[patch 0/7] mm: memcg fixlets for 3.3 v2

[patch 0/7] mm: memcg fixlets for 3.3 v2

[Johannes Weiner]

Version 2:
o dropped the non-atomic bitops against pc->flags (Hugh et al)
o added VM_BUG_ONs where page sanity checks were removed (Kame)
o made the page_cgroup array checks in lookup_page_cgroup()
  depend on CONFIG_DEBUG_VM, like the only caller that needs 'em
o added ack tags

 include/linux/memcontrol.h |   16 ++++----
 include/linux/oom.h        |    2 +-
 include/linux/rmap.h       |    4 +-
 mm/memcontrol.c            |   96 ++++++++++++++++++--------------------------
 mm/oom_kill.c              |   42 ++++++++++----------
 mm/page_cgroup.c           |   18 +++++++-
 mm/rmap.c                  |   20 +++++-----
 mm/swapfile.c              |    9 ++--
 mm/vmscan.c                |   12 +++---
 9 files changed, 108 insertions(+), 111 deletions(-)

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[patch 1/7] mm: oom_kill: remove memcg argument from oom_kill_task()

[Johannes Weiner]

From: Johannes Weiner <jweiner@redhat.com>

The memcg argument of oom_kill_task() hasn't been used since 341aea2
'oom-kill: remove boost_dying_task_prio()'.  Kill it.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 mm/oom_kill.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 471dedb..fd9e303 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -423,7 +423,7 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
 }
 
 #define K(x) ((x) << (PAGE_SHIFT-10))
-static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
+static int oom_kill_task(struct task_struct *p)
 {
 	struct task_struct *q;
 	struct mm_struct *mm;
@@ -522,7 +522,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 		}
 	} while_each_thread(p, t);
 
-	return oom_kill_task(victim, mem);
+	return oom_kill_task(victim);
 }
 
 /*
-- 
1.7.6.4

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[patch 2/7] mm: unify remaining mem_cont, mem, etc. variable names to memcg

[Johannes Weiner]

From: Johannes Weiner <jweiner@redhat.com>

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 include/linux/memcontrol.h |   16 ++++++------
 include/linux/oom.h        |    2 +-
 include/linux/rmap.h       |    4 +-
 mm/memcontrol.c            |   52 ++++++++++++++++++++++---------------------
 mm/oom_kill.c              |   38 ++++++++++++++++----------------
 mm/rmap.c                  |   20 ++++++++--------
 mm/swapfile.c              |    9 ++++---
 mm/vmscan.c                |   12 +++++-----
 8 files changed, 78 insertions(+), 75 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 2bf7698..a072ebe 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -54,10 +54,10 @@ extern int mem_cgroup_newpage_charge(struct page *page, struct mm_struct *mm,
 				gfp_t gfp_mask);
 /* for swap handling */
 extern int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
-		struct page *page, gfp_t mask, struct mem_cgroup **ptr);
+		struct page *page, gfp_t mask, struct mem_cgroup **memcgp);
 extern void mem_cgroup_commit_charge_swapin(struct page *page,
-					struct mem_cgroup *ptr);
-extern void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *ptr);
+					struct mem_cgroup *memcg);
+extern void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg);
 
 extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
 					gfp_t gfp_mask);
@@ -98,7 +98,7 @@ extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg);
 
 extern int
 mem_cgroup_prepare_migration(struct page *page,
-	struct page *newpage, struct mem_cgroup **ptr, gfp_t gfp_mask);
+	struct page *newpage, struct mem_cgroup **memcgp, gfp_t gfp_mask);
 extern void mem_cgroup_end_migration(struct mem_cgroup *memcg,
 	struct page *oldpage, struct page *newpage, bool migration_ok);
 
@@ -181,17 +181,17 @@ static inline int mem_cgroup_cache_charge(struct page *page,
 }
 
 static inline int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
-		struct page *page, gfp_t gfp_mask, struct mem_cgroup **ptr)
+		struct page *page, gfp_t gfp_mask, struct mem_cgroup **memcgp)
 {
 	return 0;
 }
 
 static inline void mem_cgroup_commit_charge_swapin(struct page *page,
-					  struct mem_cgroup *ptr)
+					  struct mem_cgroup *memcg)
 {
 }
 
