linux-kernel - Re: [PATCH v9 06/24] mm: make pte_unmap

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Date:   Wed, 28 Mar 2018 12:43:15 +0200
From:   Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To:     David Rientjes <rientjes@...gle.com>
Cc:     paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        kirill@...temov.name, ak@...ux.intel.com, mhocko@...nel.org,
        dave@...olabs.net, jack@...e.cz,
        Matthew Wilcox <willy@...radead.org>, benh@...nel.crashing.org,
        mpe@...erman.id.au, paulus@...ba.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Will Deacon <will.deacon@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        kemi.wang@...el.com, sergey.senozhatsky.work@...il.com,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        haren@...ux.vnet.ibm.com, khandual@...ux.vnet.ibm.com,
        npiggin@...il.com, bsingharora@...il.com,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v9 06/24] mm: make pte_unmap_same compatible with SPF



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.