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Date: Wed, 28 Mar 2018 03:20:23 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v9 06/24] mm: make pte_unmap_same compatible with SPF
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References: <1520963994-28477-1-git-send-email-ldufour@linux.vnet.ibm.com> <1520963994-28477-7-git-send-email-ldufour@linux.vnet.ibm.com> <alpine.DEB.2.20.1803271417510.31115@chino.kir.corp.google.com>
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To: Laurent Dufour <ldufour@linux.vnet.ibm.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 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.