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    SubjectRe: [LKP] [rcu] f836ea2ec9: BUG:unable_to_handle_kernel
    On Thu, Mar 21, 2019 at 04:49:37PM +0800, kernel test robot wrote:
    > FYI, we noticed the following commit (built with gcc-7):
    >
    > commit: f836ea2ec954a20af25861e68075ad743be046f4 ("rcu: Forbid DEFINE{,_STATIC}_SRCU() from modules")
    > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2019.03.18a

    This commit has been replaced by eb89abcb3073 ("rcu: Forbid
    DEFINE{,_STATIC}_SRCU() from modules"), but this did locate an otherwise
    mostly latent bug, the fix for which is shown below.

    So thank you again. ;-)

    Thanx, Paul

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

    commit 6534d5b0f24accd71620873980ba5a14aa85e898
    Author: Paul E. McKenney <paulmck@linux.ibm.com>
    Date: Thu Mar 21 09:27:28 2019 -0700

    rcutorture: Fix cleanup path for invalid torture_type strings

    If the specified rcutorture.torture_type is not in the rcu_torture_init()
    function's torture_ops[] array, rcutorture prints some console messages
    and then invokes rcu_torture_cleanup() to set state so that a future
    torture test can run. However, rcu_torture_cleanup() also attempts to
    end the test that didn't actually start, and in doing so relies on the
    value of cur_ops, a value that is not particularly relevant in this case.
    This can result in confusing output or even follow-on failures due to
    attempts to use facilities that have not been properly initialized.

    This commit therefore sets the value of cur_ops to NULL in this case
    and inserts a check near the beginning of rcu_torture_cleanup(),
    thus avoiding relying on an irrelevant cur_ops value.

    Reported-by: kernel test robot <rong.a.chen@intel.com>
    Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

    diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
    index 7086caa743c7..af31ddee7b36 100644
    --- a/kernel/rcu/rcutorture.c
    +++ b/kernel/rcu/rcutorture.c
    @@ -2101,6 +2101,10 @@ rcu_torture_cleanup(void)
    cur_ops->cb_barrier();
    return;
    }
    + if (!cur_ops) {
    + torture_cleanup_end();
    + return;
    + }

    rcu_torture_barrier_cleanup();
    torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
    @@ -2281,6 +2285,7 @@ rcu_torture_init(void)
    pr_cont("\n");
    WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
    firsterr = -EINVAL;
    + cur_ops = NULL;
    goto unwind;
    }
    if (cur_ops->fqs == NULL && fqs_duration != 0) {
    \
     
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      Last update: 2019-03-21 17:43    [W:2.710 / U:0.532 seconds]
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