Received-SPF: pass (google.com: domain of linux-ext4+bounces-2032-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Thu, 11 Apr 2024 09:37:33 -0400
From: Peter Xu <peterx@redhat.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>, linux-mm@kvack.org,
	david@fromorbit.com, dan.j.williams@intel.com, jhubbard@nvidia.com,
	rcampbell@nvidia.com, willy@infradead.org,
	linux-fsdevel@vger.kernel.org, jack@suse.cz, djwong@kernel.org,
	hch@lst.de, david@redhat.com, ruansy.fnst@fujitsu.com,
	nvdimm@lists.linux.dev, linux-xfs@vger.kernel.org,
	linux-ext4@vger.kernel.org, jglisse@redhat.com
Subject: Re: [RFC 02/10] mm/hmm: Remove dead check for HugeTLB and FS DAX
Message-ID: <ZhfnnYfqWKZn5Inh@x1n>
References: <cover.fe275e9819458a4bbb9451b888cafb88af8867d4.1712796818.git-series.apopple@nvidia.com>
 <e4a877d1f77d778a2e820b9df66f6b7422bf2276.1712796818.git-series.apopple@nvidia.com>
 <20240411122530.GQ5383@nvidia.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20240411122530.GQ5383@nvidia.com>

On Thu, Apr 11, 2024 at 09:25:30AM -0300, Jason Gunthorpe wrote:
> On Thu, Apr 11, 2024 at 10:57:23AM +1000, Alistair Popple wrote:
> > pud_huge() returns true only for a HugeTLB page. pud_devmap() is only
> > used by FS DAX pages. These two things are mutually exclusive so this
> > code is dead code and can be removed.
> 
> I'm not sure this is true.. pud_huge() is mostly a misspelling of pud_leaf()..
> 
> > -	if (pud_huge(pud) && pud_devmap(pud)) {
> 
> I suspect this should be written as:
> 
>    if (pud_leaf(pud) && pud_devmap(pud)) {
> 
> In line with Peter's work here:
> 
> https://lore.kernel.org/linux-mm/20240321220802.679544-1-peterx@redhat.com/

Just to provide more information for Alistair, this patch already switched
that over to a _leaf():

https://lore.kernel.org/r/20240318200404.448346-12-peterx@redhat.com

That's in mm-unstable now, so should see that in a rebase.

And btw it's great to see that pxx_devmap() can go away.

Thanks,

-- 
Peter Xu