memcg: res_counter_read_u64(): fix potential races on 32-bit machines
res_counter_read_u64 reads u64 value without lock. It's dangerous in a
32bit environment. Add locking.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index c7eaa37..34683ef 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -126,10 +126,24 @@
pos, buf, s - buf);
}
+#if BITS_PER_LONG == 32
+u64 res_counter_read_u64(struct res_counter *counter, int member)
+{
+ unsigned long flags;
+ u64 ret;
+
+ spin_lock_irqsave(&counter->lock, flags);
+ ret = *res_counter_member(counter, member);
+ spin_unlock_irqrestore(&counter->lock, flags);
+
+ return ret;
+}
+#else
u64 res_counter_read_u64(struct res_counter *counter, int member)
{
return *res_counter_member(counter, member);
}
+#endif
int res_counter_memparse_write_strategy(const char *buf,
unsigned long long *res)