Re: [RFC PATCH 2/5] mm, arch: unify vmemmap_populate altmap handling

From: Michal Hocko <mhocko@kernel.org>
To: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Jerome Glisse <jglisse@redhat.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	qiuxishi@huawei.com, Kani Toshimitsu <toshi.kani@hpe.com>,
	slaoub@gmail.com, Joonsoo Kim <js1304@gmail.com>,
	Andi Kleen <ak@linux.intel.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Paul Mackerras <paulus@samba.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tony Luck <tony.luck@intel.com>,
	Will Deacon <will.deacon@arm.com>
Subject: Re: [RFC PATCH 2/5] mm, arch: unify vmemmap_populate altmap handling
Date: Mon, 31 Jul 2017 14:55:56 +0200	[thread overview]
Message-ID: <20170731125555.GB4829@dhcp22.suse.cz> (raw)
In-Reply-To: <20170731144053.38c8b012@thinkpad>

On Mon 31-07-17 14:40:53, Gerald Schaefer wrote:
[...]
> > @@ -247,12 +248,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> >  			 * use large frames even if they are only partially
> >  			 * used.
> >  			 * Otherwise we would have also page tables since
> > -			 * vmemmap_populate gets called for each section
> > +			 * __vmemmap_populate gets called for each section
> >  			 * separately. */
> >  			if (MACHINE_HAS_EDAT1) {
> >  				void *new_page;
> > 
> > -				new_page = vmemmap_alloc_block(PMD_SIZE, node);
> > +				new_page = __vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> >  				if (!new_page)
> >  					goto out;
> >  				pmd_val(*pm_dir) = __pa(new_page) | sgt_prot;
> 
> There is another call to vmemmap_alloc_block() in this function, a couple
> of lines below, this should also be replaced by __vmemmap_alloc_block_buf().

I've noticed that one but in general I have only transformed PMD
mappings because we shouldn't even get to pte level if the forme works
AFAICS. Memory sections should be always 2MB aligned unless I am missing
something. Or is this not true?
-- 
Michal Hocko
SUSE Labs

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