linux-kernel - Re: [PATCH v16 1/3] ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered

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Message-ID: <64dff7c7-95c9-48e5-b549-ec37ed6a6587@linux.alibaba.com>
Date: Wed, 6 Nov 2024 14:07:14 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: Yazen Ghannam <yazen.ghannam@....com>
Cc: mark.rutland@....com, catalin.marinas@....com, mingo@...hat.com,
 robin.murphy@....com, Jonathan.Cameron@...wei.com, bp@...en8.de,
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 naoya.horiguchi@....com, james.morse@....com, tongtiangen@...wei.com,
 gregkh@...uxfoundation.org, will@...nel.org, jarkko@...nel.org,
 linux-acpi@...r.kernel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
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 robert.moore@...el.com, lvying6@...wei.com, xiexiuqi@...wei.com,
 zhuo.song@...ux.alibaba.com
Subject: Re: [PATCH v16 1/3] ACPI: APEI: send SIGBUS to current task if
 synchronous memory error not recovered



在 2024/11/5 23:09, Yazen Ghannam 写道:
> On Mon, Nov 04, 2024 at 09:54:28AM +0800, Shuai Xue wrote:
>> Synchronous error was detected as a result of user-space process accessing
>> a 2-bit uncorrected error. The CPU will take a synchronous error exception
>> such as Synchronous External Abort (SEA) on Arm64. The kernel will queue a
>> memory_failure() work which poisons the related page, unmaps the page, and
>> then sends a SIGBUS to the process, so that a system wide panic can be
>> avoided.
>>
>> However, no memory_failure() work will be queued when abnormal synchronous
>> errors occur. These errors can include situations such as invalid PA,
>> unexpected severity, no memory failure config support, invalid GUID
>> section, etc. In such case, the user-space process will trigger SEA again.
>> This loop can potentially exceed the platform firmware threshold or even
>> trigger a kernel hard lockup, leading to a system reboot.
>>
>> Fix it by performing a force kill if no memory_failure() work is queued
>> for synchronous errors.
>>
>> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com>
>> Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>> ---
>>   drivers/acpi/apei/ghes.c | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
>> index ada93cfde9ba..af3339dd3817 100644
>> --- a/drivers/acpi/apei/ghes.c
>> +++ b/drivers/acpi/apei/ghes.c
>> @@ -801,6 +801,16 @@ static bool ghes_do_proc(struct ghes *ghes,
>>   		}
>>   	}
>>   
>> +	/*
>> +	 * If no memory failure work is queued for abnormal synchronous
>> +	 * errors, do a force kill.
>> +	 */
>> +	if (sync && !queued) {
>> +		pr_err(HW_ERR GHES_PFX "%s:%d: hardware memory corruption (SIGBUS)\n",
> 
> Is this always a memory error? The code flow above implies that an
> unrecoverable ARM processor error can all be !queued. So should the
> message be more generic like "synchronous unrecoverable error" or
> similar?

Yes, you are right. Will fix it.
> 
> In any case, this is just a minor nit if this is not an issue in
> practice.
> 
> Reviewed-by: Yazen Ghannam <yazen.ghannam@....com>
> 
> Thanks,
> Yazen

Thank you for valuable comments.
Shuai