linux-kernel - Re: [PATCH v4] memblock: Add flags and nid info in memblock debugfs

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Message-ID: <20230527103722.GG4967@kernel.org>
Date:   Sat, 27 May 2023 13:37:22 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Yuwei Guan <ssawgyw@...il.com>
Cc:     akpm@...ux-foundation.org, tsahu@...ux.ibm.com,
        anshuman.khandual@....com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] memblock: Add flags and nid info in memblock debugfs

Hi Yuwei,

On Fri, May 19, 2023 at 06:53:21PM +0800, Yuwei Guan wrote:
> Currently, the memblock debugfs can display the count of memblock_type and
> the base and end of the reg. However, when memblock_mark_*() or
> memblock_set_node() is executed on some range, the information in the
> existing debugfs cannot make it clear why the address is not consecutive.
> 
> For example,
> cat /sys/kernel/debug/memblock/memory
>    0: 0x0000000080000000..0x00000000901fffff
>    1: 0x0000000090200000..0x00000000905fffff
>    2: 0x0000000090600000..0x0000000092ffffff
>    3: 0x0000000093000000..0x00000000973fffff
>    4: 0x0000000097400000..0x00000000b71fffff
>    5: 0x00000000c0000000..0x00000000dfffffff
>    6: 0x00000000e2500000..0x00000000f87fffff
>    7: 0x00000000f8800000..0x00000000fa7fffff
>    8: 0x00000000fa800000..0x00000000fd3effff
>    9: 0x00000000fd3f0000..0x00000000fd3fefff
>   10: 0x00000000fd3ff000..0x00000000fd7fffff
>   11: 0x00000000fd800000..0x00000000fd901fff
>   12: 0x00000000fd902000..0x00000000fd909fff
>   13: 0x00000000fd90a000..0x00000000fd90bfff
>   14: 0x00000000fd90c000..0x00000000ffffffff
>   15: 0x0000000880000000..0x0000000affffffff
> 
> So we can add flags and nid to this debugfs.
> 
> For example,
> cat /sys/kernel/debug/memblock/memory
>    0: 0x0000000080000000..0x00000000901fffff    0 NONE
>    1: 0x0000000090200000..0x00000000905fffff    0 NOMAP
>    2: 0x0000000090600000..0x0000000092ffffff    0 NONE
>    3: 0x0000000093000000..0x00000000973fffff    0 NOMAP
>    4: 0x0000000097400000..0x00000000b71fffff    0 NONE
>    5: 0x00000000c0000000..0x00000000dfffffff    0 NONE
>    6: 0x00000000e2500000..0x00000000f87fffff    0 NONE
>    7: 0x00000000f8800000..0x00000000fa7fffff    0 NOMAP
>    8: 0x00000000fa800000..0x00000000fd3effff    0 NONE
>    9: 0x00000000fd3f0000..0x00000000fd3fefff    0 NOMAP
>   10: 0x00000000fd3ff000..0x00000000fd7fffff    0 NONE
>   11: 0x00000000fd800000..0x00000000fd901fff    0 NOMAP
>   12: 0x00000000fd902000..0x00000000fd909fff    0 NONE
>   13: 0x00000000fd90a000..0x00000000fd90bfff    0 NOMAP
>   14: 0x00000000fd90c000..0x00000000ffffffff    0 NONE
>   15: 0x0000000880000000..0x0000000affffffff    0 NONE
> 
> Signed-off-by: Yuwei Guan <ssawgyw@...il.com>
> ---
> v4:
> - show string value for each memblock flag
> ---
>  mm/memblock.c | 24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 511d4783dcf1..10d0ddbeebc1 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -2136,12 +2136,19 @@ void __init memblock_free_all(void)
>  }
>  
>  #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK)
> +static const char * const flagname[] = {
> +	[ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",
> +	[ilog2(MEMBLOCK_MIRROR)] = "MIRROR",
> +	[ilog2(MEMBLOCK_NOMAP)] = "NOMAP",
> +	[ilog2(MEMBLOCK_DRIVER_MANAGED)] = "DRV_MNG",
> +};
>  
>  static int memblock_debug_show(struct seq_file *m, void *private)
>  {
>  	struct memblock_type *type = m->private;
>  	struct memblock_region *reg;
> -	int i;
> +	int i, j;
> +	unsigned int count = ARRAY_SIZE(flagname);
>  	phys_addr_t end;
>  
>  	for (i = 0; i < type->cnt; i++) {
> @@ -2149,7 +2156,20 @@ static int memblock_debug_show(struct seq_file *m, void *private)
>  		end = reg->base + reg->size - 1;
>  
>  		seq_printf(m, "%4d: ", i);
> -		seq_printf(m, "%pa..%pa\n", &reg->base, &end);
> +		seq_printf(m, "%pa..%pa ", &reg->base, &end);
> +		seq_printf(m, "%4d ", memblock_get_region_node(reg));

As Kefeng mentioned, the node id for reserved regions will be wrong, so
this needs to be updated so that when reg->nid == MAX_NUMNODES we'll print
e.g. 'x'. 

> +		if (reg->flags) {
> +			for (j = 0; j < count; j++) {
> +				if (reg->flags & (1U << j)) {
> +					seq_printf(m, "%s\n", flagname[j]);
> +					break;
> +				}
> +			}
> +			if (j == count)
> +				seq_printf(m, "%s\n", "UNKNOWN");
> +		} else {
> +			seq_printf(m, "%s\n", "NONE");
> +		}
>  	}
>  	return 0;
>  }
> -- 
> 2.34.1
> 

-- 
Sincerely yours,
Mike.