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Subject: Re: [PATCH v9 06/24] mm: make pte_unmap_same compatible with SPF
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From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date: Wed, 28 Mar 2018 12:43:15 +0200
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To: David Rientjes <rientjes@google.com>
Cc: paulmck@linux.vnet.ibm.com, peterz@infradead.org, Andrew Morton <akpm@linux-foundation.org>, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox <willy@infradead.org>, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, hpa@zytor.com, Will Deacon <will.deacon@arm.com>, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, Andrea Arcangeli <aarcange@redhat.com>, Alexei Starovoitov <alexei.starovoitov@gmail.com>, kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com, Daniel Jordan <daniel.m.jordan@oracle.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen <tim.c.chen@linux.intel.com>, linuxppc-dev@lists.ozlabs.org, x86@kernel.org



On 28/03/2018 12:20, David Rientjes wrote:
> On Wed, 28 Mar 2018, Laurent Dufour wrote:
> 
>>>> @@ -2913,7 +2921,8 @@ int do_swap_page(struct vm_fault *vmf)
>>>>  	int exclusive = 0;
>>>>  	int ret = 0;
>>>
>>> Initialization is now unneeded.
>>
>> I'm sorry, what "initialization" are you talking about here ?
>>
> 
> The initialization of the ret variable.
> 
> @@ -2913,7 +2921,8 @@ int do_swap_page(struct vm_fault *vmf)
>  	int exclusive = 0;
>  	int ret = 0;
> 
> -	if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
> +	ret = pte_unmap_same(vmf);
> +	if (ret)
>  		goto out;
> 
>  	entry = pte_to_swp_entry(vmf->orig_pte);
> 
> "ret" is immediately set to the return value of pte_unmap_same(), so there 
> is no need to initialize it to 0.

Sorry, I missed that. I'll remove this initialization.

Thanks,
Laurent.