docs: cgroup-v1: add missing code-block tags

Hugetlb.rst lacks two code-block tags, causing a formatting issue.

Signed-off-by: Xinyu Li <lixinyu20s@ict.ac.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>

hugetlb: add hugetlb.*.numa_stat file

For hugetlb backed jobs/VMs it's critical to understand the numa
information for the memory backing these jobs to deliver optimal
performance.

Currently this technically can be queried from /proc/self/numa_maps, but
there are significant issues with that. Namely:

1. Memory can be mapped or unmapped.

2. numa_maps are per process and need to be aggregated across all
processes in the cgroup. For shared memory this is more involved as
the userspace needs to make sure it doesn't double count shared
mappings.

3. I believe querying numa_maps needs to hold the mmap_lock which adds
to the contention on this lock.

For these reasons I propose simply adding hugetlb.*.numa_stat file,
which shows the numa information of the cgroup similarly to
memory.numa_stat.

On cgroup-v2:
cat /sys/fs/cgroup/unified/test/hugetlb.2MB.numa_stat
total=2097152 N0=2097152 N1=0

On cgroup-v1:
cat /sys/fs/cgroup/hugetlb/test/hugetlb.2MB.numa_stat
total=2097152 N0=2097152 N1=0
hierarichal_total=2097152 N0=2097152 N1=0

This patch was tested manually by allocating hugetlb memory and querying
the hugetlb.*.numa_stat file of the cgroup and its parents.

[colin.i.king@googlemail.com: fix spelling mistake "hierarichal" -> "hierarchical"]
Link: https://lkml.kernel.org/r/20211125090635.23508-1-colin.i.king@gmail.com
[keescook@chromium.org: fix copy/paste array assignment]
Link: https://lkml.kernel.org/r/20211203065647.2819707-1-keescook@chromium.org

Link: https://lkml.kernel.org/r/20211123001020.4083653-1-almasrymina@google.com
Signed-off-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jue Wang <juew@google.com>
Cc: Yang Yao <ygyao@google.com>
Cc: Joanna Li <joannali@google.com>
Cc: Cannon Matthews <cannonmatthews@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hugetlb_cgroup: add hugetlb_cgroup reservation docs

Add docs for how to use hugetlb_cgroup reservations, and their behavior.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Sandipan Das <sandipan@linux.ibm.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Link: http://lkml.kernel.org/r/20200211213128.73302-9-almasrymina@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

docs: cgroup-v1: add it to the admin-guide book

Those files belong to the admin guide, so add them.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>