@@ -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>
@@ -186,8 +187,10 @@ 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();
enter_s2idle_proper(drv, dev, index);
+ }
return index;
}
Suspend to idle was found to not work on Goldmont CPU recently. And the issue was triggered due to: 1. On Goldmont the CPU in idle can only be woken up via IPIs, not POLL mode: 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 is kept on. 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. I don't find a way in Ubuntu to update the firmware of Goldmont and check if the issue was gone, a fix patch would do no harm. Clear the _TIF_POLLING_NRFLAG flag before entering suspend to idle, and let the driver's enter_s2idle() to decide whether to set _TIF_POLLING_NRFLAG or not. So that to avoid the scenario described above and keep the context consistent with before. Fixes: b2a02fc43a1f ("smp: Optimize send_call_function_single_ipi()") Reported-by: kbuild test robot <lkp@intel.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Chen Yu <yu.c.chen@intel.com> --- drivers/cpuidle/cpuidle.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)