In the effort of supporting cgroups v2 into Kubernetes, I stumped on
the lack of the hugetlb controller.
When the controller is enabled, it exposes three new files for each
hugetlb size on non-root cgroups:
- hugetlb.<hugepagesize>.current
- hugetlb.<hugepagesize>.max
- hugetlb.<hugepagesize>.stat
The differences with the legacy hierarchy are in the file names and
using the value "max" instead of "-1" to disable a limit.
The file .limit_in_bytes is renamed to .max.
The file .usage_in_bytes is renamed to .usage.
.failcnt and .max_usage_in_bytes are not provided as single files
anymore, but their value can be read through the new flat-keyed file
.stat, respectively through the max_usage and failcnt keys.
Signed-off-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 28 +++++
include/linux/hugetlb.h | 3 +-
mm/hugetlb_cgroup.c | 142 ++++++++++++++++++++++--
3 files changed, 162 insertions(+), 11 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 5361ebec3361..662cb39abbf5 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -61,6 +61,8 @@ v1 is available under Documentation/admin-guide/cgroup-v1/.
5-6. Device
5-7. RDMA
5-7-1. RDMA Interface Files
+ 5-8. HugeTLB
+ 5.8-1. HugeTLB Interface Files
5-8. Misc
5-8-1. perf_event
5-N. Non-normative information
@@ -2050,6 +2052,32 @@ RDMA Interface Files
mlx4_0 hca_handle=1 hca_object=20
ocrdma1 hca_handle=1 hca_object=23
+HugeTLB
+-------
+
+The HugeTLB controller allows to limit the HugeTLB usage per control group and
+enforces the controller limit during page fault.
+
+HugeTLB Interface Files
+~~~~~~~~~~~~~~~~~~~~~~~
+
+ hugetlb.<hugepagesize>.current
+ Show current usage for "hugepagesize" hugetlb. The default
+ value is "max". It exists for all the cgroup except root.
+
+
+ hugetlb.<hugepagesize>.max
+ Set/show the hard limit of "hugepagesize" hugetlb usage.
+ The default value is "max". It exists for all the cgroup except root.
+
+ hugetlb.<hugepagesize>.stat
+ A read-only flat-keyed file which exists on non-root cgroups.
+
+ max_usage
+ Maximum HugeTLB usage recorded
+
+ failcnt
+ The number of allocation failure due to HugeTLB limit
Misc
----
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 53fc34f930d0..1c2bacbca044 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -340,7 +340,8 @@ struct hstate {
unsigned int surplus_huge_pages_node[MAX_NUMNODES];
#ifdef CONFIG_CGROUP_HUGETLB
/* cgroup control files */
- struct cftype cgroup_files[5];
+ struct cftype cgroup_files_dfl[5];
+ struct cftype cgroup_files_legacy[5];
#endif
char name[HSTATE_NAME_LEN];
};
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 2ac38bdc18a1..d4dbf5203324 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -283,10 +283,55 @@ static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
}
}
+static int hugetlb_cgroup_read_u64_max(struct seq_file *seq, void *v)
+{
+ int idx;
+ u64 val;
+ bool write_raw = false;
+ struct cftype *cft = seq_cft(seq);
+ unsigned long limit;
+ struct page_counter *counter;
+ struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(seq_css(seq));
+
+ idx = MEMFILE_IDX(cft->private);
+ counter = &h_cg->hugepage[idx];
+
+ switch (MEMFILE_ATTR(cft->private)) {
+ case RES_USAGE:
+ val = (u64)page_counter_read(counter);
+ break;
+ case RES_LIMIT:
+ val = (u64)counter->max;
+ break;
+ case RES_MAX_USAGE:
+ val = (u64)counter->watermark;
+ break;
+ case RES_FAILCNT:
+ val = counter->failcnt;
+ write_raw = true;
+ break;
+ default:
+ BUG();
+ }
+
+ limit = round_down(PAGE_COUNTER_MAX,
+ 1 << huge_page_order(&hstates[idx]));
+
+ if (val == limit && !write_raw)
+ seq_puts(seq, "max\n");
+ else if (write_raw)
+ seq_printf(seq, "%llu\n", val);
+ else
+ seq_printf(seq, "%llu\n", val * PAGE_SIZE);
+
+ return 0;
+}
+
static DEFINE_MUTEX(hugetlb_limit_mutex);
static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
+ char *buf, size_t nbytes, loff_t off,
+ const char *max)
{
int ret, idx;
unsigned long nr_pages;
@@ -296,7 +341,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
return -EINVAL;
buf = strstrip(buf);
- ret = page_counter_memparse(buf, "-1", &nr_pages);
+ ret = page_counter_memparse(buf, max, &nr_pages);
if (ret)
return ret;
