sparc64: Fix tick/stick comparator equal-compare hazard

[PATCH 0/1] sparc64: Fix tick/stick comparator equal-compare hazard

Tony Rodriguez posted 1 patch 6 days, 3 hours ago

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arch/sparc/kernel/time_64.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

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[PATCH 0/1] sparc64: Fix tick/stick comparator equal-compare hazard

Posted by Tony Rodriguez 6 days, 3 hours ago

sparc64: avoid missed timer interrupts when comparator equals counter

This patch fixes an equal‑compare hazard in the SPARC64 tick/stick comparator
logic that can cause missed timer interrupts and stalled hrtimers.

Full dmesg and crash dumps:
https://github.com/unixpro1970/Sparc64-Kernel-Debugging-Dumps/blob/main/s7-2-05122026-dump.tar.gz

Debugging discussion:
https://lore.kernel.org/all/87tssb6olo.ffs@tglx/
https://lore.kernel.org/all/871pfcznw0.ffs@tglx/

Short dmesg excerpt:
[   48.632215] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[   48.676018] rcu: rcu_sched kthread timer wakeup didn't happen for 5259 jiffies!
[   48.743621] rcu:     Possible timer handling issue on cpu=100 timer-softirq=15

Test summary:
After applying this patch, S7-2 and T7-1 systems no longer hang on v7 and v7.1 kernels.

Tony Rodriguez (1):
  sparc64: Fix tick/stick comparator equal-compare hazard

 arch/sparc/kernel/time_64.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

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2.53.0