linux-kernel - Re: [PATCH 4/5] mm/vma: Replace all remaining open encodings with vma_set

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Date:   Mon, 17 Feb 2020 17:26:14 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Sudeep Dutt <sudeep.dutt@...el.com>,
        Ashutosh Dixit <ashutosh.dixit@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Allison Randal <allison@...utok.net>,
        Richard Fontana <rfontana@...hat.com>
Subject: Re: [PATCH 4/5] mm/vma: Replace all remaining open encodings with
 vma_set_anonymous()



On 02/17/2020 03:57 PM, Kirill A. Shutemov wrote:
> On Mon, Feb 17, 2020 at 10:33:52AM +0530, Anshuman Khandual wrote:
>> This replaces all remaining open encodings with vma_set_anonymous().
>>
>> Cc: Sudeep Dutt <sudeep.dutt@...el.com>
>> Cc: Ashutosh Dixit <ashutosh.dixit@...el.com>
>> Cc: Arnd Bergmann <arnd@...db.de>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Kate Stewart <kstewart@...uxfoundation.org>
>> Cc: Allison Randal <allison@...utok.net>
>> Cc: Richard Fontana <rfontana@...hat.com>
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
>> ---
>>  drivers/misc/mic/scif/scif_mmap.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/misc/mic/scif/scif_mmap.c b/drivers/misc/mic/scif/scif_mmap.c
>> index a151d416f39c..1f0dec5df994 100644
>> --- a/drivers/misc/mic/scif/scif_mmap.c
>> +++ b/drivers/misc/mic/scif/scif_mmap.c
>> @@ -580,7 +580,7 @@ static void scif_munmap(struct vm_area_struct *vma)
>>  	 * The kernel probably zeroes these out but we still want
>>  	 * to clean up our own mess just in case.
>>  	 */
>> -	vma->vm_ops = NULL;
>> +	vma_set_anonymous(vma);
>>  	vma->vm_private_data = NULL;
>>  	kref_put(&vmapvt->ref, vma_pvt_release);
>>  	scif_delete_vma(ep, vma);
> 
> This is misleading. The VMA doesn't become anonymous here. This is undo of
> the previously overwritten vm_ops. I think we should leave it opencodded.

I was bit unsure about it as well, thanks for the clarification. Will drop it.