linux-kernel - Re: [PATCH 3/4] mm/memory: convert do_shared

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Date:   Mon, 3 Jul 2023 19:18:57 -0700
From:   Sidhartha Kumar <sidhartha.kumar@...cle.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org
Subject: Re: [PATCH 3/4] mm/memory: convert do_shared_fault() to folios

On 7/3/23 4:31 PM, Matthew Wilcox wrote:
> On Sun, Jul 02, 2023 at 10:58:49PM -0700, Sidhartha Kumar wrote:
>> Saves three implicit calls to compound_head().
>>
>> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
>> ---
>>   mm/memory.c | 9 +++++----
>>   1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 93480e846ace6..33bf13431974c 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -4594,6 +4594,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
>>   {
>>   	struct vm_area_struct *vma = vmf->vma;
>>   	vm_fault_t ret, tmp;
>> +	struct folio *folio = page_folio(vmf->page);
> 
> You can't call page_folio() until after __do_fault().  Did you test this
> series?

I thought it would be straightforward enough without testing but I 
didn't realize the initialization in __do_fault(). I will test and 
incorporate the other suggestions for a v2.

Thanks
> 
>>   	ret = __do_fault(vmf);
>>   	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))