Revert: #935Fixes: #946
I can reproduce #946 on some machines, the problem is on
some machines, it could be very fast that modify time
of `memory.kmem.limit_in_bytes` could be the same as
before it's modified.
And now we'll call `SetKernelMemory` twice on container
creation which cause the second time failure.
Revert this before we find a better solution.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Kernel memory cannot be set in these circumstances (before kernel 4.6):
1. kernel memory is not initialized, and there are tasks in cgroup
2. kernel memory is not initialized, and use_hierarchy is enabled,
and there are sub-cgroups
While we don't need to cover case 2 because when we set kernel
memory in runC, it's either:
- in Apply phase when we create the container, and in this case,
set kernel memory would definitely be valid;
- or in update operation, and in this case, there would be tasks
in cgroup, we only need to check if kernel memory is initialized
or not.
Even if we want to check use_hierarchy, we need to check sub-cgroups
as well, but for here, we can just leave it aside.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
When swap memory is unsupported, Docker will set
cgroup.Resources.MemorySwap as -1.
Fixes: https://github.com/docker/docker/pull/21937
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Currently, if we start a container with:
`docker run -ti --name foo --memory 300M --memory-swap 500M busybox sh`
Then we want to update it with:
`docker update --memory 600M --memory-swap 800M foo`
It'll get error because we can't set memory to 600M with
the 500M limit of swap memory.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
This prior fix to set "-1" explicitly was lost, and it is simpler to use
the same pointer type from the OCI spec to handle nil pointer == -1 ==
unset case.
Also, as a nearly humorous aside, there was a test for MemorySwappiness
that was actually setting Memory, and it was passing because of this
bug (as it was always setting everyone's MemorySwappiness to zero!)
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Modify the memory cgroup code such that kmem is not managed by Set(), in
order to allow updating of memory constraints for containers by Docker.
This also removes the need to make memory a special case cgroup.
Signed-off-by: Aleksa Sarai <asarai@suse.com>
Apply and Set are two separate operations, and it doesn't make sense to
group the two together (especially considering that the bootstrap
process is added to the cgroup as well). The only exception to this is
the memory cgroup, which requires the configuration to be set before
processes can join.
One of the weird cases to deal with is systemd. Systemd sets some of the
cgroup configuration options, but not all of them. Because memory is a
special case, we need to explicitly set memory in the systemd Apply().
Otherwise, the rest can be safely re-applied in .Set() as usual.
Signed-off-by: Aleksa Sarai <asarai@suse.com>
Apply and Set are two separate operations, and it doesn't make sense to
group the two together (especially considering that the bootstrap
process is added to the cgroup as well). The only exception to this is
the memory cgroup, which requires the configuration to be set before
processes can join.
Signed-off-by: Aleksa Sarai <asarai@suse.com>
This allows us to distinguish cases where a container
needs to just join the paths or also additionally
set cgroups settings. This will help in implementing
cgroupsPath support in the spec.
Signed-off-by: Mrunal Patel <mrunalp@gmail.com>
The former cgroup entry is confusing, separate it to parent
and name.
Rename entry `c` to `config`.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
'parent' function is confusing with parent cgroup, it's actually
parent path, so rename it to parentPath.
The name 'data' is too common to be identified, rename it to cgroupData
which is exactly what it is.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
We have a rule that for optional cgroups, don't fail if some
of them are not mounted, but we want it fail hard when a
user specifies an option and we are unable to fulfill the
request.
Memory cgroup should also follow this rule.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
TL;DR: check for IsExist(err) after a failed MkdirAll() is both
redundant and wrong -- so two reasons to remove it.
Quoting MkdirAll documentation:
> MkdirAll creates a directory named path, along with any necessary
> parents, and returns nil, or else returns an error. If path
> is already a directory, MkdirAll does nothing and returns nil.
This means two things:
1. If a directory to be created already exists, no error is
returned.
2. If the error returned is IsExist (EEXIST), it means there exists
a non-directory with the same name as MkdirAll need to use for
directory. Example: we want to MkdirAll("a/b"), but file "a"
(or "a/b") already exists, so MkdirAll fails.
The above is a theory, based on quoted documentation and my UNIX
knowledge.
3. In practice, though, current MkdirAll implementation [1] returns
ENOTDIR in most of cases described in #2, with the exception when
there is a race between MkdirAll and someone else creating the
last component of MkdirAll argument as a file. In this very case
MkdirAll() will indeed return EEXIST.
Because of #1, IsExist check after MkdirAll is not needed.
Because of #2 and #3, ignoring IsExist error is just plain wrong,
as directory we require is not created. It's cleaner to report
the error now.
Note this error is all over the tree, I guess due to copy-paste,
or trying to follow the same usage pattern as for Mkdir(),
or some not quite correct examples on the Internet.
[1] https://github.com/golang/go/blob/f9ed2f75/src/os/path.go
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
In some older kernels setting swappiness fails. This happens even
when nobody tries to configure swappiness from docker UI because
we would still get some default value from host config.
With this we treat -1 value as default value (set implicitly) and skip
the enforcement of swappiness.
However from the docker UI setting an invalid value anything other than
0-100 including -1 should fail. This patch enables that fix in docker UI.
without this fix container creation with invalid value succeeds with a
default value (60) which in incorrect.
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Michael Crosby
Buddha Prakash
Qiang Huang
Vishnu kannan
Kenfe-Mickael Laventure
Aleksa Sarai
Phil Estes
Aleksa Sarai
Mrunal Patel
Mrunal Patel
Shijiang Wei
Kir Kolyshkin
Raghavendra K T