| Message ID | 20210104152058.36642-1-frederic@kernel.org |
|---|---|
| Headers | show |
| Series | sched/idle: Fix missing need_resched() checks after rcu_idle_enter() v2 | expand |
Hi Frederic, On Mon, Jan 4, 2021 at 12:21 PM Frederic Weisbecker <frederic@kernel.org> wrote: > > Entering RCU idle mode may cause a deferred wake up of an RCU NOCB_GP > kthread (rcuog) to be serviced. > > Usually a wake up happening while running the idle task is spotted in > one of the need_resched() checks carefully placed within the idle loop > that can break to the scheduler. > > Unfortunately imx6q_enter_wait() is beyond the last generic > need_resched() check and it performs a wfi right away after the call to > rcu_idle_enter(). We may halt the CPU with a resched request unhandled, > leaving the task hanging. > > Fix this with performing a last minute need_resched() check after > calling rcu_idle_enter(). Shouldn't tif_need_resched() be used instead of need_resched() in the commit log?
The only code change in this v2 is the use of tif_need_resched() instead of need_resched() on 3/4 (build issue reported on linux-next). The rest is added Tested-by and Reviewed-by tags. git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git sched/idle-v2 HEAD: c246718af0112c8624ec9c46a85bf0ef1562e050 Thanks, Frederic --- Frederic Weisbecker (4): sched/idle: Fix missing need_resched() check after rcu_idle_enter() cpuidle: Fix missing need_resched() check after rcu_idle_enter() ARM: imx6q: Fix missing need_resched() check after rcu_idle_enter() ACPI: processor: Fix missing need_resched() check after rcu_idle_enter() arch/arm/mach-imx/cpuidle-imx6q.c | 8 +++++++- drivers/acpi/processor_idle.c | 10 ++++++++-- drivers/cpuidle/cpuidle.c | 33 +++++++++++++++++++++++++-------- kernel/sched/idle.c | 18 ++++++++++++------ 4 files changed, 52 insertions(+), 17 deletions(-)