-static inline void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *ptr)
+static inline void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
 {
 }
 
@@ -270,7 +270,7 @@ static inline struct cgroup_subsys_state
 
 static inline int
 mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
-	struct mem_cgroup **ptr, gfp_t gfp_mask)
+	struct mem_cgroup **memcgp, gfp_t gfp_mask)
 {
 	return 0;
 }
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 6f9d04a..552fba9 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -43,7 +43,7 @@ enum oom_constraint {
 extern void compare_swap_oom_score_adj(int old_val, int new_val);
 extern int test_set_oom_score_adj(int new_val);
 
-extern unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
+extern unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
 			const nodemask_t *nodemask, unsigned long totalpages);
 extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
 extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 2148b12..5ee84fb 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -157,7 +157,7 @@ static inline void page_dup_rmap(struct page *page)
  * Called from mm/vmscan.c to handle paging out
  */
 int page_referenced(struct page *, int is_locked,
-			struct mem_cgroup *cnt, unsigned long *vm_flags);
+			struct mem_cgroup *memcg, unsigned long *vm_flags);
 int page_referenced_one(struct page *, struct vm_area_struct *,
 	unsigned long address, unsigned int *mapcount, unsigned long *vm_flags);
 
@@ -235,7 +235,7 @@ int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
 #define anon_vma_link(vma)	do {} while (0)
 
 static inline int page_referenced(struct page *page, int is_locked,
-				  struct mem_cgroup *cnt,
+				  struct mem_cgroup *memcg,
 				  unsigned long *vm_flags)
 {
 	*vm_flags = 0;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f524660..473b99f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2778,12 +2778,12 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
  */
 int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
 				 struct page *page,
-				 gfp_t mask, struct mem_cgroup **ptr)
+				 gfp_t mask, struct mem_cgroup **memcgp)
 {
 	struct mem_cgroup *memcg;
 	int ret;
 
-	*ptr = NULL;
+	*memcgp = NULL;
 
 	if (mem_cgroup_disabled())
 		return 0;
@@ -2801,27 +2801,27 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
 	memcg = try_get_mem_cgroup_from_page(page);
 	if (!memcg)
 		goto charge_cur_mm;
-	*ptr = memcg;
-	ret = __mem_cgroup_try_charge(NULL, mask, 1, ptr, true);
+	*memcgp = memcg;
+	ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true);
 	css_put(&memcg->css);
 	return ret;
 charge_cur_mm:
 	if (unlikely(!mm))
 		mm = &init_mm;
-	return __mem_cgroup_try_charge(mm, mask, 1, ptr, true);
+	return __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
 }
 
 static void
-__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
+__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
 					enum charge_type ctype)
 {
 	if (mem_cgroup_disabled())
 		return;
-	if (!ptr)
+	if (!memcg)
 		return;
-	cgroup_exclude_rmdir(&ptr->css);
+	cgroup_exclude_rmdir(&memcg->css);
 
-	__mem_cgroup_commit_charge_lrucare(page, ptr, ctype);
+	__mem_cgroup_commit_charge_lrucare(page, memcg, ctype);
 	/*
 	 * Now swap is on-memory. This means this page may be
 	 * counted both as mem and swap....double count.
@@ -2831,21 +2831,22 @@ __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
 	 */
 	if (do_swap_account && PageSwapCache(page)) {
 		swp_entry_t ent = {.val = page_private(page)};
+		struct mem_cgroup *swap_memcg;
 		unsigned short id;
-		struct mem_cgroup *memcg;
 
