lkml.org 
[lkml]   [2021]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.10 436/593] rcu: Invoke rcu_spawn_core_kthreads() from rcu_spawn_gp_kthread()
    Date
    From: Paul E. McKenney <paulmck@kernel.org>

    [ Upstream commit 8e4b1d2bc198e34b48fc7cc3a3c5a2fcb269e271 ]

    Currently, rcu_spawn_core_kthreads() is invoked via an early_initcall(),
    which works, except that rcu_spawn_gp_kthread() is also invoked via an
    early_initcall() and rcu_spawn_core_kthreads() relies on adjustments to
    kthread_prio that are carried out by rcu_spawn_gp_kthread(). There is
    no guaranttee of ordering among early_initcall() handlers, and thus no
    guarantee that kthread_prio will be properly checked and range-limited
    at the time that rcu_spawn_core_kthreads() needs it.

    In most cases, this bug is harmless. After all, the only reason that
    rcu_spawn_gp_kthread() adjusts the value of kthread_prio is if the user
    specified a nonsensical value for this boot parameter, which experience
    indicates is rare.

    Nevertheless, a bug is a bug. This commit therefore causes the
    rcu_spawn_core_kthreads() function to be invoked directly from
    rcu_spawn_gp_kthread() after any needed adjustments to kthread_prio have
    been carried out.

    Fixes: 48d07c04b4cc ("rcu: Enable elimination of Tree-RCU softirq processing")
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/rcu/tree.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
    index 61e250cdd7c9..45b60e997461 100644
    --- a/kernel/rcu/tree.c
    +++ b/kernel/rcu/tree.c
    @@ -2837,7 +2837,6 @@ static int __init rcu_spawn_core_kthreads(void)
    "%s: Could not start rcuc kthread, OOM is now expected behavior\n", __func__);
    return 0;
    }
    -early_initcall(rcu_spawn_core_kthreads);

    /*
    * Handle any core-RCU processing required by a call_rcu() invocation.
    @@ -4273,6 +4272,7 @@ static int __init rcu_spawn_gp_kthread(void)
    wake_up_process(t);
    rcu_spawn_nocb_kthreads();
    rcu_spawn_boost_kthreads();
    + rcu_spawn_core_kthreads();
    return 0;
    }
    early_initcall(rcu_spawn_gp_kthread);
    --
    2.30.2


    \
     
     \ /
      Last update: 2021-07-12 09:40    [W:4.039 / U:0.040 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site