Re: [PATCH V6 1/2] mm/page_alloc: Make alloc_gigantic_page() available for general use

From: David Hildenbrand <david@redhat•com>
To: Anshuman Khandual <anshuman.khandual@arm•com>, linux-mm@kvack•org
Cc: Mark Rutland <mark.rutland@arm•com>,
	linux-ia64@vger•kernel.org, linux-sh@vger•kernel.org,
	Peter Zijlstra <peterz@infradead•org>,
	James Hogan <jhogan@kernel•org>,
	Heiko Carstens <heiko.carstens@de•ibm.com>,
	Michal Hocko <mhocko@kernel•org>,
	Dave Hansen <dave.hansen@intel•com>,
	Paul Mackerras <paulus@samba•org>,
	sparclinux@vger•kernel.org, Thomas Gleixner <tglx@linutronix•de>,
	Andrea Arcangeli <aarcange@redhat•com>,
	linux-s390@vger•kernel.org, Jason Gunthorpe <jgg@ziepe•ca>,
	Michael Ellerman <mpe@ellerman•id.au>,
	x86@kernel•org, Russell King - ARM Linux <linux@armlinux•org.uk>,
	Matthew Wilcox <willy@infradead•org>,
	Steven Price <Steven.Price@arm•com>,
	Tetsuo Handa <penguin-kernel@i-love•sakura.ne.jp>,
	Gerald Schaefer <gerald.schaefer@de•ibm.com>,
	David Rientjes <rientjes@google•com>,
	linux-snps-arc@lists•infradead.org,
	linux-arm-kernel@lists•infradead.org,
	Kees Cook <keescook@chromium•org>,
	Masahiro Yamada <yamada.masahiro@socionext•com>,
	linuxppc-dev@lists•ozlabs.org, Mark Brown <broonie@kernel•org>,
	"Kirill A . Shutemov" <kirill@shutemov•name>,
	Dan Williams <dan.j.williams@intel•com>,
	Vlastimil Babka <vbabka@suse•cz>,
	Oscar Salvador <osalvador@suse•de>,
	Christophe Leroy <christophe.leroy@c-s•fr>,
	Sri Krishna chowdary <schowdary@nvidia•com>,
	Ard Biesheuvel <ard.biesheuvel@linaro•org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
	linux-mips@vger•kernel.org, Ralf Baechle <ralf@linux-mips•org>,
	linux-kernel@vger•kernel.org, Paul Burton <paul.burton@mips•com>,
	Mike Rapoport <rppt@linux•vnet.ibm.com>,
	Vineet Gupta <vgupta@synopsys•com>,
	Martin Schwidefsky <schwidefsky@de•ibm.com>,
	Andrew Morton <akpm@linux-foundation•org>,
	Mel Gorman <mgorman@techsingularity•net>,
	"David S. Miller" <davem@davemloft•net>,
	Mike Kravetz <mike.kravetz@oracle•com>
Subject: Re: [PATCH V6 1/2] mm/page_alloc: Make alloc_gigantic_page() available for general use
Date: Tue, 15 Oct 2019 13:42:03 +0200	[thread overview]
Message-ID: <9da1f196-51bd-06ac-c5dc-b55776fce2be@redhat.com> (raw)
In-Reply-To: <1571131302-32290-2-git-send-email-anshuman.khandual@arm.com>

