linux-kernel - RE: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned

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Message-ID: <3690ece2101d428fb9067fcd2a423ff8@intel.com>
Date:   Mon, 8 Mar 2021 18:54:02 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
CC:     Aili Yao <yaoaili@...gsoft.com>,
        Oscar Salvador <osalvador@...e.de>,
        "david@...hat.com" <david@...hat.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "yangfeng1@...gsoft.com" <yangfeng1@...gsoft.com>
Subject: RE: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned

>> So it should be safe to grab and hold a mutex.  See patch below.
>
> The mutex approach looks simpler and safer, so I'm fine with it.

Thanks.  Is that an "Acked-by:"?

>>  /**
>>   * memory_failure - Handle memory failure of a page.
>>   * @pfn: Page Number of the corrupted page
>> @@ -1424,12 +1426,18 @@ int memory_failure(unsigned long pfn, int flags)
>>  		return -ENXIO;
>>  	}
>>  
>> +	mutex_lock(&mf_mutex);
>
> Is it better to take mutex before memory_failure_dev_pagemap() block?
> Or we don't have to protect against race for device memory?

No races (recovery is only attempted for errors in normal memory).

-Tony