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* [PATCH] docs: cgroup: mm: Document why inactive_X + active_X may not equal X
@ 2019-11-11 14:49 Chris Down
  2019-11-11 14:53 ` Michal Hocko
  0 siblings, 1 reply; 2+ messages in thread
From: Chris Down @ 2019-11-11 14:49 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Johannes Weiner, Tejun Heo, Roman Gushchin, Michal Hocko,
	linux-kernel, cgroups, linux-mm, kernel-team

This has confused a significant number of people using cgroups inside
Facebook, and some of those outside as well judging by posts like
this[0] (although it's not a problem unique to cgroup v2). If shmem
handling in particular becomes more coherent at some point in the future
-- although that seems unlikely now -- we can change the wording here.


Signed-off-by: Chris Down <>
Cc: Andrew Morton <>
Cc: Johannes Weiner <>
Cc: Tejun Heo <>
Cc: Roman Gushchin <>
Cc: Michal Hocko <>
 Documentation/admin-guide/cgroup-v2.rst | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 0704552ed94f..0636bcb60b5a 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1289,7 +1289,12 @@ PAGE_SIZE multiple when read back.
 	  inactive_anon, active_anon, inactive_file, active_file, unevictable
 		Amount of memory, swap-backed and filesystem-backed,
 		on the internal memory management lists used by the
-		page reclaim algorithm
+		page reclaim algorithm.
+		As these represent internal list state (eg. shmem pages are on anon
+		memory management lists), inactive_foo + active_foo may not be equal to
+		the value for the foo counter, since the foo counter is type-based, not
+		list-based.
 		Part of "slab" that might be reclaimed, such as

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2019-11-11 14:49 [PATCH] docs: cgroup: mm: Document why inactive_X + active_X may not equal X Chris Down
2019-11-11 14:53 ` Michal Hocko

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