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authorChen Yu <yu.c.chen@intel.com>2020-06-23 14:31:31 +0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-06-23 17:06:55 +0200
commit81e6737518a1e392ead4e568a4ee70bb7c371458 (patch)
tree09bbe2ade20b5aba68cf11f342a1b1e3623fde91
parent48778464bb7d346b47157d21ffde2af6b2d39110 (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.c3
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;