linux-kernel - Re: [PATCH v2 1/2] mm/userfaultfd: don't place zeropages when zeropages are disallowed

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Message-ID: <b9d9af94-5935-4034-bf3f-9ba283df3ede@redhat.com>
Date: Thu, 11 Apr 2024 14:30:34 +0200
From: David Hildenbrand <david@...hat.com>
To: Alexander Gordeev <agordeev@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Janosch Frank <frankja@...ux.ibm.com>,
 Claudio Imbrenda <imbrenda@...ux.ibm.com>, Heiko Carstens
 <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Peter Xu <peterx@...hat.com>,
 Sven Schnelle <svens@...ux.ibm.com>,
 Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
 Andrea Arcangeli <aarcange@...hat.com>, kvm@...r.kernel.org,
 linux-s390@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mm/userfaultfd: don't place zeropages when
 zeropages are disallowed

On 11.04.24 14:26, Alexander Gordeev wrote:
> On Wed, Mar 27, 2024 at 06:17:36PM +0100, David Hildenbrand wrote:
> 
> Hi David,
> ...
>>   static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
>>   				     struct vm_area_struct *dst_vma,
>>   				     unsigned long dst_addr)
>> @@ -324,6 +355,9 @@ static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
>>   	spinlock_t *ptl;
>>   	int ret;
>>   
>> +	if (mm_forbids_zeropage(dst_vma->mm))
> 
> I assume, you were going to pass dst_vma->vm_mm here?
> This patch does not compile otherwise.

Ah, I compiled it only on x86, where the parameter is ignored ... and 
for testing the code path I forced mm_forbids_zeropage to be 1 on x86.

Yes, this must be dst_vma->vm_mm.

Thanks!

-- 
Cheers,

David / dhildenb