[PATCH v11 2/9] hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations

From: Mina Almasry
Date: Mon Feb 03 2020 - 18:23:07 EST

Augments hugetlb_cgroup_charge_cgroup to be able to charge hugetlb
usage or hugetlb reservation counter.

Adds a new interface to uncharge a hugetlb_cgroup counter via
hugetlb_cgroup_uncharge_counter.

Integrates the counter with hugetlb_cgroup, via hugetlb_cgroup_init,
hugetlb_cgroup_have_usage, and hugetlb_cgroup_css_offline.

Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
Acked-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>

---

Changes in v11:
- Changed all 'reserved' or 'reservation' to 'rsvd' to reflect the user
interface.
- Expanded comment that describes tail pages usage.
facing naming.
Changes in v10:
- Added missing VM_BUG_ON
Changes in V9:
- Fixed HUGETLB_CGROUP_MIN_ORDER.
- Minor variable name update.
- Moved some init/cleanup code from later patches in the series to this patch.
- Updated reparenting of reservation accounting.

---
include/linux/hugetlb_cgroup.h | 66 +++++++++++++--------
mm/hugetlb.c | 19 +++---
mm/hugetlb_cgroup.c | 103 ++++++++++++++++++++++++---------
3 files changed, 128 insertions(+), 60 deletions(-)

diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index 063962f6dfc6a..91bc5e920e9d0 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -20,29 +20,38 @@
struct hugetlb_cgroup;
/*
* Minimum page order trackable by hugetlb cgroup.
- * At least 3 pages are necessary for all the tracking information.
+ * At least 4 pages are necessary for all the tracking information.
+ * The second tail page (hpage[2]) is the fault usage cgroup.
+ * The third tail page (hpage[3]) is the reservation usage cgroup.
*/
#define HUGETLB_CGROUP_MIN_ORDER 2

#ifdef CONFIG_CGROUP_HUGETLB

-static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
+static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page,
+ bool rsvd)
{
VM_BUG_ON_PAGE(!PageHuge(page), page);

if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
return NULL;
- return (struct hugetlb_cgroup *)page[2].private;
+ if (rsvd)
+ return (struct hugetlb_cgroup *)page[3].private;
+ else
+ return (struct hugetlb_cgroup *)page[2].private;
}

-static inline
-int set_hugetlb_cgroup(struct page *page, struct hugetlb_cgroup *h_cg)
+static inline int set_hugetlb_cgroup(struct page *page,
+ struct hugetlb_cgroup *h_cg, bool rsvd)
{
VM_BUG_ON_PAGE(!PageHuge(page), page);

if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
return -1;
- page[2].private = (unsigned long)h_cg;
+ if (rsvd)
+ page[3].private = (unsigned long)h_cg;
+ else
+ page[2].private = (unsigned long)h_cg;
return 0;
}

@@ -52,26 +61,33 @@ static inline bool hugetlb_cgroup_disabled(void)
}

extern int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup **ptr);
+ struct hugetlb_cgroup **ptr, bool rsvd);
extern void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
struct hugetlb_cgroup *h_cg,
- struct page *page);
+ struct page *page, bool rsvd);
extern void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
- struct page *page);
+ struct page *page, bool rsvd);
+
extern void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup *h_cg);
+ struct hugetlb_cgroup *h_cg,
+ bool rsvd);
+extern void hugetlb_cgroup_uncharge_counter(struct page_counter *p,
+ unsigned long nr_pages,
+ struct cgroup_subsys_state *css);
+
extern void hugetlb_cgroup_file_init(void) __init;
extern void hugetlb_cgroup_migrate(struct page *oldhpage,
struct page *newhpage);

#else
-static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
+static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page,
+ bool rsvd)
{
return NULL;
}

-static inline
-int set_hugetlb_cgroup(struct page *page, struct hugetlb_cgroup *h_cg)
+static inline int set_hugetlb_cgroup(struct page *page,
+ struct hugetlb_cgroup *h_cg, bool rsvd)
{
return 0;
}
@@ -81,28 +97,28 @@ static inline bool hugetlb_cgroup_disabled(void)
return true;
}

-static inline int
-hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup **ptr)
+static inline int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
+ struct hugetlb_cgroup **ptr,
+ bool rsvd)
{
return 0;
}

-static inline void
-hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup *h_cg,
- struct page *page)
+static inline void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
+ struct hugetlb_cgroup *h_cg,
+ struct page *page, bool rsvd)
{
}

-static inline void
-hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages, struct page *page)
+static inline void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
+ struct page *page, bool rsvd)
{
}

-static inline void
-hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup *h_cg)
+static inline void hugetlb_cgroup_uncharge_cgroup(int idx,
+ unsigned long nr_pages,
+ struct hugetlb_cgroup *h_cg,
+ bool rsvd)
{
}

