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Date: Mon, 18 Dec 2023 07:54:20 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Shuai Xue <xueshuai@linux.alibaba.com>
Cc: bp@alien8.de, rafael@kernel.org, wangkefeng.wang@huawei.com,
	tanxiaofei@huawei.com, mawupeng1@huawei.com, tony.luck@intel.com,
	linmiaohe@huawei.com, naoya.horiguchi@nec.com, james.morse@arm.com,
	will@kernel.org, jarkko@kernel.org, linux-acpi@vger.kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org, linux-edac@vger.kernel.org,
	acpica-devel@lists.linuxfoundation.org, stable@vger.kernel.org,
	x86@kernel.org, justin.he@arm.com, ardb@kernel.org,
	ying.huang@intel.com, ashish.kalra@amd.com,
	baolin.wang@linux.alibaba.com, tglx@linutronix.de, mingo@redhat.com,
	dave.hansen@linux.intel.com, lenb@kernel.org, hpa@zytor.com,
	robert.moore@intel.com, lvying6@huawei.com, xiexiuqi@huawei.com,
	zhuo.song@linux.alibaba.com
Subject: Re: [PATCH v10 4/4] ACPI: APEI: handle synchronous exceptions in
 task work
Message-ID: <2023121813-monthly-matriarch-2df4@gregkh>
References: <20221027042445.60108-1-xueshuai@linux.alibaba.com>
 <20231218064521.37324-5-xueshuai@linux.alibaba.com>
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In-Reply-To: <20231218064521.37324-5-xueshuai@linux.alibaba.com>

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>