[PATCH v5 4/8] of: reserved_mem: mark /memreserve/ entries as MEMBLOCK_NODUMP

From: Wandun Chen <chenwandun1@gmail.com>
To: catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org,
	pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	robh@kernel.org, saravanak@kernel.org, rppt@kernel.org,
	baoquan.he@linux.dev, pasha.tatashin@soleen.com,
	pratyush@kernel.org, m.szyprowski@samsung.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
	linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
	linux-mm@kvack.org, kexec@lists.infradead.org,
	iommu@lists.linux.dev
Cc: kernel@xen0n.name, alex@ghiti.fr, akpm@linux-foundation.org,
	ruirui.yang@linux.dev, robin.murphy@arm.com
Subject: [PATCH v5 4/8] of: reserved_mem: mark /memreserve/ entries as MEMBLOCK_NODUMP
Date: Thu,  6 Aug 2026 17:35:15 +0800	[thread overview]
Message-ID: <20260806093519.2907771-5-chenwandun1@gmail.com> (raw)
In-Reply-To: <20260806093519.2907771-1-chenwandun1@gmail.com>

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>
---
 drivers/of/fdt.c             |  2 ++
 drivers/of/of_private.h      |  1 +
 drivers/of/of_reserved_mem.c | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index a64afc3ded3d..2aa888997e9b 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1286,6 +1286,8 @@ void __init unflatten_device_tree(void)
 	/* Save the statically-placed regions in the reserved_mem array */
 	fdt_scan_reserved_mem_late();
 
+	fdt_mark_memreserve_nodump();
+
 	/* Populate an empty root node when bootloader doesn't provide one */
 	if (!fdt) {
 		fdt = (void *) __dtb_empty_root_begin;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 0ae16da066e2..667ce9e46aab 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -187,6 +187,7 @@ 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_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 f38d11df6f15..f0683b5d77b3 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -251,6 +251,38 @@ 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 < rmem->base + rmem->size &&
+			    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.
-- 
2.43.0

