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

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Message-ID: <20230523160539.GH4967@kernel.org>
Date:   Tue, 23 May 2023 19:05:39 +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,

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));
> +		if (reg->flags) {
> +			for (j = 0; j < count; j++) {
> +				if (reg->flags & (1U << j)) {
> +					seq_printf(m, "%s\n", flagname[j]);
> +					break;

The flags are mostly mutually exclusive because it's unlikely they are used
together, but not because there are some restrictions on possible flags
combinations. So generally it's possible to have multiple flags set on the
same region.

Sorry, I missed that in v3.

> +				}
> +			}
> +			if (j == count)
> +				seq_printf(m, "%s\n", "UNKNOWN");
> +		} else {
> +			seq_printf(m, "%s\n", "NONE");
> +		}
>  	}
>  	return 0;
>  }
> -- 
> 2.34.1
> 

-- 
Sincerely yours,
Mike.