[Devel,RHEL7,COMMIT] ms/memcg: get_mem_cgroup_from_mm()

Submitted by Konstantin Khorenko on Jan. 16, 2017, 4:27 p.m.

Details

Message ID 201701161627.v0GGR5QF027672@finist_cl7.x64_64.work.ct
State New
Series "Series without cover letter"
Headers show

Commit Message

Konstantin Khorenko Jan. 16, 2017, 4:27 p.m.
The commit is pushed to "branch-rh7-3.10.0-514.vz7.27.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.vz7.27.10
------>
commit a7ec2fa951e33ca41ceee0fae9bf4926a431ff40
Author: Johannes Weiner <hannes@cmpxchg.org>
Date:   Mon Jan 16 20:27:05 2017 +0400

    ms/memcg: get_mem_cgroup_from_mm()
    
    Instead of returning NULL from try_get_mem_cgroup_from_mm() when the mm
    owner is exiting, just return root_mem_cgroup.  This makes sense for all
    callsites and gets rid of some of them having to fallback manually.
    
    [fengguang.wu@intel.com: fix warnings]
    Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
    Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
    Acked-by: Michal Hocko <mhocko@suse.cz>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-51558
    (cherry picked from commit df381975463996178d685f6ef7d3555c5f887201)
    Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 include/linux/memcontrol.h | 12 ++++++------
 mm/memcontrol.c            | 37 +++++++++++++++++--------------------
 mm/oom_kill.c              |  4 ++--
 net/packet/af_packet.c     |  2 +-
 4 files changed, 26 insertions(+), 29 deletions(-)

Patch hide | download patch | download mbox

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index f1b599f..bcf7752 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -85,7 +85,7 @@  int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
 
 extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
 extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
-extern struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm);
+extern struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
 
 extern struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
 extern struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont);
@@ -304,17 +304,17 @@  static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
 	return NULL;
 }
 
-static inline struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
-{
-	return NULL;
-}
-
 static inline bool mm_match_cgroup(struct mm_struct *mm,
 		struct mem_cgroup *memcg)
 {
 	return true;
 }
 
+static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
+{
+       return NULL;
+}
+
 static inline int task_in_mem_cgroup(struct task_struct *task,
 				     const struct mem_cgroup *memcg)
 {
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d09d55d9..40ac81b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1166,15 +1166,24 @@  struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 	return mem_cgroup_from_css(task_subsys_state(p, mem_cgroup_subsys_id));
 }
 
-struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
+struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
 {
 	struct mem_cgroup *memcg = NULL;
 
 	rcu_read_lock();
 	do {
-		memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
-		if (unlikely(!memcg))
-			break;
+		/*
+		 * Page cache insertions can happen withou an
+		 * actual mm context, e.g. during disk probing
+		 * on boot, loopback IO, acct() writes etc.
+		 */
+		if (unlikely(!mm))
+			memcg = root_mem_cgroup;
+		else {
+			memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+			if (unlikely(!memcg))
+				memcg = root_mem_cgroup;
+		}
 	} while (!css_tryget(&memcg->css));
 	rcu_read_unlock();
 	return memcg;
@@ -1546,7 +1555,7 @@  int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
 
 	p = find_lock_task_mm(task);
 	if (p) {
-		curr = try_get_mem_cgroup_from_mm(p->mm);
+		curr = get_mem_cgroup_from_mm(p->mm);
 		task_unlock(p);
 	} else {
 		/*
@@ -1560,8 +1569,6 @@  int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
 			css_get(&curr->css);
 		task_unlock(task);
 	}
-	if (!curr)
-		return 0;
 	/*
 	 * We should check use_hierarchy of "memcg" not "curr". Because checking
 	 * use_hierarchy of "curr" here make this function true if hierarchy is
@@ -1693,7 +1700,7 @@  void mem_cgroup_note_oom_kill(struct mem_cgroup *root_memcg,
 
 	p = find_lock_task_mm(task);
 	if (p) {
-		memcg = try_get_mem_cgroup_from_mm(p->mm);
+		memcg = get_mem_cgroup_from_mm(p->mm);
 		task_unlock(p);
 	} else {
 		rcu_read_lock();
@@ -3458,9 +3465,7 @@  struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
 	if (!current->mm || current->memcg_kmem_skip_account)
 		return cachep;
 
-	memcg = try_get_mem_cgroup_from_mm(current->mm);
-	if (unlikely(!memcg))
-		return cachep;
+	memcg = get_mem_cgroup_from_mm(current->mm);
 
 	if (!memcg_kmem_is_active(memcg))
 		goto out;
@@ -3543,15 +3548,7 @@  __memcg_kmem_newpage_charge(struct page *page, gfp_t gfp, int order)
 	if (!current->mm || current->memcg_kmem_skip_account)
 		return true;
 
-	memcg = try_get_mem_cgroup_from_mm(current->mm);
-
-	/*
-	 * very rare case described in mem_cgroup_from_task. Unfortunately there
-	 * isn't much we can do without complicating this too much, and it would
-	 * be gfp-dependent anyway. Just let it go
-	 */
-	if (unlikely(!memcg))
-		return true;
+	memcg = get_mem_cgroup_from_mm(current->mm);
 
 	if (!memcg_kmem_is_active(memcg)) {
 		css_put(&memcg->css);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6b0542c2..a82433f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -182,7 +182,7 @@  static unsigned long mm_overdraft(struct mm_struct *mm)
 	struct oom_context *ctx;
 	unsigned long overdraft;
 
-	memcg = try_get_mem_cgroup_from_mm(mm);
+	memcg = get_mem_cgroup_from_mm(mm);
 	ctx = mem_cgroup_oom_context(memcg);
 	overdraft = ctx->overdraft;
 	if (memcg)
@@ -476,7 +476,7 @@  void mark_oom_victim(struct task_struct *tsk)
 	 * owner memcg so that others can wait for it to exit. It will
 	 * be cleared in exit_oom_victim.
 	 */
-	memcg = try_get_mem_cgroup_from_mm(tsk->mm);
+	memcg = get_mem_cgroup_from_mm(tsk->mm);
 	ctx = mem_cgroup_oom_context(memcg);
 	spin_lock(&oom_context_lock);
 	if (!ctx->victim) {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index f58fa90..c15e57a 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2521,7 +2521,7 @@  static struct cg_proto *packet_sk_charge(void)
 		goto out;
 
 	err = 0;
-	psc->memcg = try_get_mem_cgroup_from_mm(current->mm);
+	psc->memcg = get_mem_cgroup_from_mm(current->mm);
 	if (!psc->memcg)
 		goto out_free_psc;
 	if (!memcg_kmem_is_active(psc->memcg))