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    Subject[PATCH 4.16 069/279] proc: fix /proc/loadavg regression
    Date
    4.16-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Alexey Dobriyan <adobriyan@gmail.com>

    [ Upstream commit 9a1015b32faa7cebfe19663c886b0cfe90be1d49 ]

    Commit 95846ecf9dac ("pid: replace pid bitmap implementation with IDR
    API") changed last field of /proc/loadavg (last pid allocated) to be off
    by one:

    # unshare -p -f --mount-proc cat /proc/loadavg
    0.00 0.00 0.00 1/60 2 <===

    It should be 1 after first fork into pid namespace.

    This is formally a regression but given how useless this field is I
    don't think anyone is affected.

    Bug was found by /proc testsuite!

    Link: http://lkml.kernel.org/r/20180413175408.GA27246@avx2
    Fixes: 95846ecf9dac508 ("pid: replace pid bitmap implementation with IDR API")
    Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Cc: Gargi Sharma <gs051095@gmail.com>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/powerpc/platforms/cell/spufs/sched.c | 2 +-
    fs/proc/loadavg.c | 2 +-
    2 files changed, 2 insertions(+), 2 deletions(-)

    --- a/arch/powerpc/platforms/cell/spufs/sched.c
    +++ b/arch/powerpc/platforms/cell/spufs/sched.c
    @@ -1093,7 +1093,7 @@ static int show_spu_loadavg(struct seq_f
    LOAD_INT(c), LOAD_FRAC(c),
    count_active_contexts(),
    atomic_read(&nr_spu_contexts),
    - idr_get_cursor(&task_active_pid_ns(current)->idr));
    + idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
    return 0;
    }

    --- a/fs/proc/loadavg.c
    +++ b/fs/proc/loadavg.c
    @@ -24,7 +24,7 @@ static int loadavg_proc_show(struct seq_
    LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
    LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]),
    nr_running(), nr_threads,
    - idr_get_cursor(&task_active_pid_ns(current)->idr));
    + idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
    return 0;
    }


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