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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-02-28 10:34:54 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-05-15 10:27:11 -0700 |
| commit | ef12620626e4e6a062acd9701d1d3429b2356773 (patch) | |
| tree | c71cd47c517e568645b766067da600bcaf34a612 | |
| parent | be01b4cab118e7a2d9747c71b3bef8f28fdda193 (diff) | |
| download | linux-ef12620626e4e6a062acd9701d1d3429b2356773.tar.gz linux-ef12620626e4e6a062acd9701d1d3429b2356773.tar.bz2 linux-ef12620626e4e6a062acd9701d1d3429b2356773.zip | |
rcu: Don't allocate rcu_nocb_mask if no one needs it
Commit 44c65ff2e3b0 ("rcu: Eliminate NOCBs CPU-state Kconfig options")
made allocation of rcu_nocb_mask depend only on the rcu_nocbs=,
nohz_full=, or isolcpus= kernel boot parameters. However, it failed
to change the initial value of rcu_init_nohz()'s local variable
need_rcu_nocb_mask to false, which can result in useless allocation
of an all-zero rcu_nocb_mask. This commit therefore fixes this bug by
changing the initial value of need_rcu_nocb_mask to false.
While we are in the area, also correct the error message that is printed
when someone specifies that can-never-exist CPUs should be NOCBs CPUs.
Reported-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Byungchul Park <byungchul.park@lge.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 6c5df18bbf2f..3566e4f6dfcc 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2283,7 +2283,7 @@ static void do_nocb_deferred_wakeup(struct rcu_data *rdp) void __init rcu_init_nohz(void) { int cpu; - bool need_rcu_nocb_mask = true; + bool need_rcu_nocb_mask = false; struct rcu_state *rsp; #if defined(CONFIG_NO_HZ_FULL) @@ -2306,7 +2306,7 @@ void __init rcu_init_nohz(void) #endif /* #if defined(CONFIG_NO_HZ_FULL) */ if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) { - pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n"); + pr_info("\tNote: kernel parameter 'rcu_nocbs=', 'nohz_full', or 'isolcpus=' contains nonexistent CPUs.\n"); cpumask_and(rcu_nocb_mask, cpu_possible_mask, rcu_nocb_mask); } |