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Subject[patch 1/2] 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>
---
fs/exec.c | 2 +-
include/linux/mm.h | 4 ++--
kernel/exit.c | 2 +-
mm/memory.c | 18 +++++++++---------
mm/mmu_context.c | 2 +-
5 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -822,7 +822,7 @@ 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
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1127,9 +1127,9 @@ 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
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -953,7 +953,7 @@ 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
--- 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)
@@ -157,7 +157,7 @@ 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);
}

unsigned long get_mm_counter(struct mm_struct *mm, int member)
@@ -178,9 +178,9 @@ unsigned long get_mm_counter(struct mm_struct *mm, int member)
return (unsigned long)val;
}

-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 */

@@ -661,7 +661,7 @@ 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
--- 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);

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