 		id = swap_cgroup_record(ent, 0);
 		rcu_read_lock();
-		memcg = mem_cgroup_lookup(id);
-		if (memcg) {
+		swap_memcg = mem_cgroup_lookup(id);
+		if (swap_memcg) {
 			/*
 			 * This recorded memcg can be obsolete one. So, avoid
 			 * calling css_tryget
 			 */
-			if (!mem_cgroup_is_root(memcg))
-				res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
-			mem_cgroup_swap_statistics(memcg, false);
-			mem_cgroup_put(memcg);
+			if (!mem_cgroup_is_root(swap_memcg))
+				res_counter_uncharge(&swap_memcg->memsw,
+						     PAGE_SIZE);
+			mem_cgroup_swap_statistics(swap_memcg, false);
+			mem_cgroup_put(swap_memcg);
 		}
 		rcu_read_unlock();
 	}
@@ -2854,13 +2855,14 @@ __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
 	 * So, rmdir()->pre_destroy() can be called while we do this charge.
 	 * In that case, we need to call pre_destroy() again. check it here.
 	 */
-	cgroup_release_and_wakeup_rmdir(&ptr->css);
+	cgroup_release_and_wakeup_rmdir(&memcg->css);
 }
 
-void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
+void mem_cgroup_commit_charge_swapin(struct page *page,
+				     struct mem_cgroup *memcg)
 {
-	__mem_cgroup_commit_charge_swapin(page, ptr,
-					MEM_CGROUP_CHARGE_TYPE_MAPPED);
+	__mem_cgroup_commit_charge_swapin(page, memcg,
+					  MEM_CGROUP_CHARGE_TYPE_MAPPED);
 }
 
 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
@@ -3189,14 +3191,14 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
  * page belongs to.
  */
 int mem_cgroup_prepare_migration(struct page *page,
-	struct page *newpage, struct mem_cgroup **ptr, gfp_t gfp_mask)
+	struct page *newpage, struct mem_cgroup **memcgp, gfp_t gfp_mask)
 {
 	struct mem_cgroup *memcg = NULL;
 	struct page_cgroup *pc;
 	enum charge_type ctype;
 	int ret = 0;
 
-	*ptr = NULL;
+	*memcgp = NULL;
 
 	VM_BUG_ON(PageTransHuge(page));
 	if (mem_cgroup_disabled())
@@ -3247,10 +3249,10 @@ int mem_cgroup_prepare_migration(struct page *page,
 	if (!memcg)
 		return 0;
 
-	*ptr = memcg;
-	ret = __mem_cgroup_try_charge(NULL, gfp_mask, 1, ptr, false);
+	*memcgp = memcg;
+	ret = __mem_cgroup_try_charge(NULL, gfp_mask, 1, memcgp, false);
 	css_put(&memcg->css);/* drop extra refcnt */
-	if (ret || *ptr == NULL) {
+	if (ret || *memcgp == NULL) {
 		if (PageAnon(page)) {
 			lock_page_cgroup(pc);
 			ClearPageCgroupMigration(pc);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index fd9e303..307351e 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -146,7 +146,7 @@ struct task_struct *find_lock_task_mm(struct task_struct *p)
 
 /* return true if the task is not adequate as candidate victim task. */
 static bool oom_unkillable_task(struct task_struct *p,
-		const struct mem_cgroup *mem, const nodemask_t *nodemask)
+		const struct mem_cgroup *memcg, const nodemask_t *nodemask)
 {
 	if (is_global_init(p))
 		return true;
@@ -154,7 +154,7 @@ static bool oom_unkillable_task(struct task_struct *p,
 		return true;
 
 	/* When mem_cgroup_out_of_memory() and p is not member of the group */
-	if (mem && !task_in_mem_cgroup(p, mem))
+	if (memcg && !task_in_mem_cgroup(p, memcg))
 		return true;
 
 	/* p may not have freeable memory in nodemask */
@@ -173,12 +173,12 @@ static bool oom_unkillable_task(struct task_struct *p,
  * predictable as possible.  The goal is to return the highest value for the
  * task consuming the most memory to avoid subsequent oom failures.
  */
-unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
+unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
 		      const nodemask_t *nodemask, unsigned long totalpages)
 {
 	int points;
 
