Re: [PATCH v6 09/10] of: reserved_mem: mark /memreserve/ entries as MEMBLOCK_NODUMP

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 02.09.2026 09:31, Wandun Chen wrote:
> From: Wandun Chen <chenwandun@lixiang.com>
>
> The /memreserve/ entries are memory reservations made by the bootloader
> or firmware, their contents are not needed for kernel crash analysis,
> so mark them MEMBLOCK_NODUMP to have kdump omit them from the vmcore.
>
> Entries that overlap a dumpable region (such as CMA) are left unmarked,
> because the pages of a dumpable region may carry crash-relevant data.
>
> Signed-off-by: Wandun Chen <chenwandun@lixiang.com>
> Tested-by: Meijing Zhao <zhaomeijing@lixiang.com>

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>  drivers/of/fdt.c             |  1 +
>  drivers/of/of_private.h      |  1 +
>  drivers/of/of_reserved_mem.c | 33 +++++++++++++++++++++++++++++++++
>  3 files changed, 35 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 286fd4db6312..9a727941b5af 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1286,6 +1286,7 @@ void __init unflatten_device_tree(void)
>  	/* Save the statically-placed regions in the reserved_mem array */
>  	fdt_scan_reserved_mem_late();
>  	fdt_mark_reserve_mem_nodump();
> +	fdt_mark_memreserve_nodump();
>  
>  	/* Populate an empty root node when bootloader doesn't provide one */
>  	if (!fdt) {
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index 505735732c13..6497404ec751 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -188,6 +188,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
>  int fdt_scan_reserved_mem(void);
>  void __init fdt_scan_reserved_mem_late(void);
>  void __init fdt_mark_reserve_mem_nodump(void);
> +void __init fdt_mark_memreserve_nodump(void);
>  
>  bool of_fdt_device_is_available(const void *blob, unsigned long node);
>  
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index f29a07e8fb23..a42cf6eac55b 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -251,6 +251,39 @@ static void __init __rmem_check_for_overlap(void)
>  	}
>  }
>  
> +void __init fdt_mark_memreserve_nodump(void)
> +{
> +	u64 base, size;
> +	int n;
> +	const void *fdt = initial_boot_params;
> +
> +	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
> +		return;
> +
> +	if (!fdt)
> +		return;
> +
> +	for (n = 0; ; n++) {
> +		int i;
> +
> +		if (fdt_get_mem_rsv(fdt, n, &base, &size))
> +			break;
> +		if (!size)
> +			break;
> +
> +		for (i = 0; i < reserved_mem_count; i++) {
> +			struct reserved_mem *rmem = &reserved_mem[i];
> +
> +			if (rmem->dumpable &&
> +			    base < (u64)rmem->base + (u64)rmem->size &&
> +			    (u64)rmem->base < base + size)
> +				break;
> +		}
> +		if (i == reserved_mem_count)
> +			memblock_mark_nodump(base, size);
> +	}
> +}
> +
>  /**
>   * fdt_scan_reserved_mem_late() - Scan FDT and initialize remaining reserved
>   * memory regions.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland