linux-kernel - Re: [PATCH -v4 RESEND 6/9] mm, THP, swap: Support to add/delete THP to/from swap cache

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Date:   Fri, 28 Oct 2016 16:30:43 +0800
From:   "Huang\, Ying" <ying.huang@...el.com>
To:     Hillf Danton <hillf.zj@...baba-inc.com>
Cc:     "'Huang\, Ying'" <ying.huang@...el.com>,
        'Andrew Morton' <akpm@...ux-foundation.org>,
        <tim.c.chen@...el.com>, <dave.hansen@...el.com>,
        <andi.kleen@...el.com>, <aaron.lu@...el.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, 'Hugh Dickins' <hughd@...gle.com>,
        'Shaohua Li' <shli@...nel.org>,
        "'Minchan Kim'" <minchan@...nel.org>,
        'Rik van Riel' <riel@...hat.com>,
        "'Andrea Arcangeli'" <aarcange@...hat.com>,
        "'Kirill A . Shutemov'" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH -v4 RESEND 6/9] mm, THP, swap: Support to add/delete THP to/from swap cache

Hi, Hillf,

Hillf Danton <hillf.zj@...baba-inc.com> writes:

> On Friday, October 28, 2016 1:56 PM Huang, Ying wrote:
>> 
>> @@ -109,9 +118,16 @@ int __add_to_swap_cache(struct page *page, swp_entry_t entry)
>>  		 * So add_to_swap_cache() doesn't returns -EEXIST.
>>  		 */
>>  		VM_BUG_ON(error == -EEXIST);
>> -		set_page_private(page, 0UL);
>>  		ClearPageSwapCache(page);
>> -		put_page(page);
>> +		set_page_private(cur_page, 0UL);
>> +		while (i--) {
>> +			cur_page--;
>> +			cur_entry.val--;
>> +			set_page_private(cur_page, 0UL);
>> +			radix_tree_delete(&address_space->page_tree,
>> +					  swp_offset(cur_entry));
>> +		}
>
> Pull pages out of radix tree with tree lock held?

OOPS, I should hold the tree lock for the error path too.  Will update
it in the next version.  Thanks for pointing out this!

Best Regards,
Huang, Ying


>> +		page_ref_sub(page, nr);
>>  	}
>> 
>>  	return error;
>>