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From: Ralph Campbell <rcampbell@nvidia.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	nouveau@lists.freedesktop.org,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Christoph Hellwig" <hch@lst.de>
Subject: Re: [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop
Date: Tue, 27 Aug 2019 13:16:13 -0700	[thread overview]
Message-ID: <f5c1f198-4bdd-3c23-428f-764f894b9997@nvidia.com> (raw)
In-Reply-To: <20190827184157.GA24929@ziepe.ca>


On 8/27/19 11:41 AM, Jason Gunthorpe wrote:
> On Fri, Aug 23, 2019 at 03:17:53PM -0700, Ralph Campbell wrote:
> 
>> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
>>   mm/hmm.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/mm/hmm.c b/mm/hmm.c
>> index 29371485fe94..4882b83aeccb 100644
>> +++ b/mm/hmm.c
>> @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
>>   	hmm_vma_walk->last = addr;
>>   	i = (addr - range->start) >> PAGE_SHIFT;
>>   
>> +	if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE))
>> +		return -EPERM;
> 
> Can walk->vma be NULL here? hmm_vma_do_fault() touches it
> unconditionally.
> 
> Jason
> 
walk->vma can be NULL. hmm_vma_do_fault() no longer touches it
unconditionally, that is what the preceding patch fixes.
I suppose I could change hmm_vma_walk_hole_() to check for NULL
and fill in the pfns[] array, I just chose to handle it in
hmm_vma_do_fault().

WARNING: multiple messages have this Message-ID (diff)
From: Ralph Campbell <rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
To: Jason Gunthorpe <jgg-uk2M96/98Pc@public.gmane.org>
Cc: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	"Jérôme Glisse" <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	"Andrew Morton"
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	"Christoph Hellwig" <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop
Date: Tue, 27 Aug 2019 13:16:13 -0700	[thread overview]
Message-ID: <f5c1f198-4bdd-3c23-428f-764f894b9997@nvidia.com> (raw)
In-Reply-To: <20190827184157.GA24929-uk2M96/98Pc@public.gmane.org>


On 8/27/19 11:41 AM, Jason Gunthorpe wrote:
> On Fri, Aug 23, 2019 at 03:17:53PM -0700, Ralph Campbell wrote:
> 
>> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
>>   mm/hmm.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/mm/hmm.c b/mm/hmm.c
>> index 29371485fe94..4882b83aeccb 100644
>> +++ b/mm/hmm.c
>> @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
>>   	hmm_vma_walk->last = addr;
>>   	i = (addr - range->start) >> PAGE_SHIFT;
>>   
>> +	if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE))
>> +		return -EPERM;
> 
> Can walk->vma be NULL here? hmm_vma_do_fault() touches it
> unconditionally.
> 
> Jason
> 
walk->vma can be NULL. hmm_vma_do_fault() no longer touches it
unconditionally, that is what the preceding patch fixes.
I suppose I could change hmm_vma_walk_hole_() to check for NULL
and fill in the pfns[] array, I just chose to handle it in
hmm_vma_do_fault().
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  reply	other threads:[~2019-08-27 20:16 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-23 22:17 [PATCH 0/2] mm/hmm: two bug fixes for hmm_range_fault() Ralph Campbell
2019-08-23 22:17 ` Ralph Campbell
2019-08-23 22:17 ` [PATCH 1/2] mm/hmm: hmm_range_fault() NULL pointer bug Ralph Campbell
2019-08-23 22:17   ` Ralph Campbell
2019-08-24 22:37   ` Christoph Hellwig
2019-08-24 22:37     ` Christoph Hellwig
2019-08-26 18:02     ` Ralph Campbell
2019-08-26 18:02       ` Ralph Campbell
2019-08-26 18:09       ` Jason Gunthorpe
2019-08-26 18:21         ` Ralph Campbell
2019-08-23 22:17 ` [PATCH 2/2] mm/hmm: hmm_range_fault() infinite loop Ralph Campbell
2019-08-23 22:17   ` Ralph Campbell
2019-08-24 22:39   ` Christoph Hellwig
2019-08-27 18:41   ` Jason Gunthorpe
2019-08-27 20:16     ` Ralph Campbell [this message]
2019-08-27 20:16       ` Ralph Campbell
2019-08-27 22:22       ` Jason Gunthorpe
2019-08-27 22:48 ` [PATCH 0/2] mm/hmm: two bug fixes for hmm_range_fault() Jason Gunthorpe

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