[PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[Chen Zhou]

This patch series enable reserving crashkernel above 4G in arm64.

There are following issues in arm64 kdump:
1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
when there is no enough low memory.
2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
in this case, if swiotlb or DMA buffers are required, crash dump kernel
will boot failure because there is no low memory available for allocation.
3. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken
the arm64 kdump. If the memory reserved for crash dump kernel falled in
ZONE_DMA32, the devices in crash dump kernel need to use ZONE_DMA will alloc
fail.

To solve these issues, introduce crashkernel=X,low to reserve specified
size low memory.
Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

When crashkernel is reserved above 4G in memory and crashkernel=X,low
is specified simultaneously, kernel should reserve specified size low memory
for crash dump kernel devices. So there may be two crash kernel regions, one
is below 4G, the other is above 4G.
In order to distinct from the high region and make no effect to the use of
kexec-tools, rename the low region as "Crash kernel (low)", and pass the
low region by reusing DT property "linux,usable-memory-range". We made the low
memory region as the last range of "linux,usable-memory-range" to keep
compatibility with existing user-space and older kdump kernels.

Besides, we need to modify kexec-tools:
arm64: support more than one crash kernel regions(see [1])

Another update is document about DT property 'linux,usable-memory-range':
schemas: update 'linux,usable-memory-range' node schema(see [2])

The previous changes and discussions can be retrieved from:

Changes since [v8]
- Reuse DT property "linux,usable-memory-range".
Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low
memory region.
- Fix kdump broken with ZONE_DMA reintroduced.
- Update chosen schema.

Changes since [v7]
- Move x86 CRASH_ALIGN to 2M
Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M.
- Update Documentation/devicetree/bindings/chosen.txt.
Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt
suggested by Arnd.
- Add Tested-by from Jhon and pk.

Changes since [v6]
- Fix build errors reported by kbuild test robot.

Changes since [v5]
- Move reserve_crashkernel_low() into kernel/crash_core.c.
- Delete crashkernel=X,high.
- Modify crashkernel=X,low.
If crashkernel=X,low is specified simultaneously, reserve spcified size low
memory for crash kdump kernel devices firstly and then reserve memory above 4G.
In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
pass to crash dump kernel by DT property "linux,low-memory-range".
- Update Documentation/admin-guide/kdump/kdump.rst.

Changes since [v4]
- Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.

Changes since [v3]
- Add memblock_cap_memory_ranges back for multiple ranges.
- Fix some compiling warnings.

Changes since [v2]
- Split patch "arm64: kdump: support reserving crashkernel above 4G" as
two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
patch.

Changes since [v1]:
- Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
- Remove memblock_cap_memory_ranges() i added in v1 and implement that
in fdt_enforce_memory_region().
There are at most two crash kernel regions, for two crash kernel regions
case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
and then remove the memory range in the middle.

[1]: http://lists.infradead.org/pipermail/kexec/2020-June/020737.html
[2]: https://github.com/robherring/dt-schema/pull/19 
[v1]: https://lkml.org/lkml/2019/4/2/1174
[v2]: https://lkml.org/lkml/2019/4/9/86
[v3]: https://lkml.org/lkml/2019/4/9/306
[v4]: https://lkml.org/lkml/2019/4/15/273
[v5]: https://lkml.org/lkml/2019/5/6/1360
[v6]: https://lkml.org/lkml/2019/8/30/142
[v7]: https://lkml.org/lkml/2019/12/23/411
[v8]: https://lkml.org/lkml/2020/5/21/213

Chen Zhou (5):
  x86: kdump: move reserve_crashkernel_low() into crash_core.c
  arm64: kdump: reserve crashkenel above 4G for crash dump kernel
  arm64: kdump: add memory for devices by DT property
    linux,usable-memory-range
  arm64: kdump: fix kdump broken with ZONE_DMA reintroduced
  kdump: update Documentation about crashkernel on arm64

 Documentation/admin-guide/kdump/kdump.rst     | 13 ++-
 .../admin-guide/kernel-parameters.txt         | 17 +++-
 arch/arm64/kernel/setup.c                     |  8 +-
 arch/arm64/mm/init.c                          | 74 ++++++++++++---
 arch/x86/kernel/setup.c                       | 66 ++------------
 include/linux/crash_core.h                    |  3 +
 include/linux/kexec.h                         |  2 -
 kernel/crash_core.c                           | 90 +++++++++++++++++++
 kernel/kexec_core.c                           | 17 ----
 9 files changed, 196 insertions(+), 94 deletions(-)

-- 
2.20.1

[PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[Chen Zhou]

This patch series enable reserving crashkernel above 4G in arm64.

There are following issues in arm64 kdump:
1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
when there is no enough low memory.
2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
in this case, if swiotlb or DMA buffers are required, crash dump kernel
will boot failure because there is no low memory available for allocation.
3. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken
the arm64 kdump. If the memory reserved for crash dump kernel falled in
ZONE_DMA32, the devices in crash dump kernel need to use ZONE_DMA will alloc
fail.

To solve these issues, introduce crashkernel=X,low to reserve specified
size low memory.
Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

When crashkernel is reserved above 4G in memory and crashkernel=X,low
is specified simultaneously, kernel should reserve specified size low memory
for crash dump kernel devices. So there may be two crash kernel regions, one
is below 4G, the other is above 4G.
In order to distinct from the high region and make no effect to the use of
kexec-tools, rename the low region as "Crash kernel (low)", and pass the
low region by reusing DT property "linux,usable-memory-range". We made the low
memory region as the last range of "linux,usable-memory-range" to keep
compatibility with existing user-space and older kdump kernels.

Besides, we need to modify kexec-tools:
arm64: support more than one crash kernel regions(see [1])

Another update is document about DT property 'linux,usable-memory-range':
schemas: update 'linux,usable-memory-range' node schema(see [2])

The previous changes and discussions can be retrieved from:

Changes since [v8]
- Reuse DT property "linux,usable-memory-range".
Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low
memory region.
- Fix kdump broken with ZONE_DMA reintroduced.
- Update chosen schema.

Changes since [v7]
- Move x86 CRASH_ALIGN to 2M
Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M.
- Update Documentation/devicetree/bindings/chosen.txt.
Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt
suggested by Arnd.
- Add Tested-by from Jhon and pk.

Changes since [v6]
- Fix build errors reported by kbuild test robot.

Changes since [v5]
- Move reserve_crashkernel_low() into kernel/crash_core.c.
- Delete crashkernel=X,high.
- Modify crashkernel=X,low.
If crashkernel=X,low is specified simultaneously, reserve spcified size low
memory for crash kdump kernel devices firstly and then reserve memory above 4G.
In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
pass to crash dump kernel by DT property "linux,low-memory-range".
- Update Documentation/admin-guide/kdump/kdump.rst.

Changes since [v4]
- Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.

Changes since [v3]
- Add memblock_cap_memory_ranges back for multiple ranges.
- Fix some compiling warnings.

Changes since [v2]
- Split patch "arm64: kdump: support reserving crashkernel above 4G" as
two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
patch.

Changes since [v1]:
- Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
- Remove memblock_cap_memory_ranges() i added in v1 and implement that
in fdt_enforce_memory_region().
There are at most two crash kernel regions, for two crash kernel regions
case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
and then remove the memory range in the middle.

[1]: http://lists.infradead.org/pipermail/kexec/2020-June/020737.html
[2]: https://github.com/robherring/dt-schema/pull/19 
[v1]: https://lkml.org/lkml/2019/4/2/1174
[v2]: https://lkml.org/lkml/2019/4/9/86
[v3]: https://lkml.org/lkml/2019/4/9/306
[v4]: https://lkml.org/lkml/2019/4/15/273
[v5]: https://lkml.org/lkml/2019/5/6/1360
[v6]: https://lkml.org/lkml/2019/8/30/142
[v7]: https://lkml.org/lkml/2019/12/23/411
[v8]: https://lkml.org/lkml/2020/5/21/213

Chen Zhou (5):
  x86: kdump: move reserve_crashkernel_low() into crash_core.c
  arm64: kdump: reserve crashkenel above 4G for crash dump kernel
  arm64: kdump: add memory for devices by DT property
    linux,usable-memory-range
  arm64: kdump: fix kdump broken with ZONE_DMA reintroduced
  kdump: update Documentation about crashkernel on arm64

 Documentation/admin-guide/kdump/kdump.rst     | 13 ++-
 .../admin-guide/kernel-parameters.txt         | 17 +++-
 arch/arm64/kernel/setup.c                     |  8 +-
 arch/arm64/mm/init.c                          | 74 ++++++++++++---
 arch/x86/kernel/setup.c                       | 66 ++------------
 include/linux/crash_core.h                    |  3 +
 include/linux/kexec.h                         |  2 -
 kernel/crash_core.c                           | 90 +++++++++++++++++++
 kernel/kexec_core.c                           | 17 ----
 9 files changed, 196 insertions(+), 94 deletions(-)

-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[Chen Zhou]

This patch series enable reserving crashkernel above 4G in arm64.

There are following issues in arm64 kdump:
1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
when there is no enough low memory.
2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
in this case, if swiotlb or DMA buffers are required, crash dump kernel
will boot failure because there is no low memory available for allocation.
3. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken
the arm64 kdump. If the memory reserved for crash dump kernel falled in
ZONE_DMA32, the devices in crash dump kernel need to use ZONE_DMA will alloc
fail.

To solve these issues, introduce crashkernel=X,low to reserve specified
size low memory.
Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

When crashkernel is reserved above 4G in memory and crashkernel=X,low
is specified simultaneously, kernel should reserve specified size low memory
for crash dump kernel devices. So there may be two crash kernel regions, one
is below 4G, the other is above 4G.
In order to distinct from the high region and make no effect to the use of
kexec-tools, rename the low region as "Crash kernel (low)", and pass the
low region by reusing DT property "linux,usable-memory-range". We made the low
memory region as the last range of "linux,usable-memory-range" to keep
compatibility with existing user-space and older kdump kernels.

