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Subject: Re: [PATCH 5/6] mm, hwpoison: kill procs if unmap fails
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        <naoya.horiguchi@nec.com>
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        "linux-mm@kvack.org" <linux-mm@kvack.org>,
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References: <20220818130016.45313-1-linmiaohe@huawei.com>
 <20220818130016.45313-6-linmiaohe@huawei.com>
 <20220819052431.GE613144@hori.linux.bs1.fc.nec.co.jp>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <3043d61b-468b-58a3-b6b8-081f4663fbac@huawei.com>
Date:   Fri, 19 Aug 2022 15:37:23 +0800
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On 2022/8/19 13:24, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Thu, Aug 18, 2022 at 09:00:15PM +0800, Miaohe Lin wrote:
>> If try_to_unmap() fails, the hwpoisoned page still resides in the address
>> space of some processes. We should kill these processes or the hwpoisoned
>> page might be consumed later. collect_procs() is always called to collect
>> relevant processes now so they can be killed later if unmap fails.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>>  mm/memory-failure.c | 9 ++++-----
>>  1 file changed, 4 insertions(+), 5 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index a2f4e8b00a26..5f9615a86296 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1396,7 +1396,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
>>  	struct address_space *mapping;
>>  	LIST_HEAD(tokill);
>>  	bool unmap_success;
>> -	int kill = 1, forcekill;
>> +	int forcekill;
>>  	bool mlocked = PageMlocked(hpage);
>>  
>>  	/*
>> @@ -1437,7 +1437,6 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
>>  		if (page_mkclean(hpage)) {
>>  			SetPageDirty(hpage);
>>  		} else {
>> -			kill = 0;
>>  			ttu |= TTU_IGNORE_HWPOISON;
>>  			pr_info("%#lx: corrupted page was clean: dropped without side effects\n",
>>  				pfn);
>> @@ -1452,8 +1451,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
>>  	 * Error handling: We ignore errors here because
>>  	 * there's nothing that can be done.
> 
> This above comment might be deprecated now (I'm not sure what this really mean),
> so could you drop or update this?

Do you mean remove the below comment? In fact, this doesn't make much sense for me.

* Error handling: We ignore errors here because
* there's nothing that can be done.

> 
> Anyway, the patch looks good to me.
> 
> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Many thanks for review.

Thanks,
Miaohe Lin