mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat()

sync_mm_rss() can only be used for current to avoid race conditions in
iterating and clearing its per-task counters.  Remove the task argument
for it and its helper function, __sync_task_rss_stat(), to avoid thinking
it can be used safely for anything other than current.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 14 insertions, 14 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 3908544f5d18..6ed164d20d7d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -824,7 +824,7 @@ static int exec_mmap(struct mm_struct *mm)
         /* Notify parent that we're no longer interested in the old VM */
         tsk = current;
         old_mm = current->mm;
-        sync_mm_rss(tsk, old_mm);
+        sync_mm_rss(old_mm);
         mm_release(tsk, old_mm);
 
         if (old_mm) {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index df17ff23d50e..ce2b2a3b2876 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1131,9 +1131,9 @@ static inline void setmax_mm_hiwater_rss(unsigned long *maxrss,
 }
 
 #if defined(SPLIT_RSS_COUNTING)
-void sync_mm_rss(struct task_struct *task, struct mm_struct *mm);
+void sync_mm_rss(struct mm_struct *mm);
 #else
-static inline void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
+static inline void sync_mm_rss(struct mm_struct *mm)
 {
 }
 #endif
diff --git a/kernel/exit.c b/kernel/exit.c
index 0ed15fed579f..d26acd3c1e2e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -934,7 +934,7 @@ void do_exit(long code)
         acct_update_integrals(tsk);
         /* sync mm's RSS info before statistics gathering */
         if (tsk->mm)
-                sync_mm_rss(tsk, tsk->mm);
+                sync_mm_rss(tsk->mm);
         group_dead = atomic_dec_and_test(&tsk->signal->live);
         if (group_dead) {
                 hrtimer_cancel(&tsk->signal->real_timer);
diff --git a/mm/memory.c b/mm/memory.c
index a5de734e14a7..2d27239ce4dd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -125,17 +125,17 @@ core_initcall(init_zero_pfn);
 
 #if defined(SPLIT_RSS_COUNTING)
 
-static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
+static void __sync_task_rss_stat(struct mm_struct *mm)
 {
         int i;
 
         for (i = 0; i < NR_MM_COUNTERS; i++) {
-                if (task->rss_stat.count[i]) {
-                        add_mm_counter(mm, i, task->rss_stat.count[i]);
-                        task->rss_stat.count[i] = 0;
+                if (current->rss_stat.count[i]) {
+                        add_mm_counter(mm, i, current->rss_stat.count[i]);
+                        current->rss_stat.count[i] = 0;
                 }
         }
-        task->rss_stat.events = 0;
+        current->rss_stat.events = 0;
 }
 
 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
@@ -157,12 +157,12 @@ static void check_sync_rss_stat(struct task_struct *task)
         if (unlikely(task != current))
                 return;
         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
-                __sync_task_rss_stat(task, task->mm);
+                __sync_task_rss_stat(task->mm);
 }
 
-void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
+void sync_mm_rss(struct mm_struct *mm)
 {
-        __sync_task_rss_stat(task, mm);
+        __sync_task_rss_stat(mm);
 }
 #else /* SPLIT_RSS_COUNTING */
 
@@ -643,7 +643,7 @@ static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
         int i;
 
         if (current->mm == mm)
-                sync_mm_rss(current, mm);
+                sync_mm_rss(mm);
         for (i = 0; i < NR_MM_COUNTERS; i++)
                 if (rss[i])
                         add_mm_counter(mm, i, rss[i]);
diff --git a/mm/mmu_context.c b/mm/mmu_context.c
index cf332bc0080a..3dcfaf4ed355 100644
--- a/mm/mmu_context.c
+++ b/mm/mmu_context.c
@@ -53,7 +53,7 @@ void unuse_mm(struct mm_struct *mm)
         struct task_struct *tsk = current;
 
         task_lock(tsk);
-        sync_mm_rss(tsk, mm);
+        sync_mm_rss(mm);
         tsk->mm = NULL;
         /* active_mm is still 'mm' */
         enter_lazy_tlb(mm, tsk);