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Message-ID: <5dbe2246-fb9d-4bc8-82a2-8cbffa913b6e@amd.com>
Date: Thu, 24 Apr 2025 10:00:36 +0530
From: "Aithal, Srikanth" <sraithal@....com>
To: paulmck@...nel.org, Bert Karwatzki <spasswolf@....de>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Kuniyuki Iwashima <kuniyu@...zon.com>, Mateusz Guzik <mjguzik@...il.com>,
Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>,
John Ogness <john.ogness@...utronix.de>,
Sergey Senozhatsky <senozhatsky@...omium.org>, linux-kernel@...r.kernel.org,
Linux-Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: commit dd4cf8c9e1f4 leads to failed boot
On 4/24/2025 1:26 AM, Paul E. McKenney wrote:
> On Wed, Apr 23, 2025 at 09:19:56PM +0200, Bert Karwatzki wrote:
>> Am Mittwoch, dem 23.04.2025 um 11:07 -0700 schrieb Paul E. McKenney:
>>> On Wed, Apr 23, 2025 at 08:49:08PM +0530, Aithal, Srikanth wrote:
>>>> On 4/23/2025 7:48 PM, Paul E. McKenney wrote:
>>>>> On Wed, Apr 23, 2025 at 07:09:42PM +0530, Aithal, Srikanth wrote:
>>>>>> On 4/23/2025 5:24 PM, Bert Karwatzki wrote:
>>>>>>> Since linux next-20250422 booting fails on my MSI Alpha 15 Laptop runnning
>>>>>>> debian sid. When booting kernel message appear on screen but no messages from
>>>>>>> init (systemd). There are also no logs written even thought emergency sync
>>>>>>> via magic sysrq works (a message is printed on screen), presumably because
>>>>>>> / is not mounted. I bisected this (from 6.15-rc3 to next-20250422) and found
>>>>>>> commit dd4cf8c9e1f4 as the first bad commit.
>>>>>>> Reverting commit dd4cf8c9e1f4 in next-20250422 fixes the issue.
>>>>>>
>>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> On AMD platform as well boot failed starting next-20250422, bisecting the
>>>>>> issue led me to same commit dd4cf8c9e1f4. I have attached kernel config and
>>>>>> logs.
>>>>>
>>>>> Thank you all for the bisection and the report!
>>>>>
>>>>> Please check out the predecessor of commit dd4cf8c9e1f4 ("ratelimit:
>>>>> Force re-initialization when rate-limiting re-enabled"):
>>>>>
>>>>> 13fa70e052dd ("ratelimit: Allow zero ->burst to disable ratelimiting")
>>>>>
>>>>> Then please apply the patch shown below, and let me know what happens?
>>>>> (Yes, I should have split that commit up...)
>>>>>
>>>>> Thanx, Paul
>>>>>
>>>>> ------------------------------------------------------------------------
>>>>>
>>>>> diff --git a/lib/ratelimit.c b/lib/ratelimit.c
>>>>> index 04f16b8e24575..13ed636642270 100644
>>>>> --- a/lib/ratelimit.c
>>>>> +++ b/lib/ratelimit.c
>>>>> @@ -35,7 +35,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
>>>>> unsigned long flags;
>>>>> int ret;
>>>>> - if (!interval || !burst)
>>>>> + if (interval <= 0 || burst <= 0)
>>>>> return 1;
>>>>> /*
>>>>
>>>>
>>>> I applied above patch on top of 13fa70e052dd ("ratelimit: Allow zero ->burst
>>>> to disable ratelimiting") [linux-20250423]. This is fixing the boot issue.
>>>>
>>>> Tested-by: Srikanth Aithal <sraithal@....com>
>>>
>>> Thank you both, and to Bert for intuiting the correct -next commit!
>>>
>>> Could you please try the next increment, which is this patch, again
>>> on top of 24ff89c63355 ("ratelimit: Allow zero ->burst to > disable
>>> ratelimiting")?
>>>
>>> In the meantime, I will expose the version you two just tested to
>>> -next.
>>>
>>> Thanx, Paul
>>>
>>> ------------------------------------------------------------------------
>>>
>>> diff --git a/lib/ratelimit.c b/lib/ratelimit.c
>>> index 04f16b8e24575..8f6c54f719ef2 100644
>>> --- a/lib/ratelimit.c
>>> +++ b/lib/ratelimit.c
>>> @@ -35,8 +35,10 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
>>> unsigned long flags;
>>> int ret;
>>>
>>> - if (!interval || !burst)
>>> + if (interval <= 0 || burst <= 0) {
>>> + ret = burst > 0;
>>> return 1;
>>> + }
>>>
>>> /*
>>> * If we contend on this state's lock then just check if
>>
>> If you set "ret = burst > 0", but "return 1" this will make no difference
>> (except in the case of a major compiler bug, probably), as I wrote in my other
>> email which overlapped yours, this fixes the issue in next-20250422:
>>
>> diff --git a/lib/ratelimit.c b/lib/ratelimit.c
>> index b5c727e976d2..fc28f6cf8269 100644
>> --- a/lib/ratelimit.c
>> +++ b/lib/ratelimit.c
>> @@ -40,7 +40,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
>> * interval says never limit.
>> */
>> if (interval <= 0 || burst <= 0) {
>> - ret = burst > 0;
>> + ret = 1;
>> if (!(READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED) ||
>> !raw_spin_trylock_irqsave(&rs->lock, flags))
>> return ret;
>
> You are quite right, your patch does fix the issue that you three say.
> Unfortunately, it prevents someone from completely suppressing output
> by setting burst to zero. Could you please try the patch below?
>
> Thanx, Paul
I have tested the below patch on top of 13fa70e052dd ("ratelimit: Allow
zero ->burst to disable ratelimiting") [linux-20250423].
This is fixing the boot issue. Thanks again!
Tested-by: Srikanth Aithal <sraithal@....com>
>
> ------------------------------------------------------------------------
>
> diff --git a/lib/ratelimit.c b/lib/ratelimit.c
> index 04f16b8e24575..d6531e5c6ec4e 100644
> --- a/lib/ratelimit.c
> +++ b/lib/ratelimit.c
> @@ -35,8 +35,8 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
> unsigned long flags;
> int ret;
>
> - if (!interval || !burst)
> - return 1;
> + if (interval <= 0 || burst <= 0)
> + return interval == 0 || burst > 0;
>
> /*
> * If we contend on this state's lock then just check if
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