-	if (oom_unkillable_task(p, mem, nodemask))
+	if (oom_unkillable_task(p, memcg, nodemask))
 		return 0;
 
 	p = find_lock_task_mm(p);
@@ -297,7 +297,7 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
  * (not docbooked, we don't want this one cluttering up the manual)
  */
 static struct task_struct *select_bad_process(unsigned int *ppoints,
-		unsigned long totalpages, struct mem_cgroup *mem,
+		unsigned long totalpages, struct mem_cgroup *memcg,
 		const nodemask_t *nodemask)
 {
 	struct task_struct *g, *p;
@@ -309,7 +309,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
 
 		if (p->exit_state)
 			continue;
-		if (oom_unkillable_task(p, mem, nodemask))
+		if (oom_unkillable_task(p, memcg, nodemask))
 			continue;
 
 		/*
@@ -353,7 +353,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
 			}
 		}
 
-		points = oom_badness(p, mem, nodemask, totalpages);
+		points = oom_badness(p, memcg, nodemask, totalpages);
 		if (points > *ppoints) {
 			chosen = p;
 			*ppoints = points;
@@ -376,14 +376,14 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
  *
  * Call with tasklist_lock read-locked.
  */
-static void dump_tasks(const struct mem_cgroup *mem, const nodemask_t *nodemask)
+static void dump_tasks(const struct mem_cgroup *memcg, const nodemask_t *nodemask)
 {
 	struct task_struct *p;
 	struct task_struct *task;
 
 	pr_info("[ pid ]   uid  tgid total_vm      rss cpu oom_adj oom_score_adj name\n");
 	for_each_process(p) {
-		if (oom_unkillable_task(p, mem, nodemask))
+		if (oom_unkillable_task(p, memcg, nodemask))
 			continue;
 
 		task = find_lock_task_mm(p);
@@ -406,7 +406,7 @@ static void dump_tasks(const struct mem_cgroup *mem, const nodemask_t *nodemask)
 }
 
 static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
-			struct mem_cgroup *mem, const nodemask_t *nodemask)
+			struct mem_cgroup *memcg, const nodemask_t *nodemask)
 {
 	task_lock(current);
 	pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
@@ -416,10 +416,10 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
 	cpuset_print_task_mems_allowed(current);
 	task_unlock(current);
 	dump_stack();
-	mem_cgroup_print_oom_info(mem, p);
+	mem_cgroup_print_oom_info(memcg, p);
 	show_mem(SHOW_MEM_FILTER_NODES);
 	if (sysctl_oom_dump_tasks)
-		dump_tasks(mem, nodemask);
+		dump_tasks(memcg, nodemask);
 }
 
 #define K(x) ((x) << (PAGE_SHIFT-10))
@@ -473,7 +473,7 @@ static int oom_kill_task(struct task_struct *p)
 
 static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 			    unsigned int points, unsigned long totalpages,
-			    struct mem_cgroup *mem, nodemask_t *nodemask,
+			    struct mem_cgroup *memcg, nodemask_t *nodemask,
 			    const char *message)
 {
 	struct task_struct *victim = p;
@@ -482,7 +482,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 	unsigned int victim_points = 0;
 
 	if (printk_ratelimit())
-		dump_header(p, gfp_mask, order, mem, nodemask);
+		dump_header(p, gfp_mask, order, memcg, nodemask);
 
 	/*
 	 * If the task is already exiting, don't alarm the sysadmin or kill
@@ -513,7 +513,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 			/*
 			 * oom_badness() returns 0 if the thread is unkillable
 			 */
-			child_points = oom_badness(child, mem, nodemask,
+			child_points = oom_badness(child, memcg, nodemask,
 								totalpages);
 			if (child_points > victim_points) {
 				victim = child;
@@ -550,7 +550,7 @@ static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
 }
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
-void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
+void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask)
 {
 	unsigned long limit;
 	unsigned int points = 0;
@@ -567,14 +567,14 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
 	}
 
 	check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
-	limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;
+	limit = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT;
 	read_lock(&tasklist_lock);
 retry:
-	p = select_bad_process(&points, limit, mem, NULL);
+	p = select_bad_process(&points, limit, memcg, NULL);
 	if (!p || PTR_ERR(p) == -1UL)
 		goto out;
 
