linux-kernel - [PATCH] kdump: Defer the insertion of crashkernel resources

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Message-Id: <20231229080213.2622204-1-chenhuacai@loongson.cn>
Date: Fri, 29 Dec 2023 16:02:13 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Baoquan He <bhe@...hat.com>
Cc: Vivek Goyal <vgoyal@...hat.com>,
	Dave Young <dyoung@...hat.com>,
	Youling Tang <tangyouling@...inos.cn>,
	kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] kdump: Defer the insertion of crashkernel resources

In /proc/iomem, sub-regions should be inserted after their parent,
otherwise the insertion of parent resource fails. But after generic
crashkernel reservation applied, in both RISC-V and ARM64 (LoongArch
will also use generic reservation later on), crashkernel resources are
inserted before their parent, which causes the parent disappear in
/proc/iomem. So we defer the insertion of crashkernel resources to an
early_initcall().

1, Without 'crashkernel' parameter:

 100d0100-100d01ff : LOON0001:00
   100d0100-100d01ff : LOON0001:00 LOON0001:00
 100e0000-100e0bff : LOON0002:00
   100e0000-100e0bff : LOON0002:00 LOON0002:00
 1fe001e0-1fe001e7 : serial
 90400000-fa17ffff : System RAM
   f6220000-f622ffff : Reserved
   f9ee0000-f9ee3fff : Reserved
   fa120000-fa17ffff : Reserved
 fa190000-fe0bffff : System RAM
   fa190000-fa1bffff : Reserved
 fe4e0000-47fffffff : System RAM
   43c000000-441ffffff : Reserved
   47ff98000-47ffa3fff : Reserved
   47ffa4000-47ffa7fff : Reserved
   47ffa8000-47ffabfff : Reserved
   47ffac000-47ffaffff : Reserved
   47ffb0000-47ffb3fff : Reserved

2, With 'crashkernel' parameter, before this patch:

 100d0100-100d01ff : LOON0001:00
   100d0100-100d01ff : LOON0001:00 LOON0001:00
 100e0000-100e0bff : LOON0002:00
   100e0000-100e0bff : LOON0002:00 LOON0002:00
 1fe001e0-1fe001e7 : serial
 e6200000-f61fffff : Crash kernel
 fa190000-fe0bffff : System RAM
   fa190000-fa1bffff : Reserved
 fe4e0000-47fffffff : System RAM
   43c000000-441ffffff : Reserved
   47ff98000-47ffa3fff : Reserved
   47ffa4000-47ffa7fff : Reserved
   47ffa8000-47ffabfff : Reserved
   47ffac000-47ffaffff : Reserved
   47ffb0000-47ffb3fff : Reserved

3, With 'crashkernel' parameter, after this patch:

 100d0100-100d01ff : LOON0001:00
   100d0100-100d01ff : LOON0001:00 LOON0001:00
 100e0000-100e0bff : LOON0002:00
   100e0000-100e0bff : LOON0002:00 LOON0002:00
 1fe001e0-1fe001e7 : serial
 90400000-fa17ffff : System RAM
   e6200000-f61fffff : Crash kernel
   f6220000-f622ffff : Reserved
   f9ee0000-f9ee3fff : Reserved
   fa120000-fa17ffff : Reserved
 fa190000-fe0bffff : System RAM
   fa190000-fa1bffff : Reserved
 fe4e0000-47fffffff : System RAM
   43c000000-441ffffff : Reserved
   47ff98000-47ffa3fff : Reserved
   47ffa4000-47ffa7fff : Reserved
   47ffa8000-47ffabfff : Reserved
   47ffac000-47ffaffff : Reserved
   47ffb0000-47ffb3fff : Reserved

Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 kernel/crash_core.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index d4313b53837e..755d8d4ef5b0 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -377,7 +377,6 @@ static int __init reserve_crashkernel_low(unsigned long long low_size)
 
 	crashk_low_res.start = low_base;
 	crashk_low_res.end   = low_base + low_size - 1;
-	insert_resource(&iomem_resource, &crashk_low_res);
 #endif
 	return 0;
 }
@@ -459,8 +458,19 @@ void __init reserve_crashkernel_generic(char *cmdline,
 
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
-	insert_resource(&iomem_resource, &crashk_res);
 }
+
+static __init int insert_crashkernel_resources(void)
+{
+	if (crashk_res.start < crashk_res.end)
+		insert_resource(&iomem_resource, &crashk_res);
+
+	if (crashk_low_res.start < crashk_low_res.end)
+		insert_resource(&iomem_resource, &crashk_low_res);
+
+	return 0;
+}
+early_initcall(insert_crashkernel_resources);
 #endif
 
 int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
-- 
2.39.3