Re: [PATCH v10 2/4] ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Dec 18, 2023 at 02:45:19PM +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>
> ---
>  drivers/acpi/apei/ghes.c | 9 +++++++++
>  1 file changed, 9 insertions(+)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>