Besides, we need to modify kexec-tools:
arm64: support more than one crash kernel regions(see [1])

Another update is document about DT property 'linux,usable-memory-range':
schemas: update 'linux,usable-memory-range' node schema(see [2])

The previous changes and discussions can be retrieved from:

Changes since [v8]
- Reuse DT property "linux,usable-memory-range".
Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low
memory region.
- Fix kdump broken with ZONE_DMA reintroduced.
- Update chosen schema.

Changes since [v7]
- Move x86 CRASH_ALIGN to 2M
Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M.
- Update Documentation/devicetree/bindings/chosen.txt.
Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt
suggested by Arnd.
- Add Tested-by from Jhon and pk.

Changes since [v6]
- Fix build errors reported by kbuild test robot.

Changes since [v5]
- Move reserve_crashkernel_low() into kernel/crash_core.c.
- Delete crashkernel=X,high.
- Modify crashkernel=X,low.
If crashkernel=X,low is specified simultaneously, reserve spcified size low
memory for crash kdump kernel devices firstly and then reserve memory above 4G.
In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
pass to crash dump kernel by DT property "linux,low-memory-range".
- Update Documentation/admin-guide/kdump/kdump.rst.

Changes since [v4]
- Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.

Changes since [v3]
- Add memblock_cap_memory_ranges back for multiple ranges.
- Fix some compiling warnings.

Changes since [v2]
- Split patch "arm64: kdump: support reserving crashkernel above 4G" as
two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
patch.

Changes since [v1]:
- Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
- Remove memblock_cap_memory_ranges() i added in v1 and implement that
in fdt_enforce_memory_region().
There are at most two crash kernel regions, for two crash kernel regions
case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
and then remove the memory range in the middle.

[1]: http://lists.infradead.org/pipermail/kexec/2020-June/020737.html
[2]: https://github.com/robherring/dt-schema/pull/19 
[v1]: https://lkml.org/lkml/2019/4/2/1174
[v2]: https://lkml.org/lkml/2019/4/9/86
[v3]: https://lkml.org/lkml/2019/4/9/306
[v4]: https://lkml.org/lkml/2019/4/15/273
[v5]: https://lkml.org/lkml/2019/5/6/1360
[v6]: https://lkml.org/lkml/2019/8/30/142
[v7]: https://lkml.org/lkml/2019/12/23/411
[v8]: https://lkml.org/lkml/2020/5/21/213

Chen Zhou (5):
  x86: kdump: move reserve_crashkernel_low() into crash_core.c
  arm64: kdump: reserve crashkenel above 4G for crash dump kernel
  arm64: kdump: add memory for devices by DT property
    linux,usable-memory-range
  arm64: kdump: fix kdump broken with ZONE_DMA reintroduced
  kdump: update Documentation about crashkernel on arm64

 Documentation/admin-guide/kdump/kdump.rst     | 13 ++-
 .../admin-guide/kernel-parameters.txt         | 17 +++-
 arch/arm64/kernel/setup.c                     |  8 +-
 arch/arm64/mm/init.c                          | 74 ++++++++++++---
 arch/x86/kernel/setup.c                       | 66 ++------------
 include/linux/crash_core.h                    |  3 +
 include/linux/kexec.h                         |  2 -
 kernel/crash_core.c                           | 90 +++++++++++++++++++
 kernel/kexec_core.c                           | 17 ----
 9 files changed, 196 insertions(+), 94 deletions(-)

-- 
2.20.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v9 1/5] x86: kdump: move reserve_crashkernel_low() into crash_core.c

[Chen Zhou]

In preparation for supporting reserve_crashkernel_low in arm64 as
x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.

BTW, move x86_64 CRASH_ALIGN to 2M suggested by Dave. CONFIG_PHYSICAL_ALIGN
can be selected from 2M to 16M, move to the same as arm64.

Note, in arm64, we reserve low memory if and only if crashkernel=X,low
is specified. Different with x86_64, don't set low memory automatically.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/x86/kernel/setup.c    | 66 ++++-------------------------
 include/linux/crash_core.h |  3 ++
 include/linux/kexec.h      |  2 -
 kernel/crash_core.c        | 85 ++++++++++++++++++++++++++++++++++++++
 kernel/kexec_core.c        | 17 --------
 5 files changed, 96 insertions(+), 77 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a3767e74c758..33db99ae3035 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -401,8 +401,8 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 
 #ifdef CONFIG_KEXEC_CORE
 
-/* 16M alignment for crash kernel regions */
-#define CRASH_ALIGN		SZ_16M
+/* 2M alignment for crash kernel regions */
+#define CRASH_ALIGN		SZ_2M
 
 /*
  * Keep the crash kernel below this limit.
@@ -425,59 +425,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 # define CRASH_ADDR_HIGH_MAX	SZ_64T
 #endif
 
-static int __init reserve_crashkernel_low(void)
-{
-#ifdef CONFIG_X86_64
-	unsigned long long base, low_base = 0, low_size = 0;
-	unsigned long total_low_mem;
-	int ret;
-
-	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
-
-	/* crashkernel=Y,low */
-	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
-	if (ret) {
-		/*
-		 * two parts from kernel/dma/swiotlb.c:
-		 * -swiotlb size: user-specified with swiotlb= or default.
-		 *
-		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
-		 * to 8M for other buffers that may need to stay low too. Also
-		 * make sure we allocate enough extra low memory so that we
-		 * don't run out of DMA buffers for 32-bit devices.
-		 */
-		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
-	} else {
-		/* passed with crashkernel=0,low ? */
-		if (!low_size)
-			return 0;
-	}
-
-	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
-	if (!low_base) {
-		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
-		       (unsigned long)(low_size >> 20));
-		return -ENOMEM;
-	}
-
-	ret = memblock_reserve(low_base, low_size);
-	if (ret) {
-		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
-		return ret;
-	}
-
-	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
-		(unsigned long)(low_size >> 20),
-		(unsigned long)(low_base >> 20),
-		(unsigned long)(total_low_mem >> 20));
-
-	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;
-}
-
 static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_size, crash_base, total_mem;
@@ -541,9 +488,12 @@ static void __init reserve_crashkernel(void)
 		return;
 	}
 
-	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
-		memblock_free(crash_base, crash_size);
-		return;
+	if (crash_base >= (1ULL << 32)) {
+		if (reserve_crashkernel_low()) {
+			memblock_free(crash_base, crash_size);
+			return;
+		}
+		insert_resource(&iomem_resource, &crashk_low_res);
 	}
 
 	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 525510a9f965..4df8c0bff03e 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -63,6 +63,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
 extern unsigned char *vmcoreinfo_data;
 extern size_t vmcoreinfo_size;
 extern u32 *vmcoreinfo_note;
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
 
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
@@ -74,5 +76,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
+int __init reserve_crashkernel_low(void);
 
 #endif /* LINUX_CRASH_CORE_H */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ea67910ae6b7..a460afdbab0f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -330,8 +330,6 @@ extern int kexec_load_disabled;
 
 /* Location of a reserved region to hold the crash kernel.
  */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
 extern note_buf_t __percpu *crash_notes;
 
 /* flag to track if kexec reboot is in progress */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 9f1557b98468..a7580d291c37 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -7,6 +7,8 @@
 #include <linux/crash_core.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
+#include <linux/memblock.h>
+#include <linux/swiotlb.h>
 
 #include <asm/page.h>
 #include <asm/sections.h>
@@ -19,6 +21,22 @@ u32 *vmcoreinfo_note;
 /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
 static unsigned char *vmcoreinfo_data_safecopy;
 
+/* Location of the reserved area for the crash kernel */
+struct resource crashk_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+struct resource crashk_low_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+
 /*
  * parsing the "crashkernel" commandline
  *
@@ -292,6 +310,73 @@ int __init parse_crashkernel_low(char *cmdline,
 				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
 }
 
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+#define CRASH_ALIGN		SZ_2M
+#endif
+
+int __init reserve_crashkernel_low(void)
+{
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+	unsigned long long base, low_base = 0, low_size = 0;
+	unsigned long total_low_mem;
+	int ret;
+
+	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
+
+	/* crashkernel=Y,low */
+	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
+			&base);
+	if (ret) {
+#ifdef CONFIG_X86_64
+		/*
+		 * two parts from lib/swiotlb.c:
+		 * -swiotlb size: user-specified with swiotlb= or default.
+		 *
+		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
+		 * to 8M for other buffers that may need to stay low too. Also
+		 * make sure we allocate enough extra low memory so that we
+		 * don't run out of DMA buffers for 32-bit devices.
+		 */
+		low_size = max(swiotlb_size_or_default() + (8UL << 20),
+				256UL << 20);
+#else
+		/*
+		 * in arm64, reserve low memory if and only if crashkernel=X,low
+		 * specified.
+		 */
+		return -EINVAL;
+#endif
+	} else {
+		/* passed with crashkernel=0,low ? */
+		if (!low_size)
+			return 0;
+	}
+
+	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+	if (!low_base) {
+		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
+		       (unsigned long)(low_size >> 20));
+		return -ENOMEM;
+	}
+
+	ret = memblock_reserve(low_base, low_size);
+	if (ret) {
+		pr_err("%s: Error reserving crashkernel low memblock.\n",
+				__func__);
+		return ret;
+	}
+
+	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
+		(unsigned long)(low_size >> 20),
+		(unsigned long)(low_base >> 20),
+		(unsigned long)(total_low_mem >> 20));
+
+	crashk_low_res.start = low_base;
+	crashk_low_res.end   = low_base + low_size - 1;
+#endif
+	return 0;
+}
+
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)
 {
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index c19c0dad1ebe..db66bbabfff3 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
 
-
-/* Location of the reserved area for the crash kernel */
-struct resource crashk_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-struct resource crashk_low_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-
 int kexec_should_crash(struct task_struct *p)
 {
 	/*
-- 
2.20.1

[PATCH v9 1/5] x86: kdump: move reserve_crashkernel_low() into crash_core.c

[Chen Zhou]

In preparation for supporting reserve_crashkernel_low in arm64 as
x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.

BTW, move x86_64 CRASH_ALIGN to 2M suggested by Dave. CONFIG_PHYSICAL_ALIGN
can be selected from 2M to 16M, move to the same as arm64.

