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Subject: Re: [PATCH 2/3] hugetlb: take hugetlb vma_lock when clearing
 vma_lock->vma pointer
To:     Mike Kravetz <mike.kravetz@oracle.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
CC:     Muchun Song <songmuchun@bytedance.com>,
        David Hildenbrand <david@redhat.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Michal Hocko <mhocko@suse.com>, Peter Xu <peterx@redhat.com>,
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        Ray Fucillo <Ray.Fucillo@intersystems.com>,
        Andrew Morton <akpm@linux-foundation.org>
References: <20221005011707.514612-1-mike.kravetz@oracle.com>
 <20221005011707.514612-3-mike.kravetz@oracle.com> <Yz5L1uxQYR1VqFtJ@monkey>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <6b2d8b41-1989-b28a-d558-3423432848fe@huawei.com>
Date:   Sat, 15 Oct 2022 09:32:45 +0800
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On 2022/10/6 11:30, Mike Kravetz wrote:
> To address build issues:
> 
> 
>>>From b6d359f77d32c7734fe4f00806a0ed1e99925534 Mon Sep 17 00:00:00 2001
> From: Mike Kravetz <mike.kravetz@oracle.com>
> Date: Wed, 5 Oct 2022 20:26:19 -0700
> Subject: [PATCH 2/3] hugetlb: take hugetlb vma_lock when clearing
>  vma_lock->vma pointer
> 
> hugetlb file truncation/hole punch code may need to back out and take
> locks in order in the routine hugetlb_unmap_file_folio().  This code
> could race with vma freeing as pointed out in [1] and result in
> accessing a stale vma pointer.  To address this, take the vma_lock when
> clearing the vma_lock->vma pointer.
> 
> [1] https://lore.kernel.org/linux-mm/01f10195-7088-4462-6def-909549c75ef4@huawei.com/
> 
> Fixes: "hugetlb: use new vma_lock for pmd sharing synchronization"
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>

This patch looks good to me. Thanks.

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks,
Miaohe Lin