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index dd8737a94bec4..62a4cf3db4090 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1068,7 +1068,8 @@ static void update_and_free_page(struct hstate *h, struct page *page)
1 << PG_active | 1 << PG_private |
1 << PG_writeback);
}
- VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
+ VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page, false), page);
+ VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page, true), page);
set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
set_page_refcounted(page);
if (hstate_is_gigantic(h)) {
@@ -1178,8 +1179,8 @@ static void __free_huge_page(struct page *page)

spin_lock(&hugetlb_lock);
clear_page_huge_active(page);
- hugetlb_cgroup_uncharge_page(hstate_index(h),
- pages_per_huge_page(h), page);
+ hugetlb_cgroup_uncharge_page(hstate_index(h), pages_per_huge_page(h),
+ page, false);
if (restore_reserve)
h->resv_huge_pages++;

@@ -1253,7 +1254,8 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
INIT_LIST_HEAD(&page->lru);
set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
spin_lock(&hugetlb_lock);
- set_hugetlb_cgroup(page, NULL);
+ set_hugetlb_cgroup(page, NULL, false);
+ set_hugetlb_cgroup(page, NULL, true);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
spin_unlock(&hugetlb_lock);
@@ -2039,7 +2041,8 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
gbl_chg = 1;
}

- ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
+ ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg,
+ false);
if (ret)
goto out_subpool_put;

@@ -2063,7 +2066,8 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
list_move(&page->lru, &h->hugepage_activelist);
/* Fall through */
}
- hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
+ hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page,
+ false);
spin_unlock(&hugetlb_lock);

set_page_private(page, (unsigned long)spool);
@@ -2087,7 +2091,8 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
return page;

out_uncharge_cgroup:
- hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
+ hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg,
+ false);
out_subpool_put:
if (map_chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index cd1f44775259c..640555d7f78c6 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -97,8 +97,12 @@ static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
int idx;

for (idx = 0; idx < hugetlb_max_hstate; idx++) {
- if (page_counter_read(&h_cg->hugepage[idx]))
+ if (page_counter_read(hugetlb_cgroup_counter_from_cgroup(
+ h_cg, idx, true)) ||
+ page_counter_read(hugetlb_cgroup_counter_from_cgroup(
+ h_cg, idx, false))) {
return true;
+ }
}
return false;
}
@@ -109,18 +113,34 @@ static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,
int idx;

for (idx = 0; idx < HUGE_MAX_HSTATE; idx++) {
- struct page_counter *counter = &h_cgroup->hugepage[idx];
- struct page_counter *parent = NULL;
+ struct page_counter *fault_parent = NULL;
+ struct page_counter *rsvd_parent = NULL;
unsigned long limit;
int ret;

- if (parent_h_cgroup)
- parent = &parent_h_cgroup->hugepage[idx];
- page_counter_init(counter, parent);
+ if (parent_h_cgroup) {
+ fault_parent = hugetlb_cgroup_counter_from_cgroup(
+ parent_h_cgroup, idx, false);
+ rsvd_parent = hugetlb_cgroup_counter_from_cgroup(
+ parent_h_cgroup, idx, true);
+ }
+ page_counter_init(hugetlb_cgroup_counter_from_cgroup(
+ h_cgroup, idx, false),
+ fault_parent);
+ page_counter_init(hugetlb_cgroup_counter_from_cgroup(h_cgroup,
+ idx, true),
+ rsvd_parent);

limit = round_down(PAGE_COUNTER_MAX,
1 << huge_page_order(&hstates[idx]));
- ret = page_counter_set_max(counter, limit);
+
+ ret = page_counter_set_max(hugetlb_cgroup_counter_from_cgroup(
+ h_cgroup, idx, false),
+ limit);
+ VM_BUG_ON(ret);
+ ret = page_counter_set_max(
+ hugetlb_cgroup_counter_from_cgroup(h_cgroup, idx, true),
+ limit);
VM_BUG_ON(ret);
}
}
@@ -150,7 +170,6 @@ static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
kfree(h_cgroup);
}

-
/*
* Should be called with hugetlb_lock held.
* Since we are holding hugetlb_lock, pages cannot get moved from
@@ -166,7 +185,7 @@ static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
struct hugetlb_cgroup *page_hcg;
struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);

- page_hcg = hugetlb_cgroup_from_page(page);
+ page_hcg = hugetlb_cgroup_from_page(page, false);
/*
* We can have pages in active list without any cgroup
* ie, hugepage with less than 3 pages. We can safely
@@ -185,7 +204,7 @@ static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
/* Take the pages off the local counter */
page_counter_cancel(counter, nr_pages);

