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Message-ID: <1427216312.2515.46.camel@j-VirtualBox>
Subject: Re: [PATCH] mm: Remove usages of ACCESS_ONCE
From: Jason Low <jason.low2@hp.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
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Date: Tue, 24 Mar 2015 09:58:32 -0700
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On Tue, 2015-03-24 at 15:42 +0100, Christian Borntraeger wrote:
> Am 23.03.2015 um 23:44 schrieb Jason Low:
> > Commit 38c5ce936a08 converted ACCESS_ONCE usage in gup_pmd_range() to
> > READ_ONCE, since ACCESS_ONCE doesn't work reliably on non-scalar types.
> > 
> > This patch removes the rest of the usages of ACCESS_ONCE, and use
> > READ_ONCE for the read accesses. This also makes things cleaner,
> > instead of using separate/multiple sets of APIs.
> > 
> > Signed-off-by: Jason Low <jason.low2@hp.com>
> 
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>

Thanks.

> one remark or question:
> 
> > -	anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
> > +	anon_mapping = (unsigned long)READ_ONCE(page->mapping);
> 
> Were the white space changes intentional? IIRC checkpatch does prefer
> it your way and you have changed several places - so I assume yes.

Yeah, those changes were intentional.

I thought that this was more of the standard style to do casting, so I
made those changes as well.

> Either way, its probably fine to change that along.

Okay, I'll assume that this is fine for now unless something thinks this
shouldn't be part of the patch.