On 15.10.19 11:21, Anshuman Khandual wrote:
> alloc_gigantic_page() implements an allocation method where it scans over
> various zones looking for a large contiguous memory block which could not
> have been allocated through the buddy allocator. A subsequent patch which
> tests arch page table helpers needs such a method to allocate PUD_SIZE
> sized memory block. In the future such methods might have other use cases
> as well. So alloc_gigantic_page() has been split carving out actual memory
> allocation method and made available via new alloc_gigantic_page_order()
> which is wrapped under CONFIG_CONTIG_ALLOC.
> 
> Cc: Andrew Morton <akpm@linux-foundation•org>
> Cc: Vlastimil Babka <vbabka@suse•cz>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
> Cc: Thomas Gleixner <tglx@linutronix•de>
> Cc: Mike Rapoport <rppt@linux•vnet.ibm.com>
> Cc: Mike Kravetz <mike.kravetz@oracle•com>
> Cc: Jason Gunthorpe <jgg@ziepe•ca>
> Cc: Dan Williams <dan.j.williams@intel•com>
> Cc: Peter Zijlstra <peterz@infradead•org>
> Cc: Michal Hocko <mhocko@kernel•org>
> Cc: Mark Rutland <mark.rutland@arm•com>
> Cc: Mark Brown <broonie@kernel•org>
> Cc: Steven Price <Steven.Price@arm•com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro•org>
> Cc: Masahiro Yamada <yamada.masahiro@socionext•com>
> Cc: Kees Cook <keescook@chromium•org>
> Cc: Tetsuo Handa <penguin-kernel@i-love•sakura.ne.jp>
> Cc: Matthew Wilcox <willy@infradead•org>
> Cc: Sri Krishna chowdary <schowdary@nvidia•com>
> Cc: Dave Hansen <dave.hansen@intel•com>
> Cc: Russell King - ARM Linux <linux@armlinux•org.uk>
> Cc: Michael Ellerman <mpe@ellerman•id.au>
> Cc: Paul Mackerras <paulus@samba•org>
> Cc: Martin Schwidefsky <schwidefsky@de•ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de•ibm.com>
> Cc: "David S. Miller" <davem@davemloft•net>
> Cc: Vineet Gupta <vgupta@synopsys•com>
> Cc: James Hogan <jhogan@kernel•org>
> Cc: Paul Burton <paul.burton@mips•com>
> Cc: Ralf Baechle <ralf@linux-mips•org>
> Cc: Kirill A. Shutemov <kirill@shutemov•name>
> Cc: Gerald Schaefer <gerald.schaefer@de•ibm.com>
> Cc: Christophe Leroy <christophe.leroy@c-s•fr>
> Cc: David Rientjes <rientjes@google•com>
> Cc: Andrea Arcangeli <aarcange@redhat•com>
> Cc: Oscar Salvador <osalvador@suse•de>
> Cc: Mel Gorman <mgorman@techsingularity•net>
> Cc: linux-snps-arc@lists•infradead.org
> Cc: linux-mips@vger•kernel.org
> Cc: linux-arm-kernel@lists•infradead.org
> Cc: linux-ia64@vger•kernel.org
> Cc: linuxppc-dev@lists•ozlabs.org
> Cc: linux-s390@vger•kernel.org
> Cc: linux-sh@vger•kernel.org
> Cc: sparclinux@vger•kernel.org
> Cc: x86@kernel•org
> Cc: linux-kernel@vger•kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm•com>
> ---
>   include/linux/gfp.h |  3 ++
>   mm/hugetlb.c        | 76 +----------------------------------
>   mm/page_alloc.c     | 98 +++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 102 insertions(+), 75 deletions(-)
> 
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index fb07b503dc45..379ad23437d1 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -589,6 +589,9 @@ static inline bool pm_suspended_storage(void)
>   /* The below functions must be run on a range from a single zone. */
>   extern int alloc_contig_range(unsigned long start, unsigned long end,
>   			      unsigned migratetype, gfp_t gfp_mask);
> +extern struct page *alloc_gigantic_page_order(unsigned int order,
> +					      gfp_t gfp_mask, int nid,
> +					      nodemask_t *nodemask);
>   #endif
>   void free_contig_range(unsigned long pfn, unsigned int nr_pages);
>   
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 977f9a323a7a..d199556a4a2c 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1023,86 +1023,12 @@ static void free_gigantic_page(struct page *page, unsigned int order)
>   }
>   
>   #ifdef CONFIG_CONTIG_ALLOC
> -static int __alloc_gigantic_page(unsigned long start_pfn,
> -				unsigned long nr_pages, gfp_t gfp_mask)
> -{
> -	unsigned long end_pfn = start_pfn + nr_pages;
> -	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
> -				  gfp_mask);
> -}
> -
> -static bool pfn_range_valid_gigantic(struct zone *z,
> -			unsigned long start_pfn, unsigned long nr_pages)
> -{
> -	unsigned long i, end_pfn = start_pfn + nr_pages;
> -	struct page *page;
> -
> -	for (i = start_pfn; i < end_pfn; i++) {
> -		if (!pfn_valid(i))
> -			return false;
> -
> -		page = pfn_to_page(i);

Am I missing something or should here really be a pfn_to_online_page() 
here instead of a pfn_valid() ?

-- 

Thanks,

David / dhildenb

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