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Date: Sat, 3 Feb 2024 15:56:04 +0800
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Subject: Re: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to
 MCE_IN_KERNEL_COPY_MC
To: "Luck, Tony" <tony.luck@intel.com>, Borislav Petkov <bp@alien8.de>
CC: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
	"wangkefeng.wang@huawei.com" <wangkefeng.wang@huawei.com>, Dave Hansen
	<dave.hansen@linux.intel.com>, "x86@kernel.org" <x86@kernel.org>, "H. Peter
 Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Peter Zijlstra
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	Guohanjun <guohanjun@huawei.com>
References: <20240111135548.3207437-1-tongtiangen@huawei.com>
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From: Tong Tiangen <tongtiangen@huawei.com>
In-Reply-To: <SJ1PR11MB6083FDC9D4661A9D94E26ABDFC422@SJ1PR11MB6083.namprd11.prod.outlook.com>
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在 2024/2/3 6:46, Luck, Tony 写道:
>> Now, since you're explaining things today :) pls explain to me what this
>> patchset is all about? You having reviewed patch 3 and all?
>>
>> Why is this pattern:
>>
>>        if (copy_mc_user_highpage(dst, src, addr, vma)) {
>>                memory_failure_queue(page_to_pfn(src), 0);
>>
>> not good anymore?
>>
>> Or is the goal here to poison straight from the #MC handler and not
>> waste time and potentially get another #MC while memory_failure_queue()
>> on the source address is done?
>>
>> Or something completely different?
> 
> See the comment above memory_failure_queue()
> 
> * The function is primarily of use for corruptions that
>   * happen outside the current execution context (e.g. when
>   * detected by a background scrubber)
> 
> In the copy_mc_user_highpage() case the fault happens in
> the current execution context. So scheduling someone else
> to handle it at some future point is risky. Just deal with it
> right away.
> 
> -Tony

The goal of this patch:
   When #MC is triggered by copy_mc_user_highpage(), #MC is directly
processed in the synchronously triggered do_machine_check() ->
kill_me_never() -> memory_failure().

And the current handling is to call memory_failure_queue() ->
schedule_work_on() in the execution context, I think that's what
"scheduling someone else to handle it at some future point is risky."

Thanks.
Tong.