linux-kernel - Re: [QUESTION] problems report: rcu_read_unlock_special() called in irq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c16ddb6e-73f1-4eff-bbcf-c03b95f79fdf@nvidia.com>
Date: Wed, 2 Jul 2025 13:24:00 -0400
From: Joel Fernandes <joelagnelf@...dia.com>
To: Qi Xi <xiqi2@...wei.com>, paulmck@...nel.org,
 Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc: Joel Fernandes <joel@...lfernandes.org>, ankur.a.arora@...cle.com,
 Frederic Weisbecker <frederic@...nel.org>, Boqun Feng
 <boqun.feng@...il.com>, neeraj.upadhyay@...nel.org, urezki@...il.com,
 rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
 "Wangshaobo (bobo)" <bobo.shaobowang@...wei.com>,
 Xie XiuQi <xiexiuqi@...wei.com>
Subject: Re: [QUESTION] problems report: rcu_read_unlock_special() called in
 irq_exit() causes dead loop



On 7/2/2025 6:59 AM, Joel Fernandes wrote:
> 
> 
> On 7/2/2025 5:14 AM, Qi Xi wrote:
>> Hi Joel,
>>
>> After applying the 2 patches, the problem still exists. Compared to the previous
>> fixes which did solve the problem, the difference is ct_in_irq() in the first
>> patch.
>>
>> I am wondering why "nesting != CT_NESTING_IRQ_NONIDLE" is added?
>>
>>
>> (previous fix: problem is solved)
>>
>> +bool ct_in_irq(void)
>> +{
>> +    return ct_nmi_nesting() != 0;
>> +}
>>
>> (current fix: problem still exists)
>>
>> +bool ct_in_irq(void)
>> +{
>> +    long nesting = ct_nmi_nesting();
>> +
>> +    return (nesting && nesting != CT_NESTING_IRQ_NONIDLE);
>> +}
> 
> Oh gosh, thanks for spotting that! Indeed,  I had changed it to != 0 in the last
> version but applied an older patch. I will fix it in the tree. Thank you again!
> 
> Neeraj, would you like this as a separate commit that you can then squash? Or
> could you fix it up in your tree?
> 
Qi, Xiongfeng, I am currently working on alternative fix after discussing with
the crew. I will keep you posted with the fix, and would it to be good to get
your testing on it once I have it (hopefully in couple of days), thanks for the
report!

 - Joel