Messages in this thread Patch in this message | | | Date | Tue, 09 Oct 2018 13:56:14 -0700 | From | Sodagudi Prasad <> | Subject | livelock with hrtimer cpu_base->lock |
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Hi Will,
This is regarding - thread "try to fix contention between expire_timers and try_to_del_timer_sync". https://lkml.org/lkml/2017/7/28/172
I think this live lockup issue was discussed earlier but the final set of changes were not concluded. I would like to check whether you have new updates on this issue or not. This problem is observed with 4.14 .64 stable kernel too. We see this problem 2 times in overnight testing.
I have to add the following code to avoid live lock. I am thinking that fixing this at the cpu_relax() level.
+++ b/kernel/time/hrtimer.c @@ -52,6 +52,7 @@ #include <linux/timer.h> #include <linux/freezer.h> #include <linux/compat.h> +#include <linux/delay.h>
#include <linux/uaccess.h>
@@ -152,6 +153,7 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags); } cpu_relax(); + udelay(1); } }
@@ -1067,6 +1069,7 @@ int hrtimer_cancel(struct hrtimer *timer) if (ret >= 0) return ret; cpu_relax(); + udelay(1); } } EXPORT_SYMBOL_GPL(hrtimer_cancel); Note:- Timer event streaming is enabled and still live lock observed.
-Thanks, Prasad
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