linux-kernel - Re: Suspicious RCU usage in enable_drhd_fault

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Message-ID: <18804ca2-bb8f-46ae-8cce-4c4c3443e027@linux.intel.com>
Date: Fri, 17 Jan 2025 09:20:04 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Breno Leitao <leitao@...ian.org>
Cc: Ido Schimmel <idosch@...sch.org>, iommu@...ts.linux.dev,
 dwmw2@...radead.org, tglx@...utronix.de, peterz@...radead.org,
 linux-kernel@...r.kernel.org
Subject: Re: Suspicious RCU usage in enable_drhd_fault_handling()

On 1/16/25 21:34, Breno Leitao wrote:
> On Tue, Oct 29, 2024 at 09:15:55AM +0800, Baolu Lu wrote:
>> On 2024/10/28 16:43, Ido Schimmel wrote:
>>> Hi,
>>>
>>> I have recently enabled CONFIG_RCU_EXPERT and CONFIG_PROVE_RCU_LIST in
>>> our debug configuration file and started observing the following splat
>>> [1] on one of our machines during boot. Searched the archives, but did
>>> not find a similar report.
>>>
>>> Not sure what is the right fix as I am not familiar with this code, but
>>> I can easily test patches.
>> Thanks for reporting this issue. I've been able to reproduce it locally
>> and will work on a fix. I'll let you know as soon as I have an update.
> Have you had a chance to look at this problem? I am still seeing it in
> 6.13-rc7.

Yes. I have spent some time on this, but I haven't yet figured out a
simple way to fix it.

I tried to add the rcu lock or use the dmar_global_lock instead, but
neither proved successful. Perhaps it's time to reconsider the locking
scheme for those lists.

Thanks,
baolu