-	if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, NULL,
+	if (oom_kill_process(p, gfp_mask, 0, points, limit, memcg, NULL,
 				"Memory cgroup out of memory"))
 		goto retry;
 out:
diff --git a/mm/rmap.c b/mm/rmap.c
index a4fd368..c13791b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -728,7 +728,7 @@ out:
 }
 
 static int page_referenced_anon(struct page *page,
-				struct mem_cgroup *mem_cont,
+				struct mem_cgroup *memcg,
 				unsigned long *vm_flags)
 {
 	unsigned int mapcount;
@@ -751,7 +751,7 @@ static int page_referenced_anon(struct page *page,
 		 * counting on behalf of references from different
 		 * cgroups
 		 */
-		if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
+		if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
 			continue;
 		referenced += page_referenced_one(page, vma, address,
 						  &mapcount, vm_flags);
@@ -766,7 +766,7 @@ static int page_referenced_anon(struct page *page,
 /**
  * page_referenced_file - referenced check for object-based rmap
  * @page: the page we're checking references on.
- * @mem_cont: target memory controller
+ * @memcg: target memory control group
  * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
  *
  * For an object-based mapped page, find all the places it is mapped and
@@ -777,7 +777,7 @@ static int page_referenced_anon(struct page *page,
  * This function is only called from page_referenced for object-based pages.
  */
 static int page_referenced_file(struct page *page,
-				struct mem_cgroup *mem_cont,
+				struct mem_cgroup *memcg,
 				unsigned long *vm_flags)
 {
 	unsigned int mapcount;
@@ -819,7 +819,7 @@ static int page_referenced_file(struct page *page,
 		 * counting on behalf of references from different
 		 * cgroups
 		 */
-		if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
+		if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
 			continue;
 		referenced += page_referenced_one(page, vma, address,
 						  &mapcount, vm_flags);
@@ -835,7 +835,7 @@ static int page_referenced_file(struct page *page,
  * page_referenced - test if the page was referenced
  * @page: the page to test
  * @is_locked: caller holds lock on the page
- * @mem_cont: target memory controller
+ * @memcg: target memory cgroup
  * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
  *
  * Quick test_and_clear_referenced for all mappings to a page,
@@ -843,7 +843,7 @@ static int page_referenced_file(struct page *page,
  */
 int page_referenced(struct page *page,
 		    int is_locked,
-		    struct mem_cgroup *mem_cont,
+		    struct mem_cgroup *memcg,
 		    unsigned long *vm_flags)
 {
 	int referenced = 0;
@@ -859,13 +859,13 @@ int page_referenced(struct page *page,
 			}
 		}
 		if (unlikely(PageKsm(page)))
-			referenced += page_referenced_ksm(page, mem_cont,
+			referenced += page_referenced_ksm(page, memcg,
 								vm_flags);
 		else if (PageAnon(page))
-			referenced += page_referenced_anon(page, mem_cont,
+			referenced += page_referenced_anon(page, memcg,
 								vm_flags);
 		else if (page->mapping)
-			referenced += page_referenced_file(page, mem_cont,
+			referenced += page_referenced_file(page, memcg,
 								vm_flags);
 		if (we_locked)
 			unlock_page(page);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index b1cd120..c2e1312 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -847,12 +847,13 @@ unsigned int count_swap_pages(int type, int free)
 static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 		unsigned long addr, swp_entry_t entry, struct page *page)
 {
-	struct mem_cgroup *ptr;
+	struct mem_cgroup *memcg;
 	spinlock_t *ptl;
 	pte_t *pte;
 	int ret = 1;
 
