From: Qian Cai <cai@lca.pw>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: rcu@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: Boot warning at rcu_check_gp_start_stall()
Date: Tue, 21 Jan 2020 14:09:05 -0500 [thread overview]
Message-ID: <6A6B0325-64C4-4470-91B4-37104CF8DA1A@lca.pw> (raw)
In-Reply-To: <20200121161533.GT2935@paulmck-ThinkPad-P72>
> On Jan 21, 2020, at 11:15 AM, Paul E. McKenney <paulmck@kernel.org> wrote:
>
> On Tue, Jan 21, 2020 at 09:37:13AM -0500, Qian Cai wrote:
>>
>>
>>> On Jan 21, 2020, at 9:19 AM, Paul E. McKenney <paulmck@kernel.org> wrote:
>>>
>>> One approach would be to boot with rcupdate.rcu_cpu_stall_timeout=300,
>>> which would allow more time.
>>
>> It works for me if once that warning triggered, give a bit information about adjusting the parameter when debugging options are on to suppress the warning due to expected long boot.
>
> Indeed. 300 seconds as shown above is currently the maximum, but
> please let me know if it needs to be increased. This module parameter
> is writable after boot via sysfs, so maybe that could be part of the
> workaround.
>
>>> Longer term, I could suppress this warning during boot when
>>> CONFIG_EFI_PGT_DUMP=y, but that sounds quite specific. Alternatively,
>>> I could provide a Kconfig option that suppressed this during boot
>>> that was selected by whatever long-running boot-time Kconfig option
>>> needed it. Yet another approach would be for long-running operations
>>> like efi_dump_pagetable() to suppress stalls on entry and re-enable them
>>> upon exit.
>>>
>>> Thoughts?
>>
>> None of the options sounds particularly better for me because there could come up with other options may trigger this, memtest comes in mind, for example. Then, it is a bit of pain to maintain of unknown.
>
> I was afraid of that. ;-)
>
> Could you please send me the full dmesg up to that point? No promises,
> but it might well be that I can make some broad-spectrum adjustment
> within RCU. Only one way to find out…
https://cailca.github.io/files/dmesg.txt
next prev parent reply other threads:[~2020-01-21 19:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 4:25 Boot warning at rcu_check_gp_start_stall() Qian Cai
2020-01-21 5:09 ` Paul E. McKenney
2020-01-21 11:45 ` Qian Cai
2020-01-21 14:19 ` Paul E. McKenney
2020-01-21 14:37 ` Qian Cai
2020-01-21 16:15 ` Paul E. McKenney
2020-01-21 19:09 ` Qian Cai [this message]
2020-01-21 20:46 ` Paul E. McKenney
2020-01-22 4:16 ` Qian Cai
2020-01-22 5:07 ` Paul E. McKenney
2020-01-22 5:20 ` Qian Cai
2020-01-22 16:50 ` Paul E. McKenney
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