Note, in arm64, we reserve low memory if and only if crashkernel=X,low
is specified. Different with x86_64, don't set low memory automatically.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/x86/kernel/setup.c    | 66 ++++-------------------------
 include/linux/crash_core.h |  3 ++
 include/linux/kexec.h      |  2 -
 kernel/crash_core.c        | 85 ++++++++++++++++++++++++++++++++++++++
 kernel/kexec_core.c        | 17 --------
 5 files changed, 96 insertions(+), 77 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a3767e74c758..33db99ae3035 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -401,8 +401,8 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 
 #ifdef CONFIG_KEXEC_CORE
 
-/* 16M alignment for crash kernel regions */
-#define CRASH_ALIGN		SZ_16M
+/* 2M alignment for crash kernel regions */
+#define CRASH_ALIGN		SZ_2M
 
 /*
  * Keep the crash kernel below this limit.
@@ -425,59 +425,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 # define CRASH_ADDR_HIGH_MAX	SZ_64T
 #endif
 
-static int __init reserve_crashkernel_low(void)
-{
-#ifdef CONFIG_X86_64
-	unsigned long long base, low_base = 0, low_size = 0;
-	unsigned long total_low_mem;
-	int ret;
-
-	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
-
-	/* crashkernel=Y,low */
-	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
-	if (ret) {
-		/*
-		 * two parts from kernel/dma/swiotlb.c:
-		 * -swiotlb size: user-specified with swiotlb= or default.
-		 *
-		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
-		 * to 8M for other buffers that may need to stay low too. Also
-		 * make sure we allocate enough extra low memory so that we
-		 * don't run out of DMA buffers for 32-bit devices.
-		 */
-		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
-	} else {
-		/* passed with crashkernel=0,low ? */
-		if (!low_size)
-			return 0;
-	}
-
-	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
-	if (!low_base) {
-		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
-		       (unsigned long)(low_size >> 20));
-		return -ENOMEM;
-	}
-
-	ret = memblock_reserve(low_base, low_size);
-	if (ret) {
-		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
-		return ret;
-	}
-
-	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
-		(unsigned long)(low_size >> 20),
-		(unsigned long)(low_base >> 20),
-		(unsigned long)(total_low_mem >> 20));
-
-	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;
-}
-
 static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_size, crash_base, total_mem;
@@ -541,9 +488,12 @@ static void __init reserve_crashkernel(void)
 		return;
 	}
 
-	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
-		memblock_free(crash_base, crash_size);
-		return;
+	if (crash_base >= (1ULL << 32)) {
+		if (reserve_crashkernel_low()) {
+			memblock_free(crash_base, crash_size);
+			return;
+		}
+		insert_resource(&iomem_resource, &crashk_low_res);
 	}
 
 	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 525510a9f965..4df8c0bff03e 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -63,6 +63,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
 extern unsigned char *vmcoreinfo_data;
 extern size_t vmcoreinfo_size;
 extern u32 *vmcoreinfo_note;
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
 
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
@@ -74,5 +76,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
+int __init reserve_crashkernel_low(void);
 
 #endif /* LINUX_CRASH_CORE_H */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ea67910ae6b7..a460afdbab0f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -330,8 +330,6 @@ extern int kexec_load_disabled;
 
 /* Location of a reserved region to hold the crash kernel.
  */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
 extern note_buf_t __percpu *crash_notes;
 
 /* flag to track if kexec reboot is in progress */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 9f1557b98468..a7580d291c37 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -7,6 +7,8 @@
 #include <linux/crash_core.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
+#include <linux/memblock.h>
+#include <linux/swiotlb.h>
 
 #include <asm/page.h>
 #include <asm/sections.h>
@@ -19,6 +21,22 @@ u32 *vmcoreinfo_note;
 /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
 static unsigned char *vmcoreinfo_data_safecopy;
 
+/* Location of the reserved area for the crash kernel */
+struct resource crashk_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+struct resource crashk_low_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+
 /*
  * parsing the "crashkernel" commandline
  *
@@ -292,6 +310,73 @@ int __init parse_crashkernel_low(char *cmdline,
 				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
 }
 
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+#define CRASH_ALIGN		SZ_2M
+#endif
+
+int __init reserve_crashkernel_low(void)
+{
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+	unsigned long long base, low_base = 0, low_size = 0;
+	unsigned long total_low_mem;
+	int ret;
+
+	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
+
+	/* crashkernel=Y,low */
+	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
+			&base);
+	if (ret) {
+#ifdef CONFIG_X86_64
+		/*
+		 * two parts from lib/swiotlb.c:
+		 * -swiotlb size: user-specified with swiotlb= or default.
+		 *
+		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
+		 * to 8M for other buffers that may need to stay low too. Also
+		 * make sure we allocate enough extra low memory so that we
+		 * don't run out of DMA buffers for 32-bit devices.
+		 */
+		low_size = max(swiotlb_size_or_default() + (8UL << 20),
+				256UL << 20);
+#else
+		/*
+		 * in arm64, reserve low memory if and only if crashkernel=X,low
+		 * specified.
+		 */
+		return -EINVAL;
+#endif
+	} else {
+		/* passed with crashkernel=0,low ? */
+		if (!low_size)
+			return 0;
+	}
+
+	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+	if (!low_base) {
+		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
+		       (unsigned long)(low_size >> 20));
+		return -ENOMEM;
+	}
+
+	ret = memblock_reserve(low_base, low_size);
+	if (ret) {
+		pr_err("%s: Error reserving crashkernel low memblock.\n",
+				__func__);
+		return ret;
+	}
+
+	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
+		(unsigned long)(low_size >> 20),
+		(unsigned long)(low_base >> 20),
+		(unsigned long)(total_low_mem >> 20));
+
+	crashk_low_res.start = low_base;
+	crashk_low_res.end   = low_base + low_size - 1;
+#endif
+	return 0;
+}
+
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)
 {
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index c19c0dad1ebe..db66bbabfff3 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
 
-
-/* Location of the reserved area for the crash kernel */
-struct resource crashk_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-struct resource crashk_low_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-
 int kexec_should_crash(struct task_struct *p)
 {
 	/*
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v9 1/5] x86: kdump: move reserve_crashkernel_low() into crash_core.c

[Chen Zhou]

In preparation for supporting reserve_crashkernel_low in arm64 as
x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.

BTW, move x86_64 CRASH_ALIGN to 2M suggested by Dave. CONFIG_PHYSICAL_ALIGN
can be selected from 2M to 16M, move to the same as arm64.

Note, in arm64, we reserve low memory if and only if crashkernel=X,low
is specified. Different with x86_64, don't set low memory automatically.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/x86/kernel/setup.c    | 66 ++++-------------------------
 include/linux/crash_core.h |  3 ++
 include/linux/kexec.h      |  2 -
 kernel/crash_core.c        | 85 ++++++++++++++++++++++++++++++++++++++
 kernel/kexec_core.c        | 17 --------
 5 files changed, 96 insertions(+), 77 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a3767e74c758..33db99ae3035 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -401,8 +401,8 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 
 #ifdef CONFIG_KEXEC_CORE
 
-/* 16M alignment for crash kernel regions */
-#define CRASH_ALIGN		SZ_16M
+/* 2M alignment for crash kernel regions */
+#define CRASH_ALIGN		SZ_2M
 
 /*
  * Keep the crash kernel below this limit.
@@ -425,59 +425,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 # define CRASH_ADDR_HIGH_MAX	SZ_64T
 #endif
 
-static int __init reserve_crashkernel_low(void)
-{
-#ifdef CONFIG_X86_64
-	unsigned long long base, low_base = 0, low_size = 0;
-	unsigned long total_low_mem;
-	int ret;
-
-	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
-
-	/* crashkernel=Y,low */
-	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
-	if (ret) {
-		/*
-		 * two parts from kernel/dma/swiotlb.c:
-		 * -swiotlb size: user-specified with swiotlb= or default.
-		 *
-		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
-		 * to 8M for other buffers that may need to stay low too. Also
-		 * make sure we allocate enough extra low memory so that we
-		 * don't run out of DMA buffers for 32-bit devices.
-		 */
-		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
-	} else {
-		/* passed with crashkernel=0,low ? */
-		if (!low_size)
-			return 0;
-	}
-
-	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
-	if (!low_base) {
-		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
-		       (unsigned long)(low_size >> 20));
-		return -ENOMEM;
-	}
-
-	ret = memblock_reserve(low_base, low_size);
-	if (ret) {
-		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
-		return ret;
-	}
-
-	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
-		(unsigned long)(low_size >> 20),
-		(unsigned long)(low_base >> 20),
-		(unsigned long)(total_low_mem >> 20));
-
-	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;
-}
-
 static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_size, crash_base, total_mem;
@@ -541,9 +488,12 @@ static void __init reserve_crashkernel(void)
 		return;
 	}
 
-	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
-		memblock_free(crash_base, crash_size);
-		return;
+	if (crash_base >= (1ULL << 32)) {
+		if (reserve_crashkernel_low()) {
+			memblock_free(crash_base, crash_size);
+			return;
+		}
+		insert_resource(&iomem_resource, &crashk_low_res);
 	}
 
 	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 525510a9f965..4df8c0bff03e 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -63,6 +63,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
 extern unsigned char *vmcoreinfo_data;
 extern size_t vmcoreinfo_size;
 extern u32 *vmcoreinfo_note;
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
 
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
@@ -74,5 +76,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
+int __init reserve_crashkernel_low(void);
 
 #endif /* LINUX_CRASH_CORE_H */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ea67910ae6b7..a460afdbab0f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -330,8 +330,6 @@ extern int kexec_load_disabled;
 
 /* Location of a reserved region to hold the crash kernel.
  */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
 extern note_buf_t __percpu *crash_notes;
 
 /* flag to track if kexec reboot is in progress */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 9f1557b98468..a7580d291c37 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -7,6 +7,8 @@
 #include <linux/crash_core.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
+#include <linux/memblock.h>
+#include <linux/swiotlb.h>
 
 #include <asm/page.h>
 #include <asm/sections.h>
@@ -19,6 +21,22 @@ u32 *vmcoreinfo_note;
 /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
 static unsigned char *vmcoreinfo_data_safecopy;
 
