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

Shuai Xue
2024-11-06T06:07:21Z

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@linux.alibaba.com>
>> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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@amd.com>
>
> Thanks,
> Yazen

Thank you for valuable comments.
Shuai