-	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) {
+	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page,
+					 GFP_KERNEL, &memcg)) {
 		ret = -ENOMEM;
 		goto out_nolock;
 	}
@@ -860,7 +861,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
 		if (ret > 0)
-			mem_cgroup_cancel_charge_swapin(ptr);
+			mem_cgroup_cancel_charge_swapin(memcg);
 		ret = 0;
 		goto out;
 	}
@@ -871,7 +872,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 	set_pte_at(vma->vm_mm, addr, pte,
 		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
 	page_add_anon_rmap(page, vma, addr);
-	mem_cgroup_commit_charge_swapin(page, ptr);
+	mem_cgroup_commit_charge_swapin(page, memcg);
 	swap_free(entry);
 	/*
 	 * Move the page to the active list so it is not
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 21ce3cb..855c450 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2387,7 +2387,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 
-unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
+unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
 						gfp_t gfp_mask, bool noswap,
 						struct zone *zone,
 						unsigned long *nr_scanned)
@@ -2399,10 +2399,10 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 		.may_unmap = 1,
 		.may_swap = !noswap,
 		.order = 0,
-		.target_mem_cgroup = mem,
+		.target_mem_cgroup = memcg,
 	};
 	struct mem_cgroup_zone mz = {
-		.mem_cgroup = mem,
+		.mem_cgroup = memcg,
 		.zone = zone,
 	};
 
@@ -2428,7 +2428,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 	return sc.nr_reclaimed;
 }
 
-unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
+unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 					   gfp_t gfp_mask,
 					   bool noswap)
 {
@@ -2441,7 +2441,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 		.may_swap = !noswap,
 		.nr_to_reclaim = SWAP_CLUSTER_MAX,
 		.order = 0,
-		.target_mem_cgroup = mem_cont,
+		.target_mem_cgroup = memcg,
 		.nodemask = NULL, /* we don't care the placement */
 		.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
 				(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
@@ -2455,7 +2455,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 	 * take care of from where we get pages. So the node where we start the
 	 * scan does not need to be the current node.
 	 */
-	nid = mem_cgroup_select_victim_node(mem_cont);
+	nid = mem_cgroup_select_victim_node(memcg);
 
 	zonelist = NODE_DATA(nid)->node_zonelists;
 
-- 
1.7.6.4

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[patch 3/7] mm: memcg: clean up fault accounting

[Johannes Weiner]

From: Johannes Weiner <jweiner@redhat.com>

The fault accounting functions have a single, memcg-internal user, so
they don't need to be global.  In fact, their one-line bodies can be
directly folded into the caller.  And since faults happen one at a
time, use this_cpu_inc() directly instead of this_cpu_add(foo, 1).

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Balbir Singh <bsingharora@gmail.com>
---
 mm/memcontrol.c |   14 ++------------
 1 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 473b99f..d825af9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -589,16 +589,6 @@ static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
 	this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
 }
 
-void mem_cgroup_pgfault(struct mem_cgroup *memcg, int val)
-{
-	this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT], val);
-}
-
-void mem_cgroup_pgmajfault(struct mem_cgroup *memcg, int val)
-{
-	this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT], val);
-}
-
 static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
 					    enum mem_cgroup_events_index idx)
 {
@@ -913,10 +903,10 @@ void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
 
 	switch (idx) {
 	case PGMAJFAULT:
-		mem_cgroup_pgmajfault(memcg, 1);
+		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
 		break;
 	case PGFAULT:
-		mem_cgroup_pgfault(memcg, 1);
+		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
 		break;
 	default:
 		BUG();
-- 
1.7.6.4

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[patch 4/7] mm: memcg: lookup_page_cgroup (almost) never returns NULL

[Johannes Weiner]

From: Johannes Weiner <jweiner@redhat.com>

Pages have their corresponding page_cgroup descriptors set up before
they are used in userspace, and thus managed by a memory cgroup.

The only time where lookup_page_cgroup() can return NULL is in the
CONFIG_DEBUG_VM-only page sanity checking code that executes while
feeding pages into the page allocator for the first time.