+/* Location of the reserved area for the crash kernel */
+struct resource crashk_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+struct resource crashk_low_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+
 /*
  * parsing the "crashkernel" commandline
  *
@@ -292,6 +310,73 @@ int __init parse_crashkernel_low(char *cmdline,
 				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
 }
 
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+#define CRASH_ALIGN		SZ_2M
+#endif
+
+int __init reserve_crashkernel_low(void)
+{
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+	unsigned long long base, low_base = 0, low_size = 0;
+	unsigned long total_low_mem;
+	int ret;
+
+	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
+
+	/* crashkernel=Y,low */
+	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
+			&base);
+	if (ret) {
+#ifdef CONFIG_X86_64
+		/*
+		 * two parts from lib/swiotlb.c:
+		 * -swiotlb size: user-specified with swiotlb= or default.
+		 *
+		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
+		 * to 8M for other buffers that may need to stay low too. Also
+		 * make sure we allocate enough extra low memory so that we
+		 * don't run out of DMA buffers for 32-bit devices.
+		 */
+		low_size = max(swiotlb_size_or_default() + (8UL << 20),
+				256UL << 20);
+#else
+		/*
+		 * in arm64, reserve low memory if and only if crashkernel=X,low
+		 * specified.
+		 */
+		return -EINVAL;
+#endif
+	} else {
+		/* passed with crashkernel=0,low ? */
+		if (!low_size)
+			return 0;
+	}
+
+	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+	if (!low_base) {
+		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
+		       (unsigned long)(low_size >> 20));
+		return -ENOMEM;
+	}
+
+	ret = memblock_reserve(low_base, low_size);
+	if (ret) {
+		pr_err("%s: Error reserving crashkernel low memblock.\n",
+				__func__);
+		return ret;
+	}
+
+	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
+		(unsigned long)(low_size >> 20),
+		(unsigned long)(low_base >> 20),
+		(unsigned long)(total_low_mem >> 20));
+
+	crashk_low_res.start = low_base;
+	crashk_low_res.end   = low_base + low_size - 1;
+#endif
+	return 0;
+}
+
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)
 {
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index c19c0dad1ebe..db66bbabfff3 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
 
-
-/* Location of the reserved area for the crash kernel */
-struct resource crashk_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-struct resource crashk_low_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-
 int kexec_should_crash(struct task_struct *p)
 {
 	/*
-- 
2.20.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v9 2/5] arm64: kdump: reserve crashkenel above 4G for crash dump kernel

[Chen Zhou]

Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

Suggested by James, just introduced crashkernel=X,low to arm64. As memtioned
above, if crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G, which is much simpler.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/arm64/kernel/setup.c |  8 +++++++-
 arch/arm64/mm/init.c      | 31 +++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 93b3844cf442..4dc51a2ac012 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -238,7 +238,13 @@ static void __init request_standard_resources(void)
 		    kernel_data.end <= res->end)
 			request_resource(res, &kernel_data);
 #ifdef CONFIG_KEXEC_CORE
-		/* Userspace will find "Crash kernel" region in /proc/iomem. */
+		/*
+		 * Userspace will find "Crash kernel" region in /proc/iomem.
+		 * Note: the low region is renamed as Crash kernel (low).
+		 */
+		if (crashk_low_res.end && crashk_low_res.start >= res->start &&
+				crashk_low_res.end <= res->end)
+			request_resource(res, &crashk_low_res);
 		if (crashk_res.end && crashk_res.start >= res->start &&
 		    crashk_res.end <= res->end)
 			request_resource(res, &crashk_res);
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 1e93cfc7c47a..ce7ced85f5fb 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -81,6 +81,7 @@ static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_base, crash_size;
 	int ret;
+	phys_addr_t crash_max = arm64_dma32_phys_limit;
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
@@ -88,12 +89,38 @@ static void __init reserve_crashkernel(void)
 	if (ret || !crash_size)
 		return;
 
+	ret = reserve_crashkernel_low();
+	if (!ret && crashk_low_res.end) {
+		/*
+		 * If crashkernel=X,low specified, there may be two regions,
+		 * we need to make some changes as follows:
+		 *
+		 * 1. rename the low region as "Crash kernel (low)"
+		 * In order to distinct from the high region and make no effect
+		 * to the use of existing kexec-tools, rename the low region as
+		 * "Crash kernel (low)".
+		 *
+		 * 2. change the upper bound for crash memory
+		 * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory.
+		 *
+		 * 3. mark the low region as "nomap"
+		 * The low region is intended to be used for crash dump kernel
+		 * devices, just mark the low region as "nomap" simply.
+		 */
+		const char *rename = "Crash kernel (low)";
+
+		crashk_low_res.name = rename;
+		crash_max = MEMBLOCK_ALLOC_ACCESSIBLE;
+		memblock_mark_nomap(crashk_low_res.start,
+				    resource_size(&crashk_low_res));
+	}
+
 	crash_size = PAGE_ALIGN(crash_size);
 
 	if (crash_base == 0) {
 		/* Current arm64 boot protocol requires 2MB alignment */
-		crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
-				crash_size, SZ_2M);
+		crash_base = memblock_find_in_range(0, crash_max, crash_size,
+				SZ_2M);
 		if (crash_base == 0) {
 			pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
 				crash_size);
-- 
2.20.1

[PATCH v9 2/5] arm64: kdump: reserve crashkenel above 4G for crash dump kernel

[Chen Zhou]

Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

Suggested by James, just introduced crashkernel=X,low to arm64. As memtioned
above, if crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G, which is much simpler.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/arm64/kernel/setup.c |  8 +++++++-
 arch/arm64/mm/init.c      | 31 +++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 93b3844cf442..4dc51a2ac012 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -238,7 +238,13 @@ static void __init request_standard_resources(void)
 		    kernel_data.end <= res->end)
 			request_resource(res, &kernel_data);
 #ifdef CONFIG_KEXEC_CORE
-		/* Userspace will find "Crash kernel" region in /proc/iomem. */
+		/*
+		 * Userspace will find "Crash kernel" region in /proc/iomem.
+		 * Note: the low region is renamed as Crash kernel (low).
+		 */
+		if (crashk_low_res.end && crashk_low_res.start >= res->start &&
+				crashk_low_res.end <= res->end)
+			request_resource(res, &crashk_low_res);
 		if (crashk_res.end && crashk_res.start >= res->start &&
 		    crashk_res.end <= res->end)
 			request_resource(res, &crashk_res);
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 1e93cfc7c47a..ce7ced85f5fb 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -81,6 +81,7 @@ static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_base, crash_size;
 	int ret;
+	phys_addr_t crash_max = arm64_dma32_phys_limit;
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
@@ -88,12 +89,38 @@ static void __init reserve_crashkernel(void)
 	if (ret || !crash_size)
 		return;
 
+	ret = reserve_crashkernel_low();
+	if (!ret && crashk_low_res.end) {
+		/*
+		 * If crashkernel=X,low specified, there may be two regions,
+		 * we need to make some changes as follows:
+		 *
+		 * 1. rename the low region as "Crash kernel (low)"
+		 * In order to distinct from the high region and make no effect
+		 * to the use of existing kexec-tools, rename the low region as
+		 * "Crash kernel (low)".
+		 *
+		 * 2. change the upper bound for crash memory
+		 * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory.
+		 *
+		 * 3. mark the low region as "nomap"
+		 * The low region is intended to be used for crash dump kernel
+		 * devices, just mark the low region as "nomap" simply.
+		 */
+		const char *rename = "Crash kernel (low)";
+
+		crashk_low_res.name = rename;
+		crash_max = MEMBLOCK_ALLOC_ACCESSIBLE;
+		memblock_mark_nomap(crashk_low_res.start,
+				    resource_size(&crashk_low_res));
+	}
+
 	crash_size = PAGE_ALIGN(crash_size);
 
 	if (crash_base == 0) {
 		/* Current arm64 boot protocol requires 2MB alignment */
-		crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
-				crash_size, SZ_2M);
+		crash_base = memblock_find_in_range(0, crash_max, crash_size,
+				SZ_2M);
 		if (crash_base == 0) {
 			pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
 				crash_size);
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v9 2/5] arm64: kdump: reserve crashkenel above 4G for crash dump kernel

[Chen Zhou]

Crashkernel=X tries to reserve memory for the crash dump kernel under
4G. If crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G.

Suggested by James, just introduced crashkernel=X,low to arm64. As memtioned
above, if crashkernel=X,low is specified simultaneously, reserve spcified
size low memory for crash kdump kernel devices firstly and then reserve
memory above 4G, which is much simpler.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/arm64/kernel/setup.c |  8 +++++++-
 arch/arm64/mm/init.c      | 31 +++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 93b3844cf442..4dc51a2ac012 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -238,7 +238,13 @@ static void __init request_standard_resources(void)
 		    kernel_data.end <= res->end)
 			request_resource(res, &kernel_data);
 #ifdef CONFIG_KEXEC_CORE
-		/* Userspace will find "Crash kernel" region in /proc/iomem. */
+		/*
+		 * Userspace will find "Crash kernel" region in /proc/iomem.
+		 * Note: the low region is renamed as Crash kernel (low).
+		 */
+		if (crashk_low_res.end && crashk_low_res.start >= res->start &&
+				crashk_low_res.end <= res->end)
+			request_resource(res, &crashk_low_res);
 		if (crashk_res.end && crashk_res.start >= res->start &&
 		    crashk_res.end <= res->end)
 			request_resource(res, &crashk_res);
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 1e93cfc7c47a..ce7ced85f5fb 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -81,6 +81,7 @@ static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_base, crash_size;
 	int ret;
+	phys_addr_t crash_max = arm64_dma32_phys_limit;
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
@@ -88,12 +89,38 @@ static void __init reserve_crashkernel(void)
 	if (ret || !crash_size)
 		return;
 
