linux-kernel - Re: [PATCH] mm: pgtable: Ensure pml spinlock gets unlock

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Message-ID: <4524511c-d685-4af6-9de9-4f15f7dcfe05@bytedance.com>
Date: Mon, 10 Feb 2025 16:42:13 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: I Hsin Cheng <richard120310@...il.com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: pgtable: Ensure pml spinlock gets unlock



On 2025/2/10 16:31, Qi Zheng wrote:
> 

[...]

>>>>
>>>> diff --git a/mm/pt_reclaim.c b/mm/pt_reclaim.c
>>>> index 7e9455a18aae..163e38f1728d 100644
>>>> --- a/mm/pt_reclaim.c
>>>> +++ b/mm/pt_reclaim.c
>>>> @@ -43,7 +43,7 @@ void try_to_free_pte(struct mm_struct *mm, pmd_t 
>>>> *pmd, unsigned long addr,
>>>>        pml = pmd_lock(mm, pmd);
>>>>        start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, 
>>>> &ptl);
>>>>        if (!start_pte)

Maybe we can return directly here:

             if (!start_pte) {
		spin_unlock(pml);
                 return;
             }

>>>> -        goto out_ptl;
>>>> +        goto out_pte;
>>>>        if (ptl != pml)
>>>>            spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
>>>> @@ -68,4 +68,8 @@ void try_to_free_pte(struct mm_struct *mm, pmd_t 
>>>> *pmd, unsigned long addr,
>>>>            pte_unmap_unlock(start_pte, ptl);
>>>>        if (ptl != pml)
>>>>            spin_unlock(pml);
>>>> +    return;
>>>> +
>>>> +out_pte:
>>>> +    spin_unlock(pml);
>>>>    }
>>