Re: [PATCH v6 05/10] crash_core: replace for_each_mem_range() with for_each_mem_region()

From: Baoquan He <baoquan.he@linux.dev>
To: Wandun Chen <chenwandun1@gmail.com>
Cc: catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org,
	pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
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	ruirui.yang@linux.dev, robin.murphy@arm.com,
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Subject: Re: [PATCH v6 05/10] crash_core: replace for_each_mem_range() with for_each_mem_region()
Date: Fri, 18 Sep 2026 16:04:33 +0800	[thread overview]
Message-ID: <aqzwkVldaBWcMojx@fedora> (raw)
In-Reply-To: <20260902073116.802752-6-chenwandun1@gmail.com>

On 09/02/26 at 03:31pm, Wandun Chen wrote:
> From: Wandun Chen <chenwandun@lixiang.com>
> 
> for_each_mem_range() skips MEMBLOCK_NOMAP regions implicitly. Switch the
> weak defaults to for_each_mem_region(), which exposes struct
> memblock_region and per-region flags, and filter NOMAP regions explicitly
> via the new crash_should_skip_region() helper. This prepares for a
> subsequent patch to extend the skip filter.
> 
> No functional change.
> 
> Signed-off-by: Wandun Chen <chenwandun@lixiang.com>
> Tested-by: Meijing Zhao <zhaomeijing@lixiang.com>
> ---
>  kernel/crash_core.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)

Acked-by: Baoquan He <baoquan.he@linux.dev>

> 
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 3adee1ae120c..bd64cf585795 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -270,6 +270,12 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  	return 0;
>  }
>  
> +/* Exclude NOMAP regions from the vmcore. */
> +static bool crash_should_skip_region(struct memblock_region *reg)
> +{
> +	return memblock_is_nomap(reg);
> +}
> +
>  static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
>  {
>  	struct crash_mem *cmem;
> @@ -285,22 +291,25 @@ static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
>  unsigned int __weak arch_get_system_nr_ranges(void)
>  {
>  	unsigned int nr_ranges = 2 + crashk_cma_cnt; /* crashk_res + crashk_low_res, +CMA splits */
> -	phys_addr_t start, end;
> -	u64 i;
> +	struct memblock_region *reg;
>  
> -	for_each_mem_range(i, &start, &end)
> +	for_each_mem_region(reg) {
> +		if (crash_should_skip_region(reg))
> +			continue;
>  		nr_ranges++;
> +	}
>  	return nr_ranges;
>  }
>  
>  int __weak arch_crash_populate_cmem(struct crash_mem *cmem)
>  {
> -	phys_addr_t start, end;
> -	u64 i;
> +	struct memblock_region *reg;
>  
> -	for_each_mem_range(i, &start, &end) {
> -		cmem->ranges[cmem->nr_ranges].start = start;
> -		cmem->ranges[cmem->nr_ranges].end = end - 1;
> +	for_each_mem_region(reg) {
> +		if (crash_should_skip_region(reg))
> +			continue;
> +		cmem->ranges[cmem->nr_ranges].start = reg->base;
> +		cmem->ranges[cmem->nr_ranges].end = reg->base + reg->size - 1;
>  		cmem->nr_ranges++;
>  	}
>  	return 0;
> -- 
> 2.43.0
>