+	ret = reserve_crashkernel_low();
+	if (!ret && crashk_low_res.end) {
+		/*
+		 * If crashkernel=X,low specified, there may be two regions,
+		 * we need to make some changes as follows:
+		 *
+		 * 1. rename the low region as "Crash kernel (low)"
+		 * In order to distinct from the high region and make no effect
+		 * to the use of existing kexec-tools, rename the low region as
+		 * "Crash kernel (low)".
+		 *
+		 * 2. change the upper bound for crash memory
+		 * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory.
+		 *
+		 * 3. mark the low region as "nomap"
+		 * The low region is intended to be used for crash dump kernel
+		 * devices, just mark the low region as "nomap" simply.
+		 */
+		const char *rename = "Crash kernel (low)";
+
+		crashk_low_res.name = rename;
+		crash_max = MEMBLOCK_ALLOC_ACCESSIBLE;
+		memblock_mark_nomap(crashk_low_res.start,
+				    resource_size(&crashk_low_res));
+	}
+
 	crash_size = PAGE_ALIGN(crash_size);
 
 	if (crash_base == 0) {
 		/* Current arm64 boot protocol requires 2MB alignment */
-		crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
-				crash_size, SZ_2M);
+		crash_base = memblock_find_in_range(0, crash_max, crash_size,
+				SZ_2M);
 		if (crash_base == 0) {
 			pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
 				crash_size);
-- 
2.20.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v9 3/5] arm64: kdump: add memory for devices by DT property linux,usable-memory-range

[Chen Zhou]

If we want to reserve crashkernel above 4G, we could use parameters
"crashkernel=X crashkernel=Y,low", in this case, specified size low
memory is reserved for crash dump kernel devices and never mapped by
the first kernel. This memory range is advertised to crash dump kernel
via DT property under /chosen,
	linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>

We reused the DT property linux,usable-memory-range and made the low
memory region as the second range "BASE2 SIZE2", which keeps compatibility
with existing user-space and older kdump kernels.

Crash dump kernel reads this property at boot time and call memblock_add()
to add the low memory region after memblock_cap_memory_range() has been
called.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/arm64/mm/init.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index ce7ced85f5fb..f5b31e8f1f34 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -69,6 +69,15 @@ EXPORT_SYMBOL(vmemmap);
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 static phys_addr_t arm64_dma32_phys_limit __ro_after_init;
 
+/*
+ * The main usage of linux,usable-memory-range is for crash dump kernel.
+ * Originally, the number of usable-memory regions is one. Now crash dump
+ * kernel support at most two regions, low region and high region.
+ * To make compatibility with existing user-space and older kdump, the low
+ * region is always the last range of linux,usable-memory-range if exist.
+ */
+#define MAX_USABLE_RANGES	2
+
 #ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
@@ -272,9 +281,9 @@ early_param("mem", early_mem);
 static int __init early_init_dt_scan_usablemem(unsigned long node,
 		const char *uname, int depth, void *data)
 {
-	struct memblock_region *usablemem = data;
-	const __be32 *reg;
-	int len;
+	struct memblock_region *usable_rgns = data;
+	const __be32 *reg, *endp;
+	int len, nr = 0;
 
 	if (depth != 1 || strcmp(uname, "chosen") != 0)
 		return 0;
@@ -283,22 +292,36 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
 	if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
 		return 1;
 
-	usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
-	usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
+	endp = reg + (len / sizeof(__be32));
+	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
+		usable_rgns[nr].base = dt_mem_next_cell(dt_root_addr_cells, &reg);
+		usable_rgns[nr].size = dt_mem_next_cell(dt_root_size_cells, &reg);
+
+		if (++nr >= MAX_USABLE_RANGES)
+			break;
+	}
 
 	return 1;
 }
 
 static void __init fdt_enforce_memory_region(void)
 {
-	struct memblock_region reg = {
-		.size = 0,
+	struct memblock_region usable_rgns[MAX_USABLE_RANGES] = {
+		{ .size = 0 },
+		{ .size = 0 }
 	};
 
-	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
+	of_scan_flat_dt(early_init_dt_scan_usablemem, &usable_rgns);
 
-	if (reg.size)
-		memblock_cap_memory_range(reg.base, reg.size);
+	/*
+	 * The first range of usable-memory regions is for crash dump
+	 * kernel with only one region or for high region with two regions,
+	 * the second range is dedicated for low region if exist.
+	 */
+	if (usable_rgns[0].size)
+		memblock_cap_memory_range(usable_rgns[0].base, usable_rgns[0].size);
+	if (usable_rgns[1].size)
+		memblock_add(usable_rgns[1].base, usable_rgns[1].size);
 }
 
 void __init arm64_memblock_init(void)
-- 
2.20.1

[PATCH v9 3/5] arm64: kdump: add memory for devices by DT property linux, usable-memory-range

[Chen Zhou]

If we want to reserve crashkernel above 4G, we could use parameters
"crashkernel=X crashkernel=Y,low", in this case, specified size low
memory is reserved for crash dump kernel devices and never mapped by
the first kernel. This memory range is advertised to crash dump kernel
via DT property under /chosen,
	linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>

We reused the DT property linux,usable-memory-range and made the low
memory region as the second range "BASE2 SIZE2", which keeps compatibility
with existing user-space and older kdump kernels.

Crash dump kernel reads this property at boot time and call memblock_add()
to add the low memory region after memblock_cap_memory_range() has been
called.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/arm64/mm/init.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index ce7ced85f5fb..f5b31e8f1f34 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -69,6 +69,15 @@ EXPORT_SYMBOL(vmemmap);
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 static phys_addr_t arm64_dma32_phys_limit __ro_after_init;
 
+/*
+ * The main usage of linux,usable-memory-range is for crash dump kernel.
+ * Originally, the number of usable-memory regions is one. Now crash dump
+ * kernel support at most two regions, low region and high region.
+ * To make compatibility with existing user-space and older kdump, the low
+ * region is always the last range of linux,usable-memory-range if exist.
+ */
+#define MAX_USABLE_RANGES	2
+
 #ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
@@ -272,9 +281,9 @@ early_param("mem", early_mem);
 static int __init early_init_dt_scan_usablemem(unsigned long node,
 		const char *uname, int depth, void *data)
 {
-	struct memblock_region *usablemem = data;
-	const __be32 *reg;
-	int len;
+	struct memblock_region *usable_rgns = data;
+	const __be32 *reg, *endp;
+	int len, nr = 0;
 
 	if (depth != 1 || strcmp(uname, "chosen") != 0)
 		return 0;
@@ -283,22 +292,36 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
 	if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
 		return 1;
 
-	usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
-	usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
+	endp = reg + (len / sizeof(__be32));
+	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
+		usable_rgns[nr].base = dt_mem_next_cell(dt_root_addr_cells, &reg);
+		usable_rgns[nr].size = dt_mem_next_cell(dt_root_size_cells, &reg);
+
+		if (++nr >= MAX_USABLE_RANGES)
+			break;
+	}
 
 	return 1;
 }
 
 static void __init fdt_enforce_memory_region(void)
 {
-	struct memblock_region reg = {
-		.size = 0,
+	struct memblock_region usable_rgns[MAX_USABLE_RANGES] = {
+		{ .size = 0 },
+		{ .size = 0 }
 	};
 
-	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
+	of_scan_flat_dt(early_init_dt_scan_usablemem, &usable_rgns);
 
-	if (reg.size)
-		memblock_cap_memory_range(reg.base, reg.size);
+	/*
+	 * The first range of usable-memory regions is for crash dump
+	 * kernel with only one region or for high region with two regions,
+	 * the second range is dedicated for low region if exist.
+	 */
+	if (usable_rgns[0].size)
+		memblock_cap_memory_range(usable_rgns[0].base, usable_rgns[0].size);
+	if (usable_rgns[1].size)
+		memblock_add(usable_rgns[1].base, usable_rgns[1].size);
 }
 
 void __init arm64_memblock_init(void)
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v9 3/5] arm64: kdump: add memory for devices by DT property linux, usable-memory-range

[Chen Zhou]

If we want to reserve crashkernel above 4G, we could use parameters
"crashkernel=X crashkernel=Y,low", in this case, specified size low
memory is reserved for crash dump kernel devices and never mapped by
the first kernel. This memory range is advertised to crash dump kernel
via DT property under /chosen,
	linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>

We reused the DT property linux,usable-memory-range and made the low
memory region as the second range "BASE2 SIZE2", which keeps compatibility
with existing user-space and older kdump kernels.

Crash dump kernel reads this property at boot time and call memblock_add()
to add the low memory region after memblock_cap_memory_range() has been
called.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 arch/arm64/mm/init.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index ce7ced85f5fb..f5b31e8f1f34 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -69,6 +69,15 @@ EXPORT_SYMBOL(vmemmap);
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 static phys_addr_t arm64_dma32_phys_limit __ro_after_init;
 
+/*
+ * The main usage of linux,usable-memory-range is for crash dump kernel.
+ * Originally, the number of usable-memory regions is one. Now crash dump
+ * kernel support at most two regions, low region and high region.
+ * To make compatibility with existing user-space and older kdump, the low
+ * region is always the last range of linux,usable-memory-range if exist.
+ */
+#define MAX_USABLE_RANGES	2
+
 #ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
@@ -272,9 +281,9 @@ early_param("mem", early_mem);
 static int __init early_init_dt_scan_usablemem(unsigned long node,
 		const char *uname, int depth, void *data)
 {
-	struct memblock_region *usablemem = data;
-	const __be32 *reg;
-	int len;
+	struct memblock_region *usable_rgns = data;
+	const __be32 *reg, *endp;
+	int len, nr = 0;
 
 	if (depth != 1 || strcmp(uname, "chosen") != 0)
 		return 0;
@@ -283,22 +292,36 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
 	if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
 		return 1;
 
-	usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
-	usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
+	endp = reg + (len / sizeof(__be32));
+	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
+		usable_rgns[nr].base = dt_mem_next_cell(dt_root_addr_cells, &reg);
+		usable_rgns[nr].size = dt_mem_next_cell(dt_root_size_cells, &reg);
+
+		if (++nr >= MAX_USABLE_RANGES)
+			break;
+	}
 
 	return 1;
 }
 
 static void __init fdt_enforce_memory_region(void)
 {
-	struct memblock_region reg = {
-		.size = 0,
+	struct memblock_region usable_rgns[MAX_USABLE_RANGES] = {
+		{ .size = 0 },
+		{ .size = 0 }
 	};
 
-	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
+	of_scan_flat_dt(early_init_dt_scan_usablemem, &usable_rgns);
 
-	if (reg.size)
-		memblock_cap_memory_range(reg.base, reg.size);
+	/*
+	 * The first range of usable-memory regions is for crash dump
+	 * kernel with only one region or for high region with two regions,
+	 * the second range is dedicated for low region if exist.
+	 */
+	if (usable_rgns[0].size)
+		memblock_cap_memory_range(usable_rgns[0].base, usable_rgns[0].size);
+	if (usable_rgns[1].size)
+		memblock_add(usable_rgns[1].base, usable_rgns[1].size);
 }
 
 void __init arm64_memblock_init(void)
-- 
2.20.1


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[PATCH v9 4/5] arm64: kdump: fix kdump broken with ZONE_DMA reintroduced

[Chen Zhou]

commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32")
broken the arm64 kdump. If the memory reserved for crash dump kernel
falled in ZONE_DMA32, the devices in crash dump kernel need to use
ZONE_DMA will alloc fail.

