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Date:   Wed, 5 Apr 2023 14:50:36 +0200
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Subject: Re: kernel 6.2 stuck at boot (efi_call_rts) on arm64
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From:   "Linux regression tracking #update (Thorsten Leemhuis)" 
        <regressions@leemhuis.info>
To:     Andrea Righi <andrea.righi@canonical.com>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Paolo Pisati <paolo.pisati@canonical.com>,
        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Linux kernel regressions list <regressions@lists.linux.dev>
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          Linux regressions mailing list 
          <regressions@lists.linux.dev>
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[TLDR: This mail in primarily relevant for Linux kernel regression
tracking. See link in footer if these mails annoy you.]

On 16.03.23 10:45, Linux regression tracking #adding (Thorsten Leemhuis)
wrote:
> On 16.03.23 08:54, Andrea Righi wrote:
>> Hello,
>>
>> the latest v6.2.6 kernel fails to boot on some arm64 systems, the kernel
>> gets stuck and never completes the boot. On the console I see this:
>>
>> [   72.043484] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
>> [   72.049571] rcu:     22-...0: (30 GPs behind) idle=b10c/1/0x4000000000000000 softirq=164/164 fqs=6443
>> [   72.058520]     (detected by 28, t=15005 jiffies, g=449, q=174 ncpus=32)
>> [   72.064949] Task dump for CPU 22:
>> [   72.068251] task:kworker/u64:5   state:R  running task     stack:0     pid:447   ppid:2      flags:0x0000000a
>> [   72.078156] Workqueue: efi_rts_wq efi_call_rts
>> [   72.082595] Call trace:
>> [   72.085029]  __switch_to+0xbc/0x100
>> [   72.088508]  0xffff80000fe83d4c
>>
>> After that, as a consequence, I start to get a lot of hung task timeout traces.
>>
>> I tried to bisect the problem and I found that the offending commit is
>> this one:
>>
>>  e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized")
>>
>> I've reverted this commit for now and everything works just fine, but I
>> was wondering if the problem could be caused by a lack of entropy on
>> these arm64 boxes or something else.
> 
> Thanks for the report. To be sure the issue doesn't fall through the
> cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
> tracking bot:
> 
> #regzbot ^introduced e7b813b32a42
> #regzbot title efi: stuck at boot (efi_call_rts) on arm64
> #regzbot ignore-activity

#regzbot fix: eb684408f3ea4856
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
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