Re: [PATCH v9 05/24] mm: Introduce pte_spinlock for FAULT_FLAG_SPECULATIVE

[Laurent Dufour]

On 25/03/2018 23:50, David Rientjes wrote:
> On Tue, 13 Mar 2018, Laurent Dufour wrote:
> 
>> When handling page fault without holding the mmap_sem the fetch of the
>> pte lock pointer and the locking will have to be done while ensuring
>> that the VMA is not touched in our back.
>>
>> So move the fetch and locking operations in a dedicated function.
>>
>> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
>> ---
>>  mm/memory.c | 15 +++++++++++----
>>  1 file changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 8ac241b9f370..21b1212a0892 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -2288,6 +2288,13 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
>>  }
>>  EXPORT_SYMBOL_GPL(apply_to_page_range);
>>  
>> +static bool pte_spinlock(struct vm_fault *vmf)
> 
> inline?

You're right.
Indeed this was done in the patch 18 : "mm: Provide speculative fault
infrastructure", but this has to be done there too, I'll fix that.

> 
>> +{
>> +	vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
>> +	spin_lock(vmf->ptl);
>> +	return true;
>> +}
>> +
>>  static bool pte_map_lock(struct vm_fault *vmf)
>>  {
>>  	vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
> 
> Shouldn't pte_unmap_same() take struct vm_fault * and use the new 
> pte_spinlock()?

done in the next patch, but you already acked it..