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

[David Hildenbrand <david@redhat.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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