This patch addressed the above issue based on "reserving crashkernel
above 4G". Originally, we reserve low memory below 4G, and now just need
to adjust memory limit to arm64_dma_phys_limit in reserve_crashkernel_low
if ZONE_DMA is enabled. That is, if there are devices need to use ZONE_DMA
in crash dump kernel, it is a good choice to use parameters
"crashkernel=X crashkernel=Y,low".

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
 kernel/crash_core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index a7580d291c37..e8ecbbc761a3 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -320,6 +320,7 @@ int __init reserve_crashkernel_low(void)
 	unsigned long long base, low_base = 0, low_size = 0;
 	unsigned long total_low_mem;
 	int ret;
+	phys_addr_t crash_max = 1ULL << 32;
 
 	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
 
@@ -352,7 +353,11 @@ int __init reserve_crashkernel_low(void)
 			return 0;
 	}
 
-	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+#ifdef CONFIG_ARM64
+	if (IS_ENABLED(CONFIG_ZONE_DMA))
+		crash_max = arm64_dma_phys_limit;
+#endif
+	low_base = memblock_find_in_range(0, crash_max, low_size, CRASH_ALIGN);
 	if (!low_base) {
 		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
 		       (unsigned long)(low_size >> 20));
-- 
2.20.1

[PATCH v9 4/5] arm64: kdump: fix kdump broken with ZONE_DMA reintroduced

[Chen Zhou]

commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32")
broken the arm64 kdump. If the memory reserved for crash dump kernel
falled in ZONE_DMA32, the devices in crash dump kernel need to use
ZONE_DMA will alloc fail.

This patch addressed the above issue based on "reserving crashkernel
above 4G". Originally, we reserve low memory below 4G, and now just need
to adjust memory limit to arm64_dma_phys_limit in reserve_crashkernel_low
if ZONE_DMA is enabled. That is, if there are devices need to use ZONE_DMA
in crash dump kernel, it is a good choice to use parameters
"crashkernel=X crashkernel=Y,low".

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
 kernel/crash_core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index a7580d291c37..e8ecbbc761a3 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -320,6 +320,7 @@ int __init reserve_crashkernel_low(void)
 	unsigned long long base, low_base = 0, low_size = 0;
 	unsigned long total_low_mem;
 	int ret;
+	phys_addr_t crash_max = 1ULL << 32;
 
 	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
 
@@ -352,7 +353,11 @@ int __init reserve_crashkernel_low(void)
 			return 0;
 	}
 
-	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+#ifdef CONFIG_ARM64
+	if (IS_ENABLED(CONFIG_ZONE_DMA))
+		crash_max = arm64_dma_phys_limit;
+#endif
+	low_base = memblock_find_in_range(0, crash_max, low_size, CRASH_ALIGN);
 	if (!low_base) {
 		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
 		       (unsigned long)(low_size >> 20));
-- 
2.20.1


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[PATCH v9 4/5] arm64: kdump: fix kdump broken with ZONE_DMA reintroduced

[Chen Zhou]

commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32")
broken the arm64 kdump. If the memory reserved for crash dump kernel
falled in ZONE_DMA32, the devices in crash dump kernel need to use
ZONE_DMA will alloc fail.

This patch addressed the above issue based on "reserving crashkernel
above 4G". Originally, we reserve low memory below 4G, and now just need
to adjust memory limit to arm64_dma_phys_limit in reserve_crashkernel_low
if ZONE_DMA is enabled. That is, if there are devices need to use ZONE_DMA
in crash dump kernel, it is a good choice to use parameters
"crashkernel=X crashkernel=Y,low".

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
 kernel/crash_core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index a7580d291c37..e8ecbbc761a3 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -320,6 +320,7 @@ int __init reserve_crashkernel_low(void)
 	unsigned long long base, low_base = 0, low_size = 0;
 	unsigned long total_low_mem;
 	int ret;
+	phys_addr_t crash_max = 1ULL << 32;
 
 	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
 
@@ -352,7 +353,11 @@ int __init reserve_crashkernel_low(void)
 			return 0;
 	}
 
-	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+#ifdef CONFIG_ARM64
+	if (IS_ENABLED(CONFIG_ZONE_DMA))
+		crash_max = arm64_dma_phys_limit;
+#endif
+	low_base = memblock_find_in_range(0, crash_max, low_size, CRASH_ALIGN);
 	if (!low_base) {
 		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
 		       (unsigned long)(low_size >> 20));
-- 
2.20.1


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[PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[Chen Zhou]

Now we support crashkernel=X,[low] on arm64, update the Documentation.
We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
memory above 4G.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
 Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 2da65fef2a1c..6ba294d425c9 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -299,7 +299,13 @@ Boot into System Kernel
    "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
    starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
 
-   On x86 and x86_64, use "crashkernel=64M@16M".
+   On x86 use "crashkernel=64M@16M".
+
+   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
+   fall back to reserve region above 4G when '@offset' hasn't been specified.
+   We can also use "crashkernel=X,high" to select a region above 4G, which
+   also tries to allocate at least 256M below 4G automatically and
+   "crashkernel=Y,low" can be used to allocate specified size low memory.
 
    On ppc64, use "crashkernel=128M@32M".
 
@@ -316,8 +322,11 @@ Boot into System Kernel
    kernel will automatically locate the crash kernel image within the
    first 512MB of RAM if X is not given.
 
-   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
+   On arm64, use "crashkernel=Y[@X]". Note that the start address of
    the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+   If crashkernel=Z,low is specified simultaneously, reserve spcified size
+   low memory for crash kdump kernel devices firstly and then reserve memory
+   above 4G.
 
 Load the Dump-capture Kernel
 ============================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb95fad81c79..335431a351c0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -722,6 +722,9 @@
 			[KNL, x86_64] select a region under 4G first, and
 			fall back to reserve region above 4G when '@offset'
 			hasn't been specified.
+			[KNL, arm64] If crashkernel=X,low is specified, reserve
+			spcified size low memory for crash kdump kernel devices
+			firstly, and then reserve memory above 4G.
 			See Documentation/admin-guide/kdump/kdump.rst for further details.
 
 	crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -746,13 +749,23 @@
 			requires at least 64M+32K low memory, also enough extra
 			low memory is needed to make sure DMA buffers for 32-bit
 			devices won't run out. Kernel would try to allocate at
-			at least 256M below 4G automatically.
+			least 256M below 4G automatically.
 			This one let user to specify own low range under 4G
 			for second kernel instead.
 			0: to disable low allocation.
 			It will be ignored when crashkernel=X,high is not used
 			or memory reserved is below 4G.
-
+			[KNL, arm64] range under 4G.
+			This one let user to specify own low range under 4G
+			for crash dump kernel instead.
+			Different with x86_64, kernel allocates specified size
+			physical memory region only when this parameter is specified
+			instead of trying to allocate at least 256M below 4G
+			automatically.
+			This parameter is used along with crashkernel=X when we
+			want to reserve crashkernel above 4G. If there are devices
+			need to use ZONE_DMA in crash dump kernel, it is also
+			a good choice.
 	cryptomgr.notests
 			[KNL] Disable crypto self-tests
 
-- 
2.20.1

[PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[Chen Zhou]

Now we support crashkernel=X,[low] on arm64, update the Documentation.
We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
memory above 4G.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
 Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 2da65fef2a1c..6ba294d425c9 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -299,7 +299,13 @@ Boot into System Kernel
    "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
    starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
 
-   On x86 and x86_64, use "crashkernel=64M@16M".
+   On x86 use "crashkernel=64M@16M".
+
+   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
+   fall back to reserve region above 4G when '@offset' hasn't been specified.
+   We can also use "crashkernel=X,high" to select a region above 4G, which
+   also tries to allocate at least 256M below 4G automatically and
+   "crashkernel=Y,low" can be used to allocate specified size low memory.
 
    On ppc64, use "crashkernel=128M@32M".
 
@@ -316,8 +322,11 @@ Boot into System Kernel
    kernel will automatically locate the crash kernel image within the
    first 512MB of RAM if X is not given.
 
-   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
+   On arm64, use "crashkernel=Y[@X]". Note that the start address of
    the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+   If crashkernel=Z,low is specified simultaneously, reserve spcified size
+   low memory for crash kdump kernel devices firstly and then reserve memory
+   above 4G.
 
