linux-kernel - Re: [PATCH 0/8] memblock: introduce memsize showing reserved memory

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Date:   Fri, 25 Mar 2022 10:46:30 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Jaewon Kim <jaewon31.kim@...sung.com>
Cc:     vbabka@...e.cz, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, ytk.lee@...sung.com,
        jaewon31.kim@...il.com
Subject: Re: [PATCH 0/8] memblock: introduce memsize showing reserved memory

Hi,

On Thu, Mar 24, 2022 at 04:01:50PM +0900, Jaewon Kim wrote:
> Some of memory regions can be reserved for a specific purpose. They are
> usually defined through reserved-memory in device tree. If only size
> without address is specified in device tree, the address of the region
> will be determined at boot time.
> 
> We may find the address of the memory regions through booting log, but
> it does not show all. And it could be hard to catch the very beginning
> log. The memblock_dump_all shows all memblock status but it does not
> show region name and its information is difficult to summarize.
> 
> This patch introduce a debugfs node, memblock/memsize, to see reserved
> memory easily.
> 
> Here's an example
> 
> $ cat debugfs/memblock/memsize
> 0x0f9000000-0x0fb000000 0x02000000 (   32768 KB )   map reusable linux,cma
> 0x0b1900000-0x0b1b00000 0x00200000 (    2048 KB ) nomap unusable test1
> 0x0b0200000-0x0b0400000 0x00200000 (    2048 KB )   map unusable test2
>  (snipped)
> 
> Reserved    :  746924 KB
>  .kernel    :  137027 KB
>   .text     :   28158 KB
>   .rwdata   :    3238 KB
>   .rodata   :   13468 KB
>   .bss      :   12570 KB
>   .etc      :   79593 KB
>  .unusable  :  609897 KB
> System      : 3447380 KB
>  .common    : 3152468 KB
>  .reusable  :  294912 KB
> Total       : 4194304 KB (  4096.00 MB )

Most of this information information is already available at various
places, like the existing memblock debugfs, /proc/iomem and DT sysfs.

I don't see why we need yet another debugfs file to expose it.
 
> Jaewon Kim (8):
>   memblock: introduce memsize showing reserved memory
>   memblock: detect hidden memory hole size
>   memblock: handle overlapped reserved memory region
>   memblock: track memblock changed at early param
>   memblock: track kernel size on memsize
>   memblock: recognize late free by checking PageReserved
>   memblock: print memsize summary information
>   memblock: print kernel internal size
> 
>  drivers/of/fdt.c             |  10 +
>  drivers/of/of_reserved_mem.c |   7 +-
>  include/linux/memblock.h     |  21 ++
>  include/linux/mm.h           |   3 +
>  init/main.c                  |  13 +-
>  kernel/dma/contiguous.c      |   9 +-
>  mm/Kconfig                   |   7 +
>  mm/memblock.c                | 434 ++++++++++++++++++++++++++++++++++-
>  mm/page_alloc.c              |  15 +-
>  9 files changed, 506 insertions(+), 13 deletions(-)
> 
> -- 
> 2.17.1
> 

-- 
Sincerely yours,
Mike.