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Swap accounting looks busted #60

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stgraber opened this issue Dec 14, 2015 · 3 comments
Closed

Swap accounting looks busted #60

stgraber opened this issue Dec 14, 2015 · 3 comments

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@stgraber
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root@blah:~# free -m
             total       used       free     shared    buffers     cached
Mem:         11912         58      11853         31          0         49
-/+ buffers/cache:          9      11903
Swap:   8796093010295          0 8796093010295
root@blah:~#

Host value is 6GB of swap, container has no swap limit.
@hallyn
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hallyn commented Dec 17, 2015 via email

@nehaljwani
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Not sure, if I am having the same problem, but:

[root@test ~]# head /sys/fs/cgroup/memory/lxc/test/memory.memsw.*
==> /sys/fs/cgroup/memory/lxc/test/memory.memsw.failcnt <==
0

==> /sys/fs/cgroup/memory/lxc/test/memory.memsw.limit_in_bytes <==
268435456

==> /sys/fs/cgroup/memory/lxc/test/memory.memsw.max_usage_in_bytes <==
15876096

==> /sys/fs/cgroup/memory/lxc/test/memory.memsw.usage_in_bytes <==
15785984
[root@test ~]# free -m
             total       used       free     shared    buffers     cached
Mem:           256         15        240         33          0         10
-/+ buffers/cache:          4        251 
Swap:        24199        104      24095

Host has 24199MB of swap, and:

ibm1:~/wani/lxcfs [539]# lxc-info -c lxc.cgroup.memory.limit_in_bytes -n test
lxc.cgroup.memory.limit_in_bytes = 256M

ibm1:~/wani/lxcfs [540]# lxc-info -c lxc.cgroup.memory.memsw.limit_in_bytes -n test
lxc.cgroup.memory.memsw.limit_in_bytes = 256M

If I revert the patch a2de34b, then the problem goes away for me.

nehaljwani added a commit to nehaljwani/lxcfs that referenced this issue Dec 18, 2015
@nehaljwani
Fix busted swap usage
6e5006b 
When no limit is specified using lxc.cgroup.memory.memsw.limit_in_bytes,
overflow occurs while calculating Swap{Total,Free}. Commit a2de34b tried
to fix this, but introduced another bug, wherein if
memory.memsw.limit_in_bytes >= memory.limit_in_bytes, then Swap{Total,Free}
are not shown as expected.

This patch assumes that if memory.memsw.limit_in_bytes is not set, then
/sys/fs/cgroup/memory/lxc/${CT_NAME}/memory.memsw.limit_in_bytes will have
the default value = LONG_MAX based on:
https://github.com/torvalds/linux/blob/v4.3/mm/memcontrol.c#L4037
https://github.com/torvalds/linux/blob/v4.3/mm/memcontrol.c#L2893
https://github.com/torvalds/linux/blob/v4.3/include/linux/page_counter.h#L21

Fixes lxc#60

Signed-off-by: Nehal J Wani <nehaljw.kkd1@gmail.com>
@nehaljwani nehaljwani mentioned this issue Dec 18, 2015
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nehaljwani added a commit to nehaljwani/lxcfs that referenced this issue Jan 8, 2016
@nehaljwani
Fix busted swap usage
3e0faa0 
When no limit is specified using lxc.cgroup.memory.memsw.limit_in_bytes,
overflow occurs while calculating Swap{Total,Free}. Commit a2de34b tried
to fix this, but introduced another bug, wherein if
memory.memsw.limit_in_bytes >= memory.limit_in_bytes, then Swap{Total,Free}
are not shown as expected.

This patch assumes that if memory.memsw.limit_in_bytes is not set, then
/sys/fs/cgroup/memory/lxc/${CT_NAME}/memory.memsw.limit_in_bytes will have
the default value = LONG_MAX based on:
https://github.com/torvalds/linux/blob/v4.3/mm/memcontrol.c#L4037
https://github.com/torvalds/linux/blob/v4.3/mm/memcontrol.c#L2893
https://github.com/torvalds/linux/blob/v4.3/include/linux/page_counter.h#L21

Fixes lxc#60

Signed-off-by: Nehal J Wani <nehaljw.kkd1@gmail.com>
@hallyn
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hallyn commented Jan 12, 2016

@stgraber

I will assume this is fixed by the commit i referenced earlier.

@hallyn hallyn closed this as completed Jan 12, 2016
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Fix busted swap usage nehaljwani/lxcfs
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@hallyn @nehaljwani @stgraber