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

[PINTU KUMAR]

----- Original Message -----
> From: Michal Nazarewicz <mina86@xxxxxxxxxx>
> To: Pintu Kumar <pintu.k@xxxxxxxxxxx>; akpm@xxxxxxxxxxxxxxxxxxxx; riel@xxxxxxxxxx; pintu.k@xxxxxxxxxxx; aquini@xxxxxxxxxx; paul.gortmaker@xxxxxxxxxxxxx; jmarchan@xxxxxxxxxx; lcapitulino@xxxxxxxxxx; kirill.shutemov@xxxxxxxxxxxxxxx; m.szyprowski@xxxxxxxxxxx; aneesh.kumar@xxxxxxxxxxxxxxxxxx; iamjoonsoo.kim@xxxxxxx; lauraa@xxxxxxxxxxxxxx; gioh.kim@xxxxxxx; mgorman@xxxxxxx; rientjes@xxxxxxxxxx; hannes@xxxxxxxxxxx; vbabka@xxxxxxx; sasha.levin@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx
> Cc: pintu_agarwal@xxxxxxxxx; cpgs@xxxxxxxxxxx; vishnu.ps@xxxxxxxxxxx; rohit.kr@xxxxxxxxxxx; ed.savinay@xxxxxxxxxxx
> Sent: Thursday, 23 October 2014 10:31 PM
> 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@xxxxxxxxxxx>
>> Signed-off-by: Vishnu Pratap Singh <vishnu.ps@xxxxxxxxxxx>
> 
> Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
> 
> 
> 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.
> 

In our earlier patch (first version), we added it in cmc.c itself.
But, Andrew wanted this variable to be visible in non-CMA case as well to avoid build error, when we use 
this variable in mem_init_print_info, without CONFIG_CMA.
So, we moved it to page_alloc.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,  MichaÅ âmina86â Nazarewicz    (o o)
> ooo +--<mpn@xxxxxxxxxx>--<xmpp:mina86@xxxxxxxxxx>--ooO--(_)--Ooo--
> 
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