Re: [PATCH v10 4/4] ACPI: APEI: handle synchronous exceptions in task work

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Dec 18, 2023 at 02:45:21PM +0800, Shuai Xue wrote:
> Hardware errors could be signaled by asynchronous interrupt, e.g. when an
> error is detected by a background scrubber, or signaled by synchronous
> exception, e.g. when a CPU tries to access a poisoned cache line. Both
> synchronous and asynchronous error are queued as a memory_failure() work
> and handled by a dedicated kthread in workqueue.
> 
> However, the memory failure recovery sends SIBUS with wrong BUS_MCEERR_AO
> si_code for synchronous errors in early kill mode, even MF_ACTION_REQUIRED
> is set. The main problem is that the memory failure work is handled in
> kthread context but not the user-space process which is accessing the
> corrupt memory location, so it will send SIGBUS with BUS_MCEERR_AO si_code
> to the user-space process instead of BUS_MCEERR_AR in kill_proc().
> 
> To this end, queue memory_failure() as a task_work so that the current
> context in memory_failure() is exactly belongs to the process consuming
> poison data and it will send SIBBUS with proper si_code.
> 
> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
> Tested-by: Ma Wupeng <mawupeng1@huawei.com>
> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Reviewed-by: Xiaofei Tan <tanxiaofei@huawei.com>
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
>  drivers/acpi/apei/ghes.c | 77 +++++++++++++++++++++++-----------------
>  include/acpi/ghes.h      |  3 --
>  mm/memory-failure.c      | 13 -------
>  3 files changed, 44 insertions(+), 49 deletions(-)
> 


<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>