@@ -316,6 +361,18 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
return ret ?: nbytes;
}
+static ssize_t hugetlb_cgroup_write_legacy(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return hugetlb_cgroup_write(of, buf, nbytes, off, "-1");
+}
+
+static ssize_t hugetlb_cgroup_write_dfl(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return hugetlb_cgroup_write(of, buf, nbytes, off, "max");
+}
+
static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
@@ -350,7 +407,60 @@ static char *mem_fmt(char *buf, int size, unsigned long hsize)
return buf;
}
-static void __init __hugetlb_cgroup_file_init(int idx)
+static int hugetlb_stat_show(struct seq_file *seq, void *v)
+{
+ struct page_counter *counter;
+ struct cftype *cft = seq_cft(seq);
+ struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(seq_css(seq));
+
+ counter = &h_cg->hugepage[MEMFILE_IDX(cft->private)];
+
+ seq_printf(seq, "max_usage %llu\n",
+ (u64)counter->watermark * PAGE_SIZE);
+ seq_printf(seq, "fail_cnt %lu\n", counter->failcnt);
+
+ return 0;
+}
+
+static void __init __hugetlb_cgroup_file_dfl_init(int idx)
+{
+ char buf[32];
+ struct cftype *cft;
+ struct hstate *h = &hstates[idx];
+
+ /* format the size */
+ mem_fmt(buf, 32, huge_page_size(h));
+
+ /* Add the limit file */
+ cft = &h->cgroup_files_dfl[0];
+ snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max", buf);
+ cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
+ cft->seq_show = hugetlb_cgroup_read_u64_max;
+ cft->write = hugetlb_cgroup_write_dfl;
+ cft->flags = CFTYPE_NOT_ON_ROOT;
+
+ /* Add the current usage file */
+ cft = &h->cgroup_files_dfl[1];
+ snprintf(cft->name, MAX_CFTYPE_NAME, "%s.current", buf);
+ cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
+ cft->seq_show = hugetlb_cgroup_read_u64_max;
+ cft->flags = CFTYPE_NOT_ON_ROOT;
+
+ /* Add the stat file */
+ cft = &h->cgroup_files_dfl[2];
+ snprintf(cft->name, MAX_CFTYPE_NAME, "%s.stat", buf);
+ cft->seq_show = hugetlb_stat_show;
+ cft->flags = CFTYPE_NOT_ON_ROOT;
+
+ /* NULL terminate the last cft */
+ cft = &h->cgroup_files_dfl[3];
+ memset(cft, 0, sizeof(*cft));
+
+ WARN_ON(cgroup_add_dfl_cftypes(&hugetlb_cgrp_subsys,
+ h->cgroup_files_dfl));
+}
+
+static void __init __hugetlb_cgroup_file_legacy_init(int idx)
{
char buf[32];
struct cftype *cft;
@@ -360,38 +470,44 @@ static void __init __hugetlb_cgroup_file_init(int idx)
mem_fmt(buf, 32, huge_page_size(h));
/* Add the limit file */
- cft = &h->cgroup_files[0];
+ cft = &h->cgroup_files_legacy[0];
snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
cft->read_u64 = hugetlb_cgroup_read_u64;
- cft->write = hugetlb_cgroup_write;
+ cft->write = hugetlb_cgroup_write_legacy;
/* Add the usage file */
- cft = &h->cgroup_files[1];
+ cft = &h->cgroup_files_legacy[1];
snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
cft->read_u64 = hugetlb_cgroup_read_u64;
/* Add the MAX usage file */
- cft = &h->cgroup_files[2];
+ cft = &h->cgroup_files_legacy[2];
snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
cft->write = hugetlb_cgroup_reset;
cft->read_u64 = hugetlb_cgroup_read_u64;
/* Add the failcntfile */
- cft = &h->cgroup_files[3];
+ cft = &h->cgroup_files_legacy[3];
snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
cft->private = MEMFILE_PRIVATE(idx, RES_FAILCNT);
cft->write = hugetlb_cgroup_reset;
cft->read_u64 = hugetlb_cgroup_read_u64;
/* NULL terminate the last cft */
- cft = &h->cgroup_files[4];
+ cft = &h->cgroup_files_legacy[4];
memset(cft, 0, sizeof(*cft));
WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
- h->cgroup_files));
+ h->cgroup_files_legacy));
+}
+
+static void __init __hugetlb_cgroup_file_init(int idx)
+{
+ __hugetlb_cgroup_file_dfl_init(idx);
+ __hugetlb_cgroup_file_legacy_init(idx);
}
void __init hugetlb_cgroup_file_init(void)
@@ -433,8 +549,14 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
return;
}
+static struct cftype hugetlb_files[] = {
+ {} /* terminate */
+};
+
struct cgroup_subsys hugetlb_cgrp_subsys = {
.css_alloc = hugetlb_cgroup_css_alloc,
.css_offline = hugetlb_cgroup_css_offline,
.css_free = hugetlb_cgroup_css_free,
+ .dfl_cftypes = hugetlb_files,
+ .legacy_cftypes = hugetlb_files,
};
--
2.23.0
