From: Shuai Xue <xueshuai@linux.alibaba.com>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "Len Brown" <lenb@kernel.org>, "Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Jarkko Sakkinen" <jarkko@kernel.org>,
"HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>,
"linmiaohe@huawei.com" <linmiaohe@huawei.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
Stable <stable@vger.kernel.org>,
"ACPI Devel Maling List" <linux-acpi@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"cuibixuan@linux.alibaba.com" <cuibixuan@linux.alibaba.com>,
"baolin.wang@linux.alibaba.com" <baolin.wang@linux.alibaba.com>,
"zhuo.song@linux.alibaba.com" <zhuo.song@linux.alibaba.com>
Subject: Re: [PATCH v2] ACPI: APEI: do not add task_work to kernel thread to avoid memory leak
Date: Thu, 13 Oct 2022 15:05:49 +0800 [thread overview]
Message-ID: <8313d192-f103-35fc-2931-de0a8eb927ff@linux.alibaba.com> (raw)
In-Reply-To: <79cb9aee-9ad5-00f4-3f7a-9c409f502685@linux.alibaba.com>
Hi, Tony,
在 2022/9/27 AM11:50, Shuai Xue 写道:
>
>
> 在 2022/9/26 PM11:20, Luck, Tony 写道:
>>>>
>>>> - if (task_work_pending && current->mm != &init_mm) {
>>>> + if (task_work_pending && current->mm) {
>>>> estatus_node->task_work.func = ghes_kick_task_work;
>>>> estatus_node->task_work_cpu = smp_processor_id();
>>>> ret = task_work_add(current, &estatus_node->task_work,
>>
>> It seems that you are getting errors reported while running kernel threads. This fix avoids
>> pointlessly adding "task_work" that will never be processed because kernel threads never
>> return to user mode.
>
> Yes, you are right.
>
>>
>> But maybe something else needs to be done? The code was, and with this fix still is,
>> taking no action for the error. That doesn't seem right.
>
> Sorry, I don't think so. As far as I know, on Arm platform, hardware error can signal
> exceptions including:
>
> - Synchronous External Abort (SEA), e,g. data abort or instruction abort
> - Asynchronous External Abort (signalled as SErrors), e,g. L2 can generate SError for
> error responses from the interconnect for a Device or Non-cacheable store
> - Fault Handling and Error Recovery interrupts: DDR mainline/demand/scrubber error interrupt
>
> When the error signals asynchronous exceptions (SError or interrupt), any kind of thread can
> be interrupted, including kernel thread. Because asynchronous exceptions are signaled in
> background, the errors are detected outside of the current execution context.
>
> The GHES driver always queues work to handle memory failure of a page in memory_failure_queue().
> If a kernel thread is interrupted:
>
> - Without this fix, the added task_work will never be processed so that the work will not
> be canceled.
> - With this fix, the task_work will not be added.
>
> In a conclusion, the error will be handled in a kworker with or without this fix.
>
> The point of fix is that:
>
> - The condition is useless because it is always tree. And I think it is not the original patch
> intends to do.
> - The current code leads to memory leaks. The estatus_node will not be freed when task_work is
> added to a kernel thread.
>
>
>>
>> Are you injecting errors to create this scenario?
>
> Yes, I am injecting error to create such scenario. After 200 injections, the ghes_estatus_pool
> will run of memory and ghes_in_nmi_queue_one_entry() returns ENOMEM. Finally, a lot of unhandled
> events may cause platform firmware to exceed some threshold and reboot.
>
>> What does your test do?
>
> My injection includes two steps:
>
> - mmap a device memory for userspace in a driver
> - inject uc and trigger write like ras-tools does
>
> I have opened source the code and you can find here[1]. It's forked from your repo and mainly based
> on your code :)
>
> By the way, do you have any plans to extend ras-tools to Arm platform. And is there a mail-list
> for ras-tools? I send a mail to add test cases to ras-tools several weeks ago, but no response.
> May your mailbox regards it as Spam.
>
Thank you for your review, but I am still having problems with this question.
Do you have any interest to extend ras-tools to Arm platform? I forked a arm-devel branch[1]
from your repo:
- port X86 arch specific cases to Arm platform
- add some common cases like hugetlb, thread and Arm specific cases like prefetch, strb, etc, which
are helpful to test hardware and firmware RAS problems we encountered.
I am pleasure to contribute these code to your upstream repo and looking forward to see a more
powerful and cross platform tools to inject and debug RAS ability on both X86 and Arm platform.
I really appreciate your great work, and look forward to your reply. Thank you.
Best Regards,
Shuai
> [1] https://gitee.com/anolis/ras-tools/tree/arm-devel
next prev parent reply other threads:[~2022-10-13 7:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 5:05 [PATCH] ACPI: APEI: do not add task_work for outside context error Shuai Xue
2022-09-19 2:37 ` Shuai Xue
2022-09-24 7:49 ` [PATCH v2] ACPI: APEI: do not add task_work to kernel thread to avoid memory leak Shuai Xue
2022-09-24 17:17 ` Rafael J. Wysocki
2022-09-26 11:35 ` Shuai Xue
2022-09-26 15:20 ` Luck, Tony
2022-09-27 3:50 ` Shuai Xue
2022-09-27 17:47 ` Luck, Tony
2022-09-29 2:33 ` Shuai Xue
2022-09-29 20:52 ` Luck, Tony
2022-09-30 2:52 ` Shuai Xue
2022-09-30 15:52 ` Luck, Tony
2022-10-04 14:07 ` Rafael J. Wysocki
2022-10-13 7:05 ` Shuai Xue [this message]
2022-10-13 17:18 ` Luck, Tony
2022-10-14 13:23 ` Shuai Xue
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