From: Shakeel Butt <shakeelb@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Jan Kara <jack@suse.com>, Greg Thelen <gthelen@google.com>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
Shakeel Butt <shakeelb@google.com>, Jan Kara <jack@suse.cz>,
Alexander Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH 3/3] fs, mm: account buffer_head to kmemcg
Date: Mon, 18 Jun 2018 22:13:27 -0700 [thread overview]
Message-ID: <20180619051327.149716-4-shakeelb@google.com> (raw)
In-Reply-To: <20180619051327.149716-1-shakeelb@google.com>
The buffer_head can consume a significant amount of system memory and
is directly related to the amount of page cache. In our production
environment we have observed that a lot of machines are spending a
significant amount of memory as buffer_head and can not be left as
system memory overhead.
Charging buffer_head is not as simple as adding __GFP_ACCOUNT to the
allocation. The buffer_heads can be allocated in a memcg different from
the memcg of the page for which buffer_heads are being allocated. One
concrete example is memory reclaim. The reclaim can trigger I/O of pages
of any memcg on the system. So, the right way to charge buffer_head is
to extract the memcg from the page for which buffer_heads are being
allocated and then use targeted memcg charging API.
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
fs/buffer.c | 14 +++++++++++++-
include/linux/memcontrol.h | 7 +++++++
mm/memcontrol.c | 21 +++++++++++++++++++++
3 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 8194e3049fc5..26389b7a3cab 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -815,10 +815,17 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
struct buffer_head *bh, *head;
gfp_t gfp = GFP_NOFS;
long offset;
+ struct mem_cgroup *old_memcg;
+ struct mem_cgroup *memcg = get_mem_cgroup_from_page(page);
if (retry)
gfp |= __GFP_NOFAIL;
+ if (memcg) {
+ gfp |= __GFP_ACCOUNT;
+ old_memcg = memalloc_memcg_save(memcg);
+ }
+
head = NULL;
offset = PAGE_SIZE;
while ((offset -= size) >= 0) {
@@ -835,6 +842,11 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
/* Link the buffer to its page */
set_bh_page(bh, page, offset);
}
+out:
+ if (memcg) {
+ memalloc_memcg_restore(old_memcg);
+#ifdef CONFIG_MEMCG
+ css_put(&memcg->css);
+#endif
+ }
return head;
/*
* In case anything failed, we just free everything we got.
@@ -848,7 +860,7 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
} while (head);
}
- return NULL;
+ goto out;
}
EXPORT_SYMBOL_GPL(alloc_page_buffers);
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 6c857be8a9b7..d53609978eb7 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -380,6 +380,8 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
+struct mem_cgroup *get_mem_cgroup_from_page(struct page *page);
+
static inline
struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
return css ? container_of(css, struct mem_cgroup, css) : NULL;
@@ -864,6 +866,11 @@ static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
return NULL;
}
+static inline struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
+{
+ return NULL;
+}
+
static inline void mem_cgroup_put(struct mem_cgroup *memcg)
{
}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c481e661e051..f9a9a79117b9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -712,6 +712,27 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
return memcg;
}
+/**
+ * get_mem_cgroup_from_page: Obtain a reference on given page's memcg.
+ * @page: page from which memcg should be extracted.
+ *
+ * Obtain a reference on page->memcg and returns it if successful. Otherwise
+ * NULL is returned.
+ */
+struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
+{
+ struct mem_cgroup *memcg = page->mem_cgroup;
+
+ if (mem_cgroup_disabled() || !memcg)
+ return NULL;
+
+ rcu_read_lock();
+ if (!css_tryget_online(&memcg->css))
+ memcg = NULL;
+ rcu_read_unlock();
+ return memcg;
+}
+
static __always_inline struct mem_cgroup *get_mem_cgroup(
struct mem_cgroup *memcg, struct mm_struct *mm)
{
--
2.18.0.rc1.244.gcf134e6275-goog
next prev parent reply other threads:[~2018-06-19 5:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-19 5:13 [PATCH v6 0/3] Directed kmem charging Shakeel Butt
2018-06-19 5:13 ` [PATCH 1/3] mm: memcg: remote memcg charging for kmem allocations Shakeel Butt
2018-06-19 16:24 ` Johannes Weiner
2018-06-19 23:31 ` Shakeel Butt
2018-06-20 15:22 ` Johannes Weiner
2018-06-19 5:13 ` [PATCH 2/3] fs: fsnotify: account fsnotify metadata to kmemcg Shakeel Butt
2018-06-19 7:20 ` Amir Goldstein
2018-06-19 14:15 ` Shakeel Butt
2018-06-19 5:13 ` Shakeel Butt [this message]
2018-06-19 16:27 ` [PATCH 3/3] fs, mm: account buffer_head " Johannes Weiner
2018-06-19 17:40 ` Roman Gushchin
2018-06-19 19:51 ` Shakeel Butt
2018-06-19 19:55 ` Roman Gushchin
2018-06-22 23:33 ` Shakeel Butt
2018-06-19 16:11 ` [PATCH v6 0/3] Directed kmem charging Johannes Weiner
2018-06-19 22:58 ` Shakeel Butt
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