linux-kernel - Re: [PATCH v2] mm/hugetlb: fix DEBUG_LOCKS_WARN_ON(1) when dissolve_free_hugetlb

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Date: Sat, 20 Apr 2024 10:13:06 +0800
From: Miaohe Lin <linmiaohe@...wei.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: <muchun.song@...ux.dev>, <mike.kravetz@...cle.com>, <osalvador@...e.de>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mm/hugetlb: fix DEBUG_LOCKS_WARN_ON(1) when
 dissolve_free_hugetlb_folio()

On 2024/4/20 5:11, Andrew Morton wrote:
> On Fri, 19 Apr 2024 16:58:19 +0800 Miaohe Lin <linmiaohe@...wei.com> wrote:
> 
>> When I did memory failure tests recently, below warning occurs:
>>
>> DEBUG_LOCKS_WARN_ON(1)
>> WARNING: CPU: 8 PID: 1011 at kernel/locking/lockdep.c:232 __lock_acquire+0xccb/0x1ca0
>> Modules linked in: mce_inject hwpoison_inject
>> CPU: 8 PID: 1011 Comm: bash Kdump: loaded Not tainted 6.9.0-rc3-next-20240410-00012-gdb69f219f4be #3
>>
>> ...
>>
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1773,7 +1773,7 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
>>  	 * If vmemmap pages were allocated above, then we need to clear the
>>  	 * hugetlb flag under the hugetlb lock.
>>  	 */
>> -	if (clear_flag) {
>> +	if (folio_test_hugetlb(folio)) {
>>  		spin_lock_irq(&hugetlb_lock);
>>  		__folio_clear_hugetlb(folio);
>>  		spin_unlock_irq(&hugetlb_lock);
> 
> Please let's prepare backportable fixes against current mainline, not
> mm-unstable.  Because fixes against current -rcX and earlier will be
> upstreamed ahead of the mm-unstable and mm-stable material.

Do you mean I need to send one fixup patch against mm-unstable and another
one against current mainline?

> 
> 
> I did this:
> 
> --- a/mm/hugetlb.c~mm-hugetlb-fix-debug_locks_warn_on1-when-dissolve_free_hugetlb_folio
> +++ a/mm/hugetlb.c
> @@ -1781,7 +1781,7 @@ static void __update_and_free_hugetlb_fo
>  	 * If vmemmap pages were allocated above, then we need to clear the
>  	 * hugetlb destructor under the hugetlb lock.
>  	 */
> -	if (clear_dtor) {
> +	if (folio_test_hugetlb(folio)) {

This looks good to me. Thanks for doing this. :)
Thanks.
.

>  		spin_lock_irq(&hugetlb_lock);
>  		__clear_hugetlb_destructor(h, folio);
>  		spin_unlock_irq(&hugetlb_lock);
> _
> 
> .
>