotes the octal O_xxx mask the file has been
+created with [see open(2) for details].
+A typical output is
+ pos: 0
+ flags: 0100002
+The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
+pair provide additional information particular to the objects they represent.
+ Eventfd files
+ ~~~~~~~~~~~~~
+ pos: 0
+ flags: 04002
+ eventfd-count: 5a
+ where 'eventfd-count' is hex value of a counter.
+ Signalfd files
+ ~~~~~~~~~~~~~~
+ pos: 0
+ flags: 04002
+ sigmask: 0000000000000200
+ where 'sigmask' is hex value of the signal mask associated
+ with a file.
+ Epoll files
+ ~~~~~~~~~~~
+ pos: 0
+ flags: 02
+ tfd: 5 events: 1d data: ffffffffffffffff
+ where 'tfd' is a target file descriptor number in decimal form,
+ 'events' is events mask being watched and the 'data' is data
+ associated with a target [see epoll(7) for more details].
+ Fsnotify files
+ ~~~~~~~~~~~~~~
+ For inotify files the format is the following
+ pos: 0
+ flags: 02000000
+ inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
+ where 'wd' is a watch descriptor in decimal form, ie a target file
+ descriptor number, 'ino' and 'sdev' are inode and device where the
+ target file resides and the 'mask' is the mask of events, all in hex
+ form [see inotify(7) for more details].
+ If the kernel was built with exportfs support, the path to the target
+ file is encoded as a file handle. The file handle is provided by three
+ fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
+ format.
+ If the kernel is built without exportfs support the file handle won't be
+ printed out.
+ If there is no inotify mark attached yet the 'inotify' line will be omitted.
+ For fanotify files the format is
+ pos: 0
+ flags: 02
+ fanotify flags:10 event-flags:0
+ fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
+ fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
+ where fanotify 'flags' and 'event-flags' are values used in fanotify_init
+ call, 'mnt_id' is the mount point identifier, 'mflags' is the value of
+ flags associated with mark which are tracked separately from events
+ mask. 'ino', 'sdev' are target inode and device, 'mask' is the events
+ mask and 'ignored_mask' is the mask of events which are to be ignored.
+ All in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
+ does provide information about flags and mask used in fanotify_mark
+ call [see fsnotify manpage for details].
+ While the first three lines are mandatory and always printed, the rest is
+ optional and may be omitted if no marks created yet.
Configuring procfs