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Subject: Re: [REF PATCH] mm/swap: fix swapon failure
From:   Alex Shi <alex.shi@linux.alibaba.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     linmiaohe@huawei.com, akpm@linux-foundation.org,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Hugh Dickins <hughd@google.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <1604922436-16597-1-git-send-email-alex.shi@linux.alibaba.com>
 <20201109120705.GZ17076@casper.infradead.org>
 <88fb2ed0-cb0c-2b4b-a73e-3a64fdc0a2cd@linux.alibaba.com>
Message-ID: <46e34498-01aa-3442-eee3-d3b84a00e1a8@linux.alibaba.com>
Date:   Mon, 9 Nov 2020 20:36:08 +0800
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?? 2020/11/9 ????8:17, Alex Shi д??:
> 
> 
> ?? 2020/11/9 ????8:07, Matthew Wilcox д??:
>> On Mon, Nov 09, 2020 at 07:47:16PM +0800, Alex Shi wrote:
>>> Go through the context I found the exit_swap_address_space(p->type)
>>> shouldn't be used in good result path. So just move it to error path.
>>
>> But ... it's not used in the success path.  There's a 'goto' right
>> before it.  Does this really fix your problem?
>>
> 
> The trick thing is. It do fix my problem on my centos 7 with gcc 8.3.1...
> 
> I am getting headache on this problem...

Checked again on my git tree. nothing weird, and code based on
cf7cd542d1b5 Add linux-next specific files for 20201104

Sorry, I have no idea where is the problem...


> 
>>> @@ -3339,7 +3339,8 @@ static bool swap_discardable(struct swap_info_struct *si)
>>>  	error = inode_drain_writes(inode);
>>>  	if (error) {
>>>  		inode->i_flags &= ~S_SWAPFILE;
>>> -		goto free_swap_address_space;
>>> +		exit_swap_address_space(p->type);
>>> +		goto bad_swap_unlock_inode;
>>>  	}
>>>  
>>>  	mutex_lock(&swapon_mutex);
>>> @@ -3364,8 +3365,6 @@ static bool swap_discardable(struct swap_info_struct *si)
>>>  
>>>  	error = 0;
>>>  	goto out;
>>> -free_swap_address_space:
>>> -	exit_swap_address_space(p->type);
>>>  bad_swap_unlock_inode:
>>>  	inode_unlock(inode);
>>>  bad_swap:
>>> -- 
>>> 1.8.3.1
>>>
>>>