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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-07-25 11:21:47 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-09-16 10:07:59 -0700 |
| commit | f4579fc57cf4244057b713b1f73f4dc9f0b11e97 (patch) | |
| tree | 7c682f8da323a07e5a6d63ad4ff87cc1baf34e73 /init | |
| parent | 11ed7f934cb807f26da09547b5946c2e534d1dac (diff) | |
| download | lwn-f4579fc57cf4244057b713b1f73f4dc9f0b11e97.tar.gz lwn-f4579fc57cf4244057b713b1f73f4dc9f0b11e97.zip | |
rcu: Fix attempt to avoid unsolicited offloading of callbacks
Commit b58cc46c5f6b (rcu: Don't offload callbacks unless specifically
requested) failed to adjust the callback lists of the CPUs that are
known to be no-CBs CPUs only because they are also nohz_full= CPUs.
This failure can result in callbacks that are posted during early boot
getting stranded on nxtlist for CPUs whose no-CBs property becomes
apparent late, and there can also be spurious warnings about offline
CPUs posting callbacks.
This commit fixes these problems by adding an early-boot rcu_init_nohz()
that properly initializes the no-CBs CPUs.
Note that kernels built with CONFIG_RCU_NOCB_CPU_ALL=y or with
CONFIG_RCU_NOCB_CPU=n do not exhibit this bug. Neither do kernels
booted without the nohz_full= boot parameter.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 4 | ||||
| -rw-r--r-- | init/main.c | 1 |
2 files changed, 3 insertions, 2 deletions
diff --git a/init/Kconfig b/init/Kconfig index e84c6423a2e5..64ee4d967786 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -737,7 +737,7 @@ choice config RCU_NOCB_CPU_NONE bool "No build_forced no-CBs CPUs" - depends on RCU_NOCB_CPU && !NO_HZ_FULL_ALL + depends on RCU_NOCB_CPU help This option does not force any of the CPUs to be no-CBs CPUs. Only CPUs designated by the rcu_nocbs= boot parameter will be @@ -751,7 +751,7 @@ config RCU_NOCB_CPU_NONE config RCU_NOCB_CPU_ZERO bool "CPU 0 is a build_forced no-CBs CPU" - depends on RCU_NOCB_CPU && !NO_HZ_FULL_ALL + depends on RCU_NOCB_CPU help This option forces CPU 0 to be a no-CBs CPU, so that its RCU callbacks are invoked by a per-CPU kthread whose name begins diff --git a/init/main.c b/init/main.c index bb1aed928f21..e3c4cdd94d5b 100644 --- a/init/main.c +++ b/init/main.c @@ -578,6 +578,7 @@ asmlinkage __visible void __init start_kernel(void) idr_init_cache(); rcu_init(); tick_nohz_init(); + rcu_init_nohz(); context_tracking_init(); radix_tree_init(); /* init some links before init_ISA_irqs() */ |