 Load the Dump-capture Kernel
 ============================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb95fad81c79..335431a351c0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -722,6 +722,9 @@
 			[KNL, x86_64] select a region under 4G first, and
 			fall back to reserve region above 4G when '@offset'
 			hasn't been specified.
+			[KNL, arm64] If crashkernel=X,low is specified, reserve
+			spcified size low memory for crash kdump kernel devices
+			firstly, and then reserve memory above 4G.
 			See Documentation/admin-guide/kdump/kdump.rst for further details.
 
 	crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -746,13 +749,23 @@
 			requires at least 64M+32K low memory, also enough extra
 			low memory is needed to make sure DMA buffers for 32-bit
 			devices won't run out. Kernel would try to allocate at
-			at least 256M below 4G automatically.
+			least 256M below 4G automatically.
 			This one let user to specify own low range under 4G
 			for second kernel instead.
 			0: to disable low allocation.
 			It will be ignored when crashkernel=X,high is not used
 			or memory reserved is below 4G.
-
+			[KNL, arm64] range under 4G.
+			This one let user to specify own low range under 4G
+			for crash dump kernel instead.
+			Different with x86_64, kernel allocates specified size
+			physical memory region only when this parameter is specified
+			instead of trying to allocate at least 256M below 4G
+			automatically.
+			This parameter is used along with crashkernel=X when we
+			want to reserve crashkernel above 4G. If there are devices
+			need to use ZONE_DMA in crash dump kernel, it is also
+			a good choice.
 	cryptomgr.notests
 			[KNL] Disable crypto self-tests
 
-- 
2.20.1


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[PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[Chen Zhou]

Now we support crashkernel=X,[low] on arm64, update the Documentation.
We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
memory above 4G.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
---
 Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
 Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 2da65fef2a1c..6ba294d425c9 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -299,7 +299,13 @@ Boot into System Kernel
    "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
    starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
 
-   On x86 and x86_64, use "crashkernel=64M@16M".
+   On x86 use "crashkernel=64M@16M".
+
+   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
+   fall back to reserve region above 4G when '@offset' hasn't been specified.
+   We can also use "crashkernel=X,high" to select a region above 4G, which
+   also tries to allocate at least 256M below 4G automatically and
+   "crashkernel=Y,low" can be used to allocate specified size low memory.
 
    On ppc64, use "crashkernel=128M@32M".
 
@@ -316,8 +322,11 @@ Boot into System Kernel
    kernel will automatically locate the crash kernel image within the
    first 512MB of RAM if X is not given.
 
-   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
+   On arm64, use "crashkernel=Y[@X]". Note that the start address of
    the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+   If crashkernel=Z,low is specified simultaneously, reserve spcified size
+   low memory for crash kdump kernel devices firstly and then reserve memory
+   above 4G.
 
 Load the Dump-capture Kernel
 ============================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb95fad81c79..335431a351c0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -722,6 +722,9 @@
 			[KNL, x86_64] select a region under 4G first, and
 			fall back to reserve region above 4G when '@offset'
 			hasn't been specified.
+			[KNL, arm64] If crashkernel=X,low is specified, reserve
+			spcified size low memory for crash kdump kernel devices
+			firstly, and then reserve memory above 4G.
 			See Documentation/admin-guide/kdump/kdump.rst for further details.
 
 	crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -746,13 +749,23 @@
 			requires at least 64M+32K low memory, also enough extra
 			low memory is needed to make sure DMA buffers for 32-bit
 			devices won't run out. Kernel would try to allocate at
-			at least 256M below 4G automatically.
+			least 256M below 4G automatically.
 			This one let user to specify own low range under 4G
 			for second kernel instead.
 			0: to disable low allocation.
 			It will be ignored when crashkernel=X,high is not used
 			or memory reserved is below 4G.
-
+			[KNL, arm64] range under 4G.
+			This one let user to specify own low range under 4G
+			for crash dump kernel instead.
+			Different with x86_64, kernel allocates specified size
+			physical memory region only when this parameter is specified
+			instead of trying to allocate at least 256M below 4G
+			automatically.
+			This parameter is used along with crashkernel=X when we
+			want to reserve crashkernel above 4G. If there are devices
+			need to use ZONE_DMA in crash dump kernel, it is also
+			a good choice.
 	cryptomgr.notests
 			[KNL] Disable crypto self-tests
 
-- 
2.20.1


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Re: [PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[John Donnelly]

Hi , 

> On Jun 28, 2020, at 3:34 AM, Chen Zhou <chenzhou10@huawei.com> wrote:
> 
> This patch series enable reserving crashkernel above 4G in arm64.
> 
> There are following issues in arm64 kdump:
> 1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
> when there is no enough low memory.
> 2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
> in this case, if swiotlb or DMA buffers are required, crash dump kernel
> will boot failure because there is no low memory available for allocation.
> 3. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken
> the arm64 kdump. If the memory reserved for crash dump kernel falled in
> ZONE_DMA32, the devices in crash dump kernel need to use ZONE_DMA will alloc
> fail.
> 
> To solve these issues, introduce crashkernel=X,low to reserve specified
> size low memory.
> Crashkernel=X tries to reserve memory for the crash dump kernel under
> 4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
> size low memory for crash kdump kernel devices firstly and then reserve
> memory above 4G.
> 
> When crashkernel is reserved above 4G in memory and crashkernel=X,low
> is specified simultaneously, kernel should reserve specified size low memory
> for crash dump kernel devices. So there may be two crash kernel regions, one
> is below 4G, the other is above 4G.
> In order to distinct from the high region and make no effect to the use of
> kexec-tools, rename the low region as "Crash kernel (low)", and pass the
> low region by reusing DT property "linux,usable-memory-range". We made the low
> memory region as the last range of "linux,usable-memory-range" to keep
> compatibility with existing user-space and older kdump kernels.
> 
> Besides, we need to modify kexec-tools:
> arm64: support more than one crash kernel regions(see [1])
> 
> Another update is document about DT property 'linux,usable-memory-range':
> schemas: update 'linux,usable-memory-range' node schema(see [2])
> 
> The previous changes and discussions can be retrieved from:
> 
> Changes since [v8]
> - Reuse DT property "linux,usable-memory-range".
> Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low
> memory region.
> - Fix kdump broken with ZONE_DMA reintroduced.
> - Update chosen schema.

  
  Nice job Chen, 

  Does this need a Ack-by from the Raspberry maintainers on this ZONE_DMA fix  ?

  This activity has been going on for over a year now.  Can we please get this finalized and merged ?
 
 Thank you,
 John.



> 
> Changes since [v7]
> - Move x86 CRASH_ALIGN to 2M
> Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M.
> - Update Documentation/devicetree/bindings/chosen.txt.
> Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt
> suggested by Arnd.
> - Add Tested-by from Jhon and pk.
> 
> Changes since [v6]
> - Fix build errors reported by kbuild test robot.
> 
> Changes since [v5]
> - Move reserve_crashkernel_low() into kernel/crash_core.c.
> - Delete crashkernel=X,high.
> - Modify crashkernel=X,low.
> If crashkernel=X,low is specified simultaneously, reserve spcified size low
> memory for crash kdump kernel devices firstly and then reserve memory above 4G.
> In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
> pass to crash dump kernel by DT property "linux,low-memory-range".
> - Update Documentation/admin-guide/kdump/kdump.rst.
> 
> Changes since [v4]
> - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.
> 
> Changes since [v3]
> - Add memblock_cap_memory_ranges back for multiple ranges.
> - Fix some compiling warnings.
> 
> Changes since [v2]
> - Split patch "arm64: kdump: support reserving crashkernel above 4G" as
> two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
> patch.
> 
> Changes since [v1]:
> - Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
> - Remove memblock_cap_memory_ranges() i added in v1 and implement that
> in fdt_enforce_memory_region().
> There are at most two crash kernel regions, for two crash kernel regions
> case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
> and then remove the memory range in the middle.
> 
> [1]: https://urldefense.com/v3/__http://lists.infradead.org/pipermail/kexec/2020-June/020737.html__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw-1A43Ss$ 
> [2]: https://urldefense.com/v3/__https://github.com/robherring/dt-schema/pull/19__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw9xTB8yT$  
> [v1]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/2/1174__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw2EAOIhM$ 
> [v2]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/86__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwx3ILnLL$ 
> [v3]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/306__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw5YJeYoP$ 
> [v4]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/15/273__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwxbrySTW$ 
> [v5]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/5/6/1360__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwzGOGcMs$ 
> [v6]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/8/30/142__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw70P0bKy$ 
> [v7]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/12/23/411__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw29m6Wrh$ 
> [v8]: https://urldefense.com/v3/__https://lkml.org/lkml/2020/5/21/213__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw-jGzScF$ 
> 
> Chen Zhou (5):
>  x86: kdump: move reserve_crashkernel_low() into crash_core.c
>  arm64: kdump: reserve crashkenel above 4G for crash dump kernel
>  arm64: kdump: add memory for devices by DT property
>    linux,usable-memory-range
>  arm64: kdump: fix kdump broken with ZONE_DMA reintroduced
>  kdump: update Documentation about crashkernel on arm64
> 
> Documentation/admin-guide/kdump/kdump.rst     | 13 ++-
> .../admin-guide/kernel-parameters.txt         | 17 +++-
> arch/arm64/kernel/setup.c                     |  8 +-
> arch/arm64/mm/init.c                          | 74 ++++++++++++---
> arch/x86/kernel/setup.c                       | 66 ++------------
> include/linux/crash_core.h                    |  3 +
> include/linux/kexec.h                         |  2 -
> kernel/crash_core.c                           | 90 +++++++++++++++++++
> kernel/kexec_core.c                           | 17 ----
> 9 files changed, 196 insertions(+), 94 deletions(-)
> 
> -- 
> 2.20.1
> 

Re: [PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[John Donnelly]

Hi , 

> On Jun 28, 2020, at 3:34 AM, Chen Zhou <chenzhou10@huawei.com> wrote:
> 
> This patch series enable reserving crashkernel above 4G in arm64.
> 
> There are following issues in arm64 kdump:
> 1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
> when there is no enough low memory.
> 2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
> in this case, if swiotlb or DMA buffers are required, crash dump kernel
> will boot failure because there is no low memory available for allocation.
> 3. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken
> the arm64 kdump. If the memory reserved for crash dump kernel falled in
> ZONE_DMA32, the devices in crash dump kernel need to use ZONE_DMA will alloc
> fail.
> 
> To solve these issues, introduce crashkernel=X,low to reserve specified
> size low memory.
> Crashkernel=X tries to reserve memory for the crash dump kernel under
> 4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
> size low memory for crash kdump kernel devices firstly and then reserve
> memory above 4G.
> 
> When crashkernel is reserved above 4G in memory and crashkernel=X,low
> is specified simultaneously, kernel should reserve specified size low memory
> for crash dump kernel devices. So there may be two crash kernel regions, one
> is below 4G, the other is above 4G.
> In order to distinct from the high region and make no effect to the use of
> kexec-tools, rename the low region as "Crash kernel (low)", and pass the
> low region by reusing DT property "linux,usable-memory-range". We made the low
> memory region as the last range of "linux,usable-memory-range" to keep
> compatibility with existing user-space and older kdump kernels.
> 
> Besides, we need to modify kexec-tools:
> arm64: support more than one crash kernel regions(see [1])
> 
> Another update is document about DT property 'linux,usable-memory-range':
> schemas: update 'linux,usable-memory-range' node schema(see [2])
> 
> The previous changes and discussions can be retrieved from:
> 
> Changes since [v8]
> - Reuse DT property "linux,usable-memory-range".
> Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low
> memory region.
> - Fix kdump broken with ZONE_DMA reintroduced.
> - Update chosen schema.

