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Message-Id: <20190826233240.11524-4-almasrymina@google.com>
Date: Mon, 26 Aug 2019 16:32:37 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: mike.kravetz@...cle.com
Cc: shuah@...nel.org, almasrymina@...gle.com, rientjes@...gle.com,
shakeelb@...gle.com, gthelen@...gle.com, akpm@...ux-foundation.org,
khalid.aziz@...cle.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
cgroups@...r.kernel.org, aneesh.kumar@...ux.vnet.ibm.com,
mkoutny@...e.com
Subject: [PATCH v3 3/6] hugetlb_cgroup: add reservation accounting for private mappings
Normally the pointer to the cgroup to uncharge hangs off the struct
page, and gets queried when it's time to free the page. With
hugetlb_cgroup reservations, this is not possible. Because it's possible
for a page to be reserved by one task and actually faulted in by another
task.
The best place to put the hugetlb_cgroup pointer to uncharge for
reservations is in the resv_map. But, because the resv_map has different
semantics for private and shared mappings, the code patch to
charge/uncharge shared and private mappings is different. This patch
implements charging and uncharging for private mappings.
For private mappings, the counter to uncharge is in
resv_map->reservation_counter. On initializing the resv_map this is set
to NULL. On reservation of a region in private mapping, the tasks
hugetlb_cgroup is charged and the hugetlb_cgroup is placed is
resv_map->reservation_counter.
On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter.
---
include/linux/hugetlb.h | 8 ++++++
include/linux/hugetlb_cgroup.h | 11 ++++++++
mm/hugetlb.c | 47 ++++++++++++++++++++++++++++++++--
mm/hugetlb_cgroup.c | 12 ---------
4 files changed, 64 insertions(+), 14 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 128ff1aff1c93..536cb144cf484 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -46,6 +46,14 @@ struct resv_map {
long adds_in_progress;
struct list_head region_cache;
long region_cache_count;
+ #ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * On private mappings, the counter to uncharge reservations is stored
+ * here. If these fields are 0, then the mapping is shared.
+ */
+ struct page_counter *reservation_counter;
+ unsigned long pages_per_hpage;
+#endif
};
extern struct resv_map *resv_map_alloc(void);
void resv_map_release(struct kref *ref);
diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index 0725f809cd2d9..1fdde63a4e775 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -25,6 +25,17 @@ struct hugetlb_cgroup;
#define HUGETLB_CGROUP_MIN_ORDER 2
#ifdef CONFIG_CGROUP_HUGETLB
+struct hugetlb_cgroup {
+ struct cgroup_subsys_state css;
+ /*
+ * the counter to account for hugepages from hugetlb.
+ */
+ struct page_counter hugepage[HUGE_MAX_HSTATE];
+ /*
+ * the counter to account for hugepage reservations from hugetlb.
+ */
+ struct page_counter reserved_hugepage[HUGE_MAX_HSTATE];
+};
static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
{
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 242cfeb7cc3e1..7c2df7574cf50 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -711,6 +711,16 @@ struct resv_map *resv_map_alloc(void)
INIT_LIST_HEAD(&resv_map->regions);
resv_map->adds_in_progress = 0;
+#ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * Initialize these to 0. On shared mappings, 0's here indicate these
+ * fields don't do cgroup accounting. On private mappings, these will be
+ * re-initialized to the proper values, to indicate that hugetlb cgroup
+ * reservations are to be un-charged from here.
+ */
+ resv_map->reservation_counter = NULL;
+ resv_map->pages_per_hpage = 0;
+#endif
INIT_LIST_HEAD(&resv_map->region_cache);
list_add(&rg->link, &resv_map->region_cache);
@@ -3192,7 +3202,19 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
reserve = (end - start) - region_count(resv, start, end);
- kref_put(&resv->refs, resv_map_release);
+#ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * Since we check for HPAGE_RESV_OWNER above, this must a private
+ * mapping, and these values should be none-zero, and should point to
+ * the hugetlb_cgroup counter to uncharge for this reservation.
+ */
+ WARN_ON(!resv->reservation_counter);
+ WARN_ON(!resv->pages_per_hpage);
+
+ hugetlb_cgroup_uncharge_counter(
+ resv->reservation_counter,
+ (end - start) * resv->pages_per_hpage);
+#endif
if (reserve) {
/*
@@ -3202,6 +3224,8 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
gbl_reserve = hugepage_subpool_put_pages(spool, reserve);
hugetlb_acct_memory(h, -gbl_reserve);
}
+
+ kref_put(&resv->refs, resv_map_release);
}
static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr)
@@ -4535,6 +4559,7 @@ int hugetlb_reserve_pages(struct inode *inode,
struct hstate *h = hstate_inode(inode);
struct hugepage_subpool *spool = subpool_inode(inode);
struct resv_map *resv_map;
+ struct hugetlb_cgroup *h_cg;
long gbl_reserve;
/* This should never happen */
@@ -4568,11 +4593,29 @@ int hugetlb_reserve_pages(struct inode *inode,
chg = region_chg(resv_map, from, to);
} else {
+ /* Private mapping. */
+ chg = to - from;
+
+ if (hugetlb_cgroup_charge_cgroup(
+ hstate_index(h),
+ chg * pages_per_huge_page(h),
+ &h_cg, true)) {
+ return -ENOMEM;
+ }
+
resv_map = resv_map_alloc();
if (!resv_map)
return -ENOMEM;
- chg = to - from;
+#ifdef CONFIG_CGROUP_HUGETLB
+ /*
+ * Since this branch handles private mappings, we attach the
+ * counter to uncharge for this reservation off resv_map.
+ */
+ resv_map->reservation_counter =
+ &h_cg->reserved_hugepage[hstate_index(h)];
+ resv_map->pages_per_hpage = pages_per_huge_page(h);
+#endif
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index bd9b58474be51..1db97439bdb57 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -19,18 +19,6 @@
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
-struct hugetlb_cgroup {
- struct cgroup_subsys_state css;
- /*
- * the counter to account for hugepages from hugetlb.
- */
- struct page_counter hugepage[HUGE_MAX_HSTATE];
- /*
- * the counter to account for hugepage reservations from hugetlb.
- */
- struct page_counter reserved_hugepage[HUGE_MAX_HSTATE];
-};
-
#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
#define MEMFILE_IDX(val) (((val) >> 16) & 0xffff)
#define MEMFILE_ATTR(val) ((val) & 0xffff)
--
2.23.0.187.g17f5b7556c-goog
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