linux-kernel - Re: [PATCH v2 4/5] mm/hwpoison: Fix incorrect "not recovered" report for recovered clean pages

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Message-ID: <7cb06f0b-dd90-506e-64f6-d3bbcae8c95f@huawei.com>
Date: Thu, 20 Feb 2025 09:16:44 +0800
From: Miaohe Lin <linmiaohe@...wei.com>
To: "Luck, Tony" <tony.luck@...el.com>, Shuai Xue <xueshuai@...ux.alibaba.com>
CC: "tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com"
	<mingo@...hat.com>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>,
	"hpa@...or.com" <hpa@...or.com>, "akpm@...ux-foundation.org"
	<akpm@...ux-foundation.org>, "peterz@...radead.org" <peterz@...radead.org>,
	"jpoimboe@...nel.org" <jpoimboe@...nel.org>, "linux-edac@...r.kernel.org"
	<linux-edac@...r.kernel.org>, "linux-kernel@...r.kernel.org"
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	"bp@...en8.de" <bp@...en8.de>, "nao.horiguchi@...il.com"
	<nao.horiguchi@...il.com>
Subject: Re: [PATCH v2 4/5] mm/hwpoison: Fix incorrect "not recovered" report
 for recovered clean pages

On 2025/2/20 1:15, Luck, Tony wrote:
>>> The caller kill_me_maybe will do set_mce_nospec + sync_core again.
>>>
>>> static void kill_me_maybe(struct callback_head *cb)
>>> {
>>>     struct task_struct *p = container_of(cb, struct task_struct, mce_kill_me);
>>>     int flags = MF_ACTION_REQUIRED;
>>>     ...
>>>     ret = memory_failure(pfn, flags);
>>>     if (!ret) {
>>>             set_mce_nospec(pfn);
>>>             sync_core();
>>>             return;
>>>     }
>>>
>>> Is this expected?
>>>
>>
>> the second set_mce_nospec do nothing and have no side affect.
>>
>> sync_core() is introduced by Tony [1]:
>>
>> Also moved sync_core(). The comments for this function say that it should
>> only be called when instructions have been changed/re-mapped. Recovery for
>> an instruction fetch may change the physical address. But that doesn't happen
>> until the scheduled work runs (which could be on another CPU).
>>
>> [1]https://lore.kernel.org/all/20200824221237.5397-1-tony.luck@intel.com/T/#u
>>
>> IMHO, I think it also has no side affect.
>>
>> @Tony, could you help to confirm this?
> 
> Correct. Re-runing these calls is harmless.

Got it. Thanks both.

> 
> -Tony
>