linux-kernel - Re: [PATCH v2 1/2] mm: cma: split cma-reserved in dmesg log

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Date:	Thu, 23 Oct 2014 19:01:02 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Pintu Kumar <pintu.k@...sung.com>, akpm@...ux-foundation.org,
	riel@...hat.com, pintu.k@...sung.com, aquini@...hat.com,
	paul.gortmaker@...driver.com, jmarchan@...hat.com,
	lcapitulino@...hat.com, kirill.shutemov@...ux.intel.com,
	m.szyprowski@...sung.com, aneesh.kumar@...ux.vnet.ibm.com,
	iamjoonsoo.kim@....com, lauraa@...eaurora.org, gioh.kim@....com,
	mgorman@...e.de, rientjes@...gle.com, hannes@...xchg.org,
	vbabka@...e.cz, sasha.levin@...cle.com,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:	pintu_agarwal@...oo.com, cpgs@...sung.com, vishnu.ps@...sung.com,
	rohit.kr@...sung.com, ed.savinay@...sung.com
Subject: Re: [PATCH v2 1/2] mm: cma: split cma-reserved in dmesg log

On Wed, Oct 22 2014, Pintu Kumar wrote:
> When the system boots up, in the dmesg logs we can see
> the memory statistics along with total reserved as below.
> Memory: 458840k/458840k available, 65448k reserved, 0K highmem
>
> When CMA is enabled, still the total reserved memory remains the same.
> However, the CMA memory is not considered as reserved.
> But, when we see /proc/meminfo, the CMA memory is part of free memory.
> This creates confusion.
> This patch corrects the problem by properly subtracting the CMA reserved
> memory from the total reserved memory in dmesg logs.
>
> Below is the dmesg snapshot from an arm based device with 512MB RAM and
> 12MB single CMA region.
>
> Before this change:
> Memory: 458840k/458840k available, 65448k reserved, 0K highmem
>
> After this change:
> Memory: 458840k/458840k available, 53160k reserved, 12288k cma-reserved, 0K highmem
>
> Signed-off-by: Pintu Kumar <pintu.k@...sung.com>
> Signed-off-by: Vishnu Pratap Singh <vishnu.ps@...sung.com>

Acked-by: Michal Nazarewicz <mina86@...a86.com>


I'm not sure how Andrew would think about it, and I don't have strong
feelings, but I would consider a few changes:

> ---
> v2: Moved totalcma_pages extern declaration to linux/cma.h
>     Removed CONFIG_CMA while show cma-reserved, from page_alloc.c
>     Moved totalcma_pages declaration to page_alloc.c, so that if will be visible 
>     in non-CMA cases.
>  include/linux/cma.h |    1 +
>  mm/cma.c            |    1 +
>  mm/page_alloc.c     |    6 ++++--
>  3 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/cma.h b/include/linux/cma.h
> index 0430ed0..0b75896 100644
> --- a/include/linux/cma.h
> +++ b/include/linux/cma.h
> @@ -15,6 +15,7 @@
>  
>  struct cma;
>  
> +extern unsigned long totalcma_pages;

+#ifdef CONFIG_CMA
+extern unsigned long totalcma_pages;
+#else
+#  define totalcma_pages 0UL
+#endif

>  extern phys_addr_t cma_get_base(struct cma *cma);
>  extern unsigned long cma_get_size(struct cma *cma);
>  
> diff --git a/mm/cma.c b/mm/cma.c
> index 963bc4a..8435762 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -288,6 +288,7 @@ int __init cma_declare_contiguous(phys_addr_t base,
>  	if (ret)
>  		goto err;
>  
> +	totalcma_pages += (size / PAGE_SIZE);
>  	pr_info("Reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
>  		(unsigned long)base);
>  	return 0;
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index dd73f9a..ababbd8 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -110,6 +110,7 @@ static DEFINE_SPINLOCK(managed_page_count_lock);
>  
>  unsigned long totalram_pages __read_mostly;
>  unsigned long totalreserve_pages __read_mostly;
> +unsigned long totalcma_pages __read_mostly;

Move this to cma.c.

>  /*
>   * When calculating the number of globally allowed dirty pages, there
>   * is a certain number of per-zone reserves that should not be
> @@ -5520,7 +5521,7 @@ void __init mem_init_print_info(const char *str)
>  
>  	pr_info("Memory: %luK/%luK available "
>  	       "(%luK kernel code, %luK rwdata, %luK rodata, "
> -	       "%luK init, %luK bss, %luK reserved"
> +	       "%luK init, %luK bss, %luK reserved, %luK cma-reserved"
>  #ifdef	CONFIG_HIGHMEM
>  	       ", %luK highmem"
>  #endif
> @@ -5528,7 +5529,8 @@ void __init mem_init_print_info(const char *str)
>  	       nr_free_pages() << (PAGE_SHIFT-10), physpages << (PAGE_SHIFT-10),
>  	       codesize >> 10, datasize >> 10, rosize >> 10,
>  	       (init_data_size + init_code_size) >> 10, bss_size >> 10,
> -	       (physpages - totalram_pages) << (PAGE_SHIFT-10),
> +	       (physpages - totalram_pages - totalcma_pages) << (PAGE_SHIFT-10),
> +	       totalcma_pages << (PAGE_SHIFT-10),
>  #ifdef	CONFIG_HIGHMEM
>  	       totalhigh_pages << (PAGE_SHIFT-10),
>  #endif
> -- 
> 1.7.9.5
>

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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