Commit 8cee852e authored by Jerome Marchand's avatar Jerome Marchand Committed by Linus Torvalds

mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status

There are several shortcomings with the accounting of shared memory
(SysV shm, shared anonymous mapping, mapping of a tmpfs file).  The
values in /proc/<pid>/status and <...>/statm don't allow to distinguish
between shmem memory and a shared mapping to a regular file, even though
theirs implication on memory usage are quite different: during reclaim,
file mapping can be dropped or written back on disk, while shmem needs a
place in swap.

Also, to distinguish the memory occupied by anonymous and file mappings,
one has to read the /proc/pid/statm file, which has a field for the file
mappings (again, including shmem) and total memory occupied by these
mappings (i.e.  equivalent to VmRSS in the <...>/status file.  Getting
the value for anonymous mappings only is thus not exactly user-friendly
(the statm file is intended to be rather efficiently machine-readable).

To address both of these shortcomings, this patch adds a breakdown of
VmRSS in /proc/<pid>/status via new fields RssAnon, RssFile and
RssShmem, making use of the previous preparatory patch.  These fields
tell the user the memory occupied by private anonymous pages, mapped
regular files and shmem, respectively.  Other existing fields in /status
and /statm files are left without change.  The /statm file can be
extended in the future, if there's a need for that.

Example (part of) /proc/pid/status output including the new Rss* fields:

VmPeak:  2001008 kB
VmSize:  2001004 kB
VmLck:         0 kB
VmPin:         0 kB
VmHWM:      5108 kB
VmRSS:      5108 kB
RssAnon:              92 kB
RssFile:            1324 kB
RssShmem:           3692 kB
VmData:      192 kB
VmStk:       136 kB
VmExe:         4 kB
VmLib:      1784 kB
VmPTE:      3928 kB
VmPMD:        20 kB
VmSwap:        0 kB
HugetlbPages:          0 kB

[ forward-porting, tweak changelog]
Signed-off-by: default avatarJerome Marchand <>
Signed-off-by: default avatarVlastimil Babka <>
Acked-by: default avatarKonstantin Khlebnikov <>
Acked-by: default avatarMichal Hocko <>
Acked-by: default avatarHugh Dickins <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent eca56ff9
......@@ -169,6 +169,9 @@ read the file /proc/PID/status:
VmLck: 0 kB
VmHWM: 476 kB
VmRSS: 476 kB
RssAnon: 352 kB
RssFile: 120 kB
RssShmem: 4 kB
VmData: 156 kB
VmStk: 88 kB
VmExe: 68 kB
......@@ -231,7 +234,12 @@ Table 1-2: Contents of the status files (as of 4.1)
VmSize total program size
VmLck locked memory size
VmHWM peak resident set size ("high water mark")
VmRSS size of memory portions
VmRSS size of memory portions. It contains the three
following parts (VmRSS = RssAnon + RssFile + RssShmem)
RssAnon size of resident anonymous memory
RssFile size of resident file mappings
RssShmem size of resident shmem memory (includes SysV shm,
mapping of tmpfs and shared anonymous mappings)
VmData size of data, stack, and text segments
VmStk size of data, stack, and text segments
VmExe size of text segment
......@@ -266,7 +274,8 @@ Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
Field Content
size total program size (pages) (same as VmSize in status)
resident size of memory portions (pages) (same as VmRSS in status)
shared number of pages that are shared (i.e. backed by a file)
shared number of pages that are shared (i.e. backed by a file, same
as RssFile+RssShmem in status)
trs number of pages that are 'code' (not including libs; broken,
includes data segment)
lrs number of pages of library (always 0 on 2.6)
......@@ -23,9 +23,13 @@
void task_mem(struct seq_file *m, struct mm_struct *mm)
unsigned long data, text, lib, swap, ptes, pmds;
unsigned long data, text, lib, swap, ptes, pmds, anon, file, shmem;
unsigned long hiwater_vm, total_vm, hiwater_rss, total_rss;
anon = get_mm_counter(mm, MM_ANONPAGES);
file = get_mm_counter(mm, MM_FILEPAGES);
shmem = get_mm_counter(mm, MM_SHMEMPAGES);
* Note: to minimize their overhead, mm maintains hiwater_vm and
* hiwater_rss only when about to *lower* total_vm or rss. Any
......@@ -36,7 +40,7 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
hiwater_vm = total_vm = mm->total_vm;
if (hiwater_vm < mm->hiwater_vm)
hiwater_vm = mm->hiwater_vm;
hiwater_rss = total_rss = get_mm_rss(mm);
hiwater_rss = total_rss = anon + file + shmem;
if (hiwater_rss < mm->hiwater_rss)
hiwater_rss = mm->hiwater_rss;
......@@ -53,6 +57,9 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
"VmPin:\t%8lu kB\n"
"VmHWM:\t%8lu kB\n"
"VmRSS:\t%8lu kB\n"
"RssAnon:\t%8lu kB\n"
"RssFile:\t%8lu kB\n"
"RssShmem:\t%8lu kB\n"
"VmData:\t%8lu kB\n"
"VmStk:\t%8lu kB\n"
"VmExe:\t%8lu kB\n"
......@@ -66,6 +73,9 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
mm->pinned_vm << (PAGE_SHIFT-10),
hiwater_rss << (PAGE_SHIFT-10),
total_rss << (PAGE_SHIFT-10),
anon << (PAGE_SHIFT-10),
file << (PAGE_SHIFT-10),
shmem << (PAGE_SHIFT-10),
data << (PAGE_SHIFT-10),
mm->stack_vm << (PAGE_SHIFT-10), text, lib,
ptes >> 10,
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