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Subject: Re: [PATCH v2] mm/hugetlb: Don't put_page in lock of hugetlb_lock
To:     Michal Hocko <mhocko@kernel.org>
CC:     <mike.kravetz@oracle.com>, <shenkai8@huawei.com>,
        <linfeilong@huawei.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>, <wangwang2@huawei.com>,
        "Zhoukang (A)" <zhoukang7@huawei.com>,
        Mingfangsen <mingfangsen@huawei.com>, <agl@us.ibm.com>,
        <nacc@us.ibm.com>, Andrew Morton <akpm@linux-foundation.org>
References: <12a693da-19c8-dd2c-ea6a-0a5dc9d2db27@huawei.com>
 <b8ade452-2d6b-0372-32c2-703644032b47@huawei.com>
 <20190506142001.GC31017@dhcp22.suse.cz>
From:   Zhiqiang Liu <liuzhiqiang26@huawei.com>
Message-ID: <d11fa51f-e976-ec33-4f5b-3b26ada64306@huawei.com>
Date:   Mon, 6 May 2019 23:22:08 +0800
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> On Mon 06-05-19 22:06:38, Zhiqiang Liu wrote:
>> From: Kai Shen <shenkai8@huawei.com>
>>
>> spinlock recursion happened when do LTP test:
>> #!/bin/bash
>> ./runltp -p -f hugetlb &
>> ./runltp -p -f hugetlb &
>> ./runltp -p -f hugetlb &
>> ./runltp -p -f hugetlb &
>> ./runltp -p -f hugetlb &
>>
>> The dtor returned by get_compound_page_dtor in __put_compound_page
>> may be the function of free_huge_page which will lock the hugetlb_lock,
>> so don't put_page in lock of hugetlb_lock.
>>
>>  BUG: spinlock recursion on CPU#0, hugemmap05/1079
>>   lock: hugetlb_lock+0x0/0x18, .magic: dead4ead, .owner: hugemmap05/1079, .owner_cpu: 0
>>  Call trace:
>>   dump_backtrace+0x0/0x198
>>   show_stack+0x24/0x30
>>   dump_stack+0xa4/0xcc
>>   spin_dump+0x84/0xa8
>>   do_raw_spin_lock+0xd0/0x108
>>   _raw_spin_lock+0x20/0x30
>>   free_huge_page+0x9c/0x260
>>   __put_compound_page+0x44/0x50
>>   __put_page+0x2c/0x60
>>   alloc_surplus_huge_page.constprop.19+0xf0/0x140
>>   hugetlb_acct_memory+0x104/0x378
>>   hugetlb_reserve_pages+0xe0/0x250
>>   hugetlbfs_file_mmap+0xc0/0x140
>>   mmap_region+0x3e8/0x5b0
>>   do_mmap+0x280/0x460
>>   vm_mmap_pgoff+0xf4/0x128
>>   ksys_mmap_pgoff+0xb4/0x258
>>   __arm64_sys_mmap+0x34/0x48
>>   el0_svc_common+0x78/0x130
>>   el0_svc_handler+0x38/0x78
>>   el0_svc+0x8/0xc
>>
>> Fixes: 9980d744a0 ("mm, hugetlb: get rid of surplus page accounting tricks")
>> Signed-off-by: Kai Shen <shenkai8@huawei.com>
>> Signed-off-by: Feilong Lin <linfeilong@huawei.com>
>> Reported-by: Wang Wang <wangwang2@huawei.com>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> ---
>> v1->v2: add Acked-by: Michal Hocko <mhocko@suse.com>
> 
> A new version for single ack is usually an overkill and only makes the
> situation more confusing. You have also didn't add Cc: stable as
> suggested during the review. That part is arguably more important.
> 
> You also haven't CCed Andrew (now done) and your patch will not get
> merged without him applying it. Anyway, let's wait for Andrew to pick
> this patch up.
> 
Thank you for your patience. I am sorry for misunderstanding your advice
in your last mail.
Does adding Cc: stable mean adding Cc: <stable@vger.kernel.org>
tag in the patch or Ccing stable@vger.kernel.org when sending the new mail?

You are very nice. Thanks again.


>>  mm/hugetlb.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index 6cdc7b2..c1e7b81 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1574,8 +1574,9 @@ static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask,
>>  	 */
>>  	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
>>  		SetPageHugeTemporary(page);
>> +		spin_unlock(&hugetlb_lock);
>>  		put_page(page);
>> -		page = NULL;
>> +		return NULL;
>>  	} else {
>>  		h->surplus_huge_pages++;
>>  		h->surplus_huge_pages_node[page_to_nid(page)]++;
>> -- 
>> 1.8.3.1
>>
>