diff options
| author | Chen Yu <yu.c.chen@intel.com> | 2020-06-23 14:31:31 +0800 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2020-06-23 17:06:55 +0200 |
| commit | 81e6737518a1e392ead4e568a4ee70bb7c371458 (patch) | |
| tree | 09bbe2ade20b5aba68cf11f342a1b1e3623fde91 | |
| parent | 48778464bb7d346b47157d21ffde2af6b2d39110 (diff) | |
PM: s2idle: Clear _TIF_POLLING_NRFLAG before suspend to idle
Suspend to idle was found to not work on Goldmont CPU recently.
The issue happens due to:
1. On Goldmont the CPU in idle can only be woken up via IPIs,
not POLLING mode, due to commit 08e237fa56a1 ("x86/cpu: Add
workaround for MONITOR instruction erratum on Goldmont based
CPUs")
2. When the CPU is entering suspend to idle process, the
_TIF_POLLING_NRFLAG remains on, because cpuidle_enter_s2idle()
doesn't match call_cpuidle() exactly.
3. Commit b2a02fc43a1f ("smp: Optimize send_call_function_single_ipi()")
makes use of _TIF_POLLING_NRFLAG to avoid sending IPIs to idle
CPUs.
4. As a result, some IPIs related functions might not work
well during suspend to idle on Goldmont. For example, one
suspected victim:
tick_unfreeze() -> timekeeping_resume() -> hrtimers_resume()
-> clock_was_set() -> on_each_cpu() might wait forever,
because the IPIs will not be sent to the CPUs which are
sleeping with _TIF_POLLING_NRFLAG set, and Goldmont CPU
could not be woken up by only setting _TIF_NEED_RESCHED
on the monitor address.
To avoid that, clear the _TIF_POLLING_NRFLAG flag before invoking
enter_s2idle_proper() in cpuidle_enter_s2idle() in analogy with the
call_cpuidle() code flow.
Fixes: b2a02fc43a1f ("smp: Optimize send_call_function_single_ipi()")
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: Rafael J. Wysocki <rafael@kernel.org>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
[ rjw: Subject / changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index c149d9e20dfd..e092789187c6 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -13,6 +13,7 @@ #include <linux/mutex.h> #include <linux/sched.h> #include <linux/sched/clock.h> +#include <linux/sched/idle.h> #include <linux/notifier.h> #include <linux/pm_qos.h> #include <linux/cpu.h> @@ -186,7 +187,7 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) * be frozen safely. */ index = find_deepest_state(drv, dev, U64_MAX, 0, true); - if (index > 0) + if (index > 0 && !current_clr_polling_and_test()) enter_s2idle_proper(drv, dev, index); return index; |