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SubjectRE: [PATCH v2 1/2] mm: cma: split cma-reserved in dmesg log
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----- Original Message -----
> From: Michal Nazarewicz <mina86@mina86.com>
> To: Pintu Kumar <pintu.k@samsung.com>; akpm@linux-foundation.org; riel@redhat.com; pintu.k@samsung.com; aquini@redhat.com; paul.gortmaker@windriver.com; jmarchan@redhat.com; lcapitulino@redhat.com; kirill.shutemov@linux.intel.com; m.szyprowski@samsung.com; aneesh.kumar@linux.vnet.ibm.com; iamjoonsoo.kim@lge.com; lauraa@codeaurora.org; gioh.kim@lge.com; mgorman@suse.de; rientjes@google.com; hannes@cmpxchg.org; vbabka@suse.cz; sasha.levin@oracle.com; linux-kernel@vger.kernel.org; linux-mm@kvack.org
> Cc: pintu_agarwal@yahoo.com; cpgs@samsung.com; vishnu.ps@samsung.com; rohit.kr@samsung.com; ed.savinay@samsung.com
> 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@samsung.com>
>> Signed-off-by: Vishnu Pratap Singh <vishnu.ps@samsung.com>
>
> Acked-by: Michal Nazarewicz <mina86@mina86.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.
>

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, Michał “mina86” Nazarewicz (o o)
> ooo +--<mpn@google.com>--<xmpp:mina86@jabber.org>--ooO--(_)--Ooo--
>
> --
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