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Date:   Sat, 2 Mar 2019 13:51:44 -0500
From:   Andrea Arcangeli <aarcange@redhat.com>
To:     Jan Stancek <jstancek@redhat.com>
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org,
        peterz@infradead.org, riel@surriel.com, mhocko@suse.com,
        ying.huang@intel.com, jrdr.linux@gmail.com, jglisse@redhat.com,
        aneesh.kumar@linux.ibm.com, david@redhat.com, raquini@redhat.com,
        rientjes@google.com, kirill@shutemov.name,
        mgorman@techsingularity.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm/memory.c: do_fault: avoid usage of stale
 vm_area_struct
Message-ID: <20190302185144.GD31083@redhat.com>
References: <20190302171043.GP11592@bombadil.infradead.org>
 <a5234d11b8cc158352a2f97fc33aa9ad90bb287b.1551550112.git.jstancek@redhat.com>
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Hello Jan,

On Sat, Mar 02, 2019 at 07:19:39PM +0100, Jan Stancek wrote:
> +	struct mm_struct *vm_mm = READ_ONCE(vma->vm_mm);

The vma->vm_mm cannot change under gcc there, so no need of
READ_ONCE. The release of mmap_sem has release semantics so the
vma->vm_mm access cannot be reordered after up_read(mmap_sem) either.

Other than the above detail:

Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>

Thanks,
Andrea