Remove the NULL checks against lookup_page_cgroup() results from all
callsites where we know that corresponding page_cgroup descriptors
must be allocated, and add a comment to the callsite that actually
does have to check the return value.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 mm/memcontrol.c |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d825af9..8ccb342 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1894,9 +1894,6 @@ void mem_cgroup_update_page_stat(struct page *page,
 	bool need_unlock = false;
 	unsigned long uninitialized_var(flags);
 
-	if (unlikely(!pc))
-		return;
-
 	rcu_read_lock();
 	memcg = pc->mem_cgroup;
 	if (unlikely(!memcg || !PageCgroupUsed(pc)))
@@ -2669,8 +2666,6 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
 	}
 
 	pc = lookup_page_cgroup(page);
-	BUG_ON(!pc); /* XXX: remove this and move pc lookup into commit */
-
 	ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
 	if (ret || !memcg)
 		return ret;
@@ -2942,7 +2937,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
 	 * Check if our page_cgroup is valid
 	 */
 	pc = lookup_page_cgroup(page);
-	if (unlikely(!pc || !PageCgroupUsed(pc)))
+	if (unlikely(!PageCgroupUsed(pc)))
 		return NULL;
 
 	lock_page_cgroup(pc);
@@ -3326,6 +3321,10 @@ static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
 	struct page_cgroup *pc;
 
 	pc = lookup_page_cgroup(page);
+	/*
+	 * Can be NULL while feeding pages into the page allocator for
+	 * the first time, i.e. during boot or memory hotplug.
+	 */
 	if (likely(pc) && PageCgroupUsed(pc))
 		return pc;
 	return NULL;
-- 
1.7.6.4

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[patch 5/7] mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary

[Johannes Weiner]

lookup_page_cgroup() is usually used only against pages that are used
in userspace.

The exception is the CONFIG_DEBUG_VM-only memcg check from the page
allocator: it can run on pages without page_cgroup descriptors
allocated when the pages are fed into the page allocator for the first
time during boot or memory hotplug.

Include the array check only when CONFIG_DEBUG_VM is set and save the
unnecessary check in production kernels.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/page_cgroup.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index a14655d..58405ca 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -28,9 +28,16 @@ struct page_cgroup *lookup_page_cgroup(struct page *page)
 	struct page_cgroup *base;
 
 	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The sanity checks the page allocator does upon freeing a
+	 * page can reach here before the page_cgroup arrays are
+	 * allocated when feeding a range of pages to the allocator
+	 * for the first time during bootup or memory hotplug.
+	 */
 	if (unlikely(!base))
 		return NULL;
-
+#endif
 	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
 	return base + offset;
 }
@@ -87,9 +94,16 @@ struct page_cgroup *lookup_page_cgroup(struct page *page)
 {
 	unsigned long pfn = page_to_pfn(page);
 	struct mem_section *section = __pfn_to_section(pfn);
-
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The sanity checks the page allocator does upon freeing a
+	 * page can reach here before the page_cgroup arrays are
+	 * allocated when feeding a range of pages to the allocator
+	 * for the first time during bootup or memory hotplug.
+	 */
 	if (!section->page_cgroup)
 		return NULL;
+#endif
 	return section->page_cgroup + pfn;
 }
 
-- 
1.7.6.4

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Re: [patch 5/7] mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary

[Michal Hocko]

On Tue 29-11-11 11:52:03, Johannes Weiner wrote:
> lookup_page_cgroup() is usually used only against pages that are used
> in userspace.
> 
> The exception is the CONFIG_DEBUG_VM-only memcg check from the page
> allocator: it can run on pages without page_cgroup descriptors
> allocated when the pages are fed into the page allocator for the first
> time during boot or memory hotplug.
> 
> Include the array check only when CONFIG_DEBUG_VM is set and save the
> unnecessary check in production kernels.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

I was thinking about adding BUG_ON before dereferencing but this
is questionable because NULL ptr dereference will provide the same
information except sec. guys might be alerted.

I like the smaller code more of course.

Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
>  mm/page_cgroup.c |   18 ++++++++++++++++--
>  1 files changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
> index a14655d..58405ca 100644
> --- a/mm/page_cgroup.c
> +++ b/mm/page_cgroup.c
> @@ -28,9 +28,16 @@ struct page_cgroup *lookup_page_cgroup(struct page *page)
>  	struct page_cgroup *base;
>  
>  	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
> +#ifdef CONFIG_DEBUG_VM
> +	/*
> +	 * The sanity checks the page allocator does upon freeing a
> +	 * page can reach here before the page_cgroup arrays are
> +	 * allocated when feeding a range of pages to the allocator
> +	 * for the first time during bootup or memory hotplug.
> +	 */
>  	if (unlikely(!base))
>  		return NULL;
> -
> +#endif
>  	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
>  	return base + offset;
>  }
> @@ -87,9 +94,16 @@ struct page_cgroup *lookup_page_cgroup(struct page *page)
>  {
>  	unsigned long pfn = page_to_pfn(page);
>  	struct mem_section *section = __pfn_to_section(pfn);
> -
> +#ifdef CONFIG_DEBUG_VM
> +	/*
> +	 * The sanity checks the page allocator does upon freeing a
> +	 * page can reach here before the page_cgroup arrays are
> +	 * allocated when feeding a range of pages to the allocator
> +	 * for the first time during bootup or memory hotplug.
> +	 */
>  	if (!section->page_cgroup)
>  		return NULL;
> +#endif
>  	return section->page_cgroup + pfn;
>  }
>  
> -- 
> 1.7.6.4
> 

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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Re: [patch 5/7] mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary

[KAMEZAWA Hiroyuki]

On Tue, 29 Nov 2011 11:52:03 +0100
Johannes Weiner <hannes@cmpxchg.org> wrote:

> lookup_page_cgroup() is usually used only against pages that are used
> in userspace.
> 
> The exception is the CONFIG_DEBUG_VM-only memcg check from the page
> allocator: it can run on pages without page_cgroup descriptors
> allocated when the pages are fed into the page allocator for the first
> time during boot or memory hotplug.
> 
> Include the array check only when CONFIG_DEBUG_VM is set and save the
> unnecessary check in production kernels.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


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[patch 6/7] mm: memcg: remove unneeded checks from newpage_charge()

[Johannes Weiner]

From: Johannes Weiner <jweiner@redhat.com>

All callsites pass in freshly allocated pages and a valid mm.  As a
result, all checks pertaining the page's mapcount, page->mapping or
the fallback to init_mm are unneeded.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 mm/memcontrol.c |   16 ++++------------
 1 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8ccb342..f5aa1b8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2679,19 +2679,11 @@ int mem_cgroup_newpage_charge(struct page *page,
 {
 	if (mem_cgroup_disabled())
 		return 0;
-	/*
-	 * If already mapped, we don't have to account.
-	 * If page cache, page->mapping has address_space.
-	 * But page->mapping may have out-of-use anon_vma pointer,
-	 * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
-	 * is NULL.
-  	 */
-	if (page_mapped(page) || (page->mapping && !PageAnon(page)))
-		return 0;
-	if (unlikely(!mm))
-		mm = &init_mm;
+	VM_BUG_ON(page_mapped(page));
+	VM_BUG_ON(page->mapping && !PageAnon(page));
+	VM_BUG_ON(!mm);
 	return mem_cgroup_charge_common(page, mm, gfp_mask,
-				MEM_CGROUP_CHARGE_TYPE_MAPPED);
+					MEM_CGROUP_CHARGE_TYPE_MAPPED);
 }
 
 static void
-- 
1.7.6.4

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[patch 7/7] mm: memcg: remove unneeded checks from uncharge_page()

[Johannes Weiner]

From: Johannes Weiner <jweiner@redhat.com>

mem_cgroup_uncharge_page() is only called on either freshly allocated
pages without page->mapping or on rmapped PageAnon() pages.  There is
no need to check for a page->mapping that is not an anon_vma.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 mm/memcontrol.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f5aa1b8..468a5a4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2992,8 +2992,7 @@ void mem_cgroup_uncharge_page(struct page *page)
 	/* early check. */
 	if (page_mapped(page))
 		return;
-	if (page->mapping && !PageAnon(page))
-		return;
+	VM_BUG_ON(page->mapping && !PageAnon(page));
 	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
 }
 
-- 
1.7.6.4

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