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Merge pull request #16559 from benzea/benzea/memory-recursiveprot

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mount-setup: Enable memory_recursiveprot for cgroup2
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Zbigniew Jędrzejewski-Szmek 2020-08-20 13:05:07 +02:00 committed by GitHub
commit ec673ad4ab
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2 changed files with 25 additions and 34 deletions
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57
man/systemd.resource-control.xml
View File

@ -261,53 +261,42 @@
</varlistentry>
<varlistentry>
<term><varname>MemoryMin=<replaceable>bytes</replaceable></varname></term>
<term><varname>MemoryMin=<replaceable>bytes</replaceable></varname>, <varname>MemoryLow=<replaceable>bytes</replaceable></varname></term>
<listitem>
<para>Specify the memory usage protection of the executed processes in this unit. If the memory usages of
this unit and all its ancestors are below their minimum boundaries, this unit's memory won't be reclaimed.</para>
<para>Specify the memory usage protection of the executed processes in this unit.
When reclaiming memory, the unit is treated as if it was using less memory resulting in memory
to be preferentially reclaimed from unprotected units.
Using <varname>MemoryLow=</varname> results in a weaker protection where memory may still
be reclaimed to avoid invoking the OOM killer in case there is no other reclaimable memory.</para>
<para>
For a protection to be effective, it is generally required to set a corresponding
allocation on all ancestors, which is then distributed between children
(with the exception of the root slice).
Any <varname>MemoryMin=</varname> or <varname>MemoryLow=</varname> allocation that is not
explicitly distributed to specific children is used to create a shared protection for all children.
As this is a shared protection, the children will freely compete for the memory.</para>
<para>Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is
parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a
percentage value may be specified, which is taken relative to the installed physical memory on the
system. If assigned the special value <literal>infinity</literal>, all available memory is protected, which may be
useful in order to always inherit all of the protection afforded by ancestors.
This controls the <literal>memory.min</literal> control group attribute. For details about this
control group attribute, see <ulink
This controls the <literal>memory.min</literal> or <literal>memory.low</literal> control group attribute.
For details about this control group attribute, see <ulink
url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para>
<para>This setting is supported only if the unified control group hierarchy is used and disables
<varname>MemoryLimit=</varname>.</para>
<para>Units may have their children use a default <literal>memory.min</literal> value by specifying
<varname>DefaultMemoryMin=</varname>, which has the same semantics as <varname>MemoryMin=</varname>. This setting
does not affect <literal>memory.min</literal> in the unit itself.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>MemoryLow=<replaceable>bytes</replaceable></varname></term>
<listitem>
<para>Specify the best-effort memory usage protection of the executed processes in this unit. If the memory
usages of this unit and all its ancestors are below their low boundaries, this unit's memory won't be
reclaimed as long as memory can be reclaimed from unprotected units.</para>
<para>Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is
parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a
percentage value may be specified, which is taken relative to the installed physical memory on the
system. If assigned the special value <literal>infinity</literal>, all available memory is protected, which may be
useful in order to always inherit all of the protection afforded by ancestors.
This controls the <literal>memory.low</literal> control group attribute. For details about this
control group attribute, see <ulink
url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para>
<para>This setting is supported only if the unified control group hierarchy is used and disables
<varname>MemoryLimit=</varname>.</para>
<para>Units may have their children use a default <literal>memory.low</literal> value by specifying
<varname>DefaultMemoryLow=</varname>, which has the same semantics as <varname>MemoryLow=</varname>. This setting
does not affect <literal>memory.low</literal> in the unit itself.</para>
<para>Units may have their children use a default <literal>memory.min</literal> or
<literal>memory.low</literal> value by specifying <varname>DefaultMemoryMin=</varname> or
<varname>DefaultMemoryLow=</varname>, which has the same semantics as
<varname>MemoryMin=<replaceable> and <varname>MemoryLow=<replaceable>.
This setting does not affect <literal>memory.min</literal> or <literal>memory.low</literal>
in the unit itself.
Using it to set a default child allocation is only useful on kernels older than 5.7,
which do not support the <literal>memory_recursiveprot</literal> cgroup2 mount option.</para>
</listitem>
</varlistentry>

2
src/core/mount-setup.c
View File

@ -85,6 +85,8 @@ static const MountPoint mount_table[] = {
#endif
{ "tmpfs", "/run", "tmpfs", "mode=755" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME,
NULL, MNT_FATAL|MNT_IN_CONTAINER },
{ "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate,memory_recursiveprot", MS_NOSUID|MS_NOEXEC|MS_NODEV,
cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE },
{ "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate", MS_NOSUID|MS_NOEXEC|MS_NODEV,
cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE },
{ "cgroup2", "/sys/fs/cgroup", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,