[PATCH v3] mlock: fix mlock count can not decrease in race condition

Kefeng reported that when running the follow test, the mlock count in meminfo will increases permanently: [1] testcase linux:~ # cat test_mlockal grep Mlocked /proc/meminfo for j in `seq 0 10` do for i in `seq 4 15` do ./p_mlockall >> log & done

[PATCH v3] mlock: fix mlock count can not decrease in race condition

Kefeng reported that when running the follow test, the mlock count in meminfo will increases permanently: [1] testcase linux:~ # cat test_mlockal grep Mlocked /proc/meminfo for j in `seq 0 10` do for i in `seq 4 15` do ./p_mlockall >> log & done