On Tue, Nov 21, 2023 at 08:58:40AM +0800, Chengming Zhou wrote: > On 2023/11/21 02:49, Mark Brown wrote: > > On Thu, Nov 02, 2023 at 03:23:27AM +0000, chengming.zhou@xxxxxxxxx wrote: > > When we see problems we see RCU stalls while logging in, for example: > > [ 46.453323] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: > > [ 46.459361] rcu: 3-...0: (1 GPs behind) idle=def4/1/0x40000000 softirq=1304/1304 fqs=951 > > [ 46.467669] rcu: (detected by 0, t=2103 jiffies, g=1161, q=499 ncpus=4) > > [ 46.474472] Sending NMI from CPU 0 to CPUs 3: > IIUC, here should print the backtrace of CPU 3, right? It looks like CPU 3 is the cause, > but we couldn't see what it's doing from the log. AIUI yes, but it looks like we've just completely lost the CPU - there's more attempts to talk to it visible in the log: > > A full log for that run can be seen at: > > > > https://validation.linaro.org/scheduler/job/4017095 but none of them appear to cause CPU 3 to respond. Note that 32 bit ARM is just using a regular IPI rather than something that's actually a NMI so this isn't hugely out of the ordinary, I'd guess it's stuck with interrupts masked.
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