- set_hugetlb_cgroup(page, parent);
+ set_hugetlb_cgroup(page, parent, false);
out:
return;
}
@@ -228,7 +247,7 @@ static inline void hugetlb_event(struct hugetlb_cgroup *hugetlb, int idx,
}

int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup **ptr)
+ struct hugetlb_cgroup **ptr, bool rsvd)
{
int ret = 0;
struct page_counter *counter;
@@ -251,13 +270,20 @@ int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
}
rcu_read_unlock();

- if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages,
- &counter)) {
+ if (!page_counter_try_charge(
+ hugetlb_cgroup_counter_from_cgroup(h_cg, idx, rsvd),
+ nr_pages, &counter)) {
ret = -ENOMEM;
hugetlb_event(hugetlb_cgroup_from_counter(counter, idx), idx,
HUGETLB_MAX);
+ css_put(&h_cg->css);
+ goto done;
}
- css_put(&h_cg->css);
+ /* Reservations take a reference to the css because they do not get
+ * reparented.
+ */
+ if (!rsvd)
+ css_put(&h_cg->css);
done:
*ptr = h_cg;
return ret;
@@ -266,12 +292,12 @@ int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
/* Should be called with hugetlb_lock held */
void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
struct hugetlb_cgroup *h_cg,
- struct page *page)
+ struct page *page, bool rsvd)
{
if (hugetlb_cgroup_disabled() || !h_cg)
return;

- set_hugetlb_cgroup(page, h_cg);
+ set_hugetlb_cgroup(page, h_cg, rsvd);
return;
}

@@ -279,23 +305,29 @@ void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
* Should be called with hugetlb_lock held
*/
void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
- struct page *page)
+ struct page *page, bool rsvd)
{
struct hugetlb_cgroup *h_cg;

if (hugetlb_cgroup_disabled())
return;
lockdep_assert_held(&hugetlb_lock);
- h_cg = hugetlb_cgroup_from_page(page);
+ h_cg = hugetlb_cgroup_from_page(page, rsvd);
if (unlikely(!h_cg))
return;
- set_hugetlb_cgroup(page, NULL);
- page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
+ set_hugetlb_cgroup(page, NULL, rsvd);
+
+ page_counter_uncharge(
+ hugetlb_cgroup_counter_from_cgroup(h_cg, idx, rsvd), nr_pages);
+
+ if (rsvd)
+ css_put(&h_cg->css);
+
return;
}

void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
- struct hugetlb_cgroup *h_cg)
+ struct hugetlb_cgroup *h_cg, bool rsvd)
{
if (hugetlb_cgroup_disabled() || !h_cg)
return;
@@ -303,8 +335,22 @@ void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
return;

- page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
- return;
+ page_counter_uncharge(
+ hugetlb_cgroup_counter_from_cgroup(h_cg, idx, rsvd), nr_pages);
+
+ if (rsvd)
+ css_put(&h_cg->css);
+}
+
+void hugetlb_cgroup_uncharge_counter(struct page_counter *p,
+ unsigned long nr_pages,
+ struct cgroup_subsys_state *css)
+{
+ if (hugetlb_cgroup_disabled() || !p || !css)
+ return;
+
+ page_counter_uncharge(p, nr_pages);
+ css_put(css);
}

enum {
@@ -450,8 +496,7 @@ static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));

counter = &h_cg->hugepage[MEMFILE_IDX(of_cft(of)->private)];
- rsvd_counter =
- &h_cg->rsvd_hugepage[MEMFILE_IDX(of_cft(of)->private)];
+ rsvd_counter = &h_cg->rsvd_hugepage[MEMFILE_IDX(of_cft(of)->private)];

switch (MEMFILE_ATTR(of_cft(of)->private)) {
case RES_MAX_USAGE:
@@ -676,6 +721,7 @@ void __init hugetlb_cgroup_file_init(void)
void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
{
struct hugetlb_cgroup *h_cg;
+ struct hugetlb_cgroup *h_cg_rsvd;
struct hstate *h = page_hstate(oldhpage);

if (hugetlb_cgroup_disabled())
@@ -683,11 +729,12 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)

VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
spin_lock(&hugetlb_lock);
- h_cg = hugetlb_cgroup_from_page(oldhpage);
- set_hugetlb_cgroup(oldhpage, NULL);
+ h_cg = hugetlb_cgroup_from_page(oldhpage, false);
+ h_cg_rsvd = hugetlb_cgroup_from_page(oldhpage, true);
+ set_hugetlb_cgroup(oldhpage, NULL, false);

/* move the h_cg details to new cgroup */
- set_hugetlb_cgroup(newhpage, h_cg);
+ set_hugetlb_cgroup(newhpage, h_cg_rsvd, true);
list_move(&newhpage->lru, &h->hugepage_activelist);
spin_unlock(&hugetlb_lock);
return;
--
2.25.0.341.g760bfbb309-goog