Documentation/memcg: update kmem limit doc as codes behavior
The restriction of kmem setting is not there anymore because the
accounting is enabled by default even in the cgroup v1 - see
b313aeee25
("mm: memcontrol: enable kmem accounting for all
cgroups in the legacy hierarchy").
Update docs accordingly.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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1 changed files with 3 additions and 11 deletions
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@ -280,17 +280,9 @@ the amount of kernel memory used by the system. Kernel memory is fundamentally
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different than user memory, since it can't be swapped out, which makes it
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different than user memory, since it can't be swapped out, which makes it
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possible to DoS the system by consuming too much of this precious resource.
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possible to DoS the system by consuming too much of this precious resource.
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Kernel memory won't be accounted at all until limit on a group is set. This
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Kernel memory accounting is enabled for all memory cgroups by default. But
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allows for existing setups to continue working without disruption. The limit
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it can be disabled system-wide by passing cgroup.memory=nokmem to the kernel
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cannot be set if the cgroup have children, or if there are already tasks in the
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at boot time. In this case, kernel memory will not be accounted at all.
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cgroup. Attempting to set the limit under those conditions will return -EBUSY.
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When use_hierarchy == 1 and a group is accounted, its children will
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automatically be accounted regardless of their limit value.
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After a group is first limited, it will be kept being accounted until it
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is removed. The memory limitation itself, can of course be removed by writing
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-1 to memory.kmem.limit_in_bytes. In this case, kmem will be accounted, but not
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limited.
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Kernel memory limits are not imposed for the root cgroup. Usage for the root
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Kernel memory limits are not imposed for the root cgroup. Usage for the root
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cgroup may or may not be accounted. The memory used is accumulated into
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cgroup may or may not be accounted. The memory used is accumulated into
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