  
  Nice job Chen, 

  Does this need a Ack-by from the Raspberry maintainers on this ZONE_DMA fix  ?

  This activity has been going on for over a year now.  Can we please get this finalized and merged ?
 
 Thank you,
 John.



> 
> Changes since [v7]
> - Move x86 CRASH_ALIGN to 2M
> Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M.
> - Update Documentation/devicetree/bindings/chosen.txt.
> Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt
> suggested by Arnd.
> - Add Tested-by from Jhon and pk.
> 
> Changes since [v6]
> - Fix build errors reported by kbuild test robot.
> 
> Changes since [v5]
> - Move reserve_crashkernel_low() into kernel/crash_core.c.
> - Delete crashkernel=X,high.
> - Modify crashkernel=X,low.
> If crashkernel=X,low is specified simultaneously, reserve spcified size low
> memory for crash kdump kernel devices firstly and then reserve memory above 4G.
> In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
> pass to crash dump kernel by DT property "linux,low-memory-range".
> - Update Documentation/admin-guide/kdump/kdump.rst.
> 
> Changes since [v4]
> - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.
> 
> Changes since [v3]
> - Add memblock_cap_memory_ranges back for multiple ranges.
> - Fix some compiling warnings.
> 
> Changes since [v2]
> - Split patch "arm64: kdump: support reserving crashkernel above 4G" as
> two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
> patch.
> 
> Changes since [v1]:
> - Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
> - Remove memblock_cap_memory_ranges() i added in v1 and implement that
> in fdt_enforce_memory_region().
> There are at most two crash kernel regions, for two crash kernel regions
> case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
> and then remove the memory range in the middle.
> 
> [1]: https://urldefense.com/v3/__http://lists.infradead.org/pipermail/kexec/2020-June/020737.html__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw-1A43Ss$ 
> [2]: https://urldefense.com/v3/__https://github.com/robherring/dt-schema/pull/19__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw9xTB8yT$  
> [v1]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/2/1174__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw2EAOIhM$ 
> [v2]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/86__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwx3ILnLL$ 
> [v3]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/306__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw5YJeYoP$ 
> [v4]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/15/273__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwxbrySTW$ 
> [v5]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/5/6/1360__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwzGOGcMs$ 
> [v6]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/8/30/142__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw70P0bKy$ 
> [v7]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/12/23/411__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw29m6Wrh$ 
> [v8]: https://urldefense.com/v3/__https://lkml.org/lkml/2020/5/21/213__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw-jGzScF$ 
> 
> Chen Zhou (5):
>  x86: kdump: move reserve_crashkernel_low() into crash_core.c
>  arm64: kdump: reserve crashkenel above 4G for crash dump kernel
>  arm64: kdump: add memory for devices by DT property
>    linux,usable-memory-range
>  arm64: kdump: fix kdump broken with ZONE_DMA reintroduced
>  kdump: update Documentation about crashkernel on arm64
> 
> Documentation/admin-guide/kdump/kdump.rst     | 13 ++-
> .../admin-guide/kernel-parameters.txt         | 17 +++-
> arch/arm64/kernel/setup.c                     |  8 +-
> arch/arm64/mm/init.c                          | 74 ++++++++++++---
> arch/x86/kernel/setup.c                       | 66 ++------------
> include/linux/crash_core.h                    |  3 +
> include/linux/kexec.h                         |  2 -
> kernel/crash_core.c                           | 90 +++++++++++++++++++
> kernel/kexec_core.c                           | 17 ----
> 9 files changed, 196 insertions(+), 94 deletions(-)
> 
> -- 
> 2.20.1
> 


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v9 0/5] support reserving crashkernel above 4G on arm64 kdump

[John Donnelly]

Hi , 

> On Jun 28, 2020, at 3:34 AM, Chen Zhou <chenzhou10@huawei.com> wrote:
> 
> This patch series enable reserving crashkernel above 4G in arm64.
> 
> There are following issues in arm64 kdump:
> 1. We use crashkernel=X to reserve crashkernel below 4G, which will fail
> when there is no enough low memory.
> 2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G,
> in this case, if swiotlb or DMA buffers are required, crash dump kernel
> will boot failure because there is no low memory available for allocation.
> 3. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken
> the arm64 kdump. If the memory reserved for crash dump kernel falled in
> ZONE_DMA32, the devices in crash dump kernel need to use ZONE_DMA will alloc
> fail.
> 
> To solve these issues, introduce crashkernel=X,low to reserve specified
> size low memory.
> Crashkernel=X tries to reserve memory for the crash dump kernel under
> 4G. If crashkernel=Y,low is specified simultaneously, reserve spcified
> size low memory for crash kdump kernel devices firstly and then reserve
> memory above 4G.
> 
> When crashkernel is reserved above 4G in memory and crashkernel=X,low
> is specified simultaneously, kernel should reserve specified size low memory
> for crash dump kernel devices. So there may be two crash kernel regions, one
> is below 4G, the other is above 4G.
> In order to distinct from the high region and make no effect to the use of
> kexec-tools, rename the low region as "Crash kernel (low)", and pass the
> low region by reusing DT property "linux,usable-memory-range". We made the low
> memory region as the last range of "linux,usable-memory-range" to keep
> compatibility with existing user-space and older kdump kernels.
> 
> Besides, we need to modify kexec-tools:
> arm64: support more than one crash kernel regions(see [1])
> 
> Another update is document about DT property 'linux,usable-memory-range':
> schemas: update 'linux,usable-memory-range' node schema(see [2])
> 
> The previous changes and discussions can be retrieved from:
> 
> Changes since [v8]
> - Reuse DT property "linux,usable-memory-range".
> Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low
> memory region.
> - Fix kdump broken with ZONE_DMA reintroduced.
> - Update chosen schema.

  
  Nice job Chen, 

  Does this need a Ack-by from the Raspberry maintainers on this ZONE_DMA fix  ?

  This activity has been going on for over a year now.  Can we please get this finalized and merged ?
 
 Thank you,
 John.



> 
> Changes since [v7]
> - Move x86 CRASH_ALIGN to 2M
> Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M.
> - Update Documentation/devicetree/bindings/chosen.txt.
> Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt
> suggested by Arnd.
> - Add Tested-by from Jhon and pk.
> 
> Changes since [v6]
> - Fix build errors reported by kbuild test robot.
> 
> Changes since [v5]
> - Move reserve_crashkernel_low() into kernel/crash_core.c.
> - Delete crashkernel=X,high.
> - Modify crashkernel=X,low.
> If crashkernel=X,low is specified simultaneously, reserve spcified size low
> memory for crash kdump kernel devices firstly and then reserve memory above 4G.
> In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then
> pass to crash dump kernel by DT property "linux,low-memory-range".
> - Update Documentation/admin-guide/kdump/kdump.rst.
> 
> Changes since [v4]
> - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike.
> 
> Changes since [v3]
> - Add memblock_cap_memory_ranges back for multiple ranges.
> - Fix some compiling warnings.
> 
> Changes since [v2]
> - Split patch "arm64: kdump: support reserving crashkernel above 4G" as
> two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate
> patch.
> 
> Changes since [v1]:
> - Move common reserve_crashkernel_low() code into kernel/kexec_core.c.
> - Remove memblock_cap_memory_ranges() i added in v1 and implement that
> in fdt_enforce_memory_region().
> There are at most two crash kernel regions, for two crash kernel regions
> case, we cap the memory range [min(regs[*].start), max(regs[*].end)]
> and then remove the memory range in the middle.
> 
> [1]: https://urldefense.com/v3/__http://lists.infradead.org/pipermail/kexec/2020-June/020737.html__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw-1A43Ss$ 
> [2]: https://urldefense.com/v3/__https://github.com/robherring/dt-schema/pull/19__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw9xTB8yT$  
> [v1]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/2/1174__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw2EAOIhM$ 
> [v2]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/86__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwx3ILnLL$ 
> [v3]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/306__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw5YJeYoP$ 
> [v4]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/15/273__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwxbrySTW$ 
> [v5]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/5/6/1360__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbwzGOGcMs$ 
> [v6]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/8/30/142__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw70P0bKy$ 
> [v7]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/12/23/411__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw29m6Wrh$ 
> [v8]: https://urldefense.com/v3/__https://lkml.org/lkml/2020/5/21/213__;!!GqivPVa7Brio!OnPQrQrzeDmjwp6OTFe3rN1ddb-AUny-Wq5vlaMfxI3rSentYYQy-2H91dqbw-jGzScF$ 
> 
> Chen Zhou (5):
>  x86: kdump: move reserve_crashkernel_low() into crash_core.c
>  arm64: kdump: reserve crashkenel above 4G for crash dump kernel
>  arm64: kdump: add memory for devices by DT property
>    linux,usable-memory-range
>  arm64: kdump: fix kdump broken with ZONE_DMA reintroduced
>  kdump: update Documentation about crashkernel on arm64
> 
> Documentation/admin-guide/kdump/kdump.rst     | 13 ++-
> .../admin-guide/kernel-parameters.txt         | 17 +++-
> arch/arm64/kernel/setup.c                     |  8 +-
> arch/arm64/mm/init.c                          | 74 ++++++++++++---
> arch/x86/kernel/setup.c                       | 66 ++------------
> include/linux/crash_core.h                    |  3 +
> include/linux/kexec.h                         |  2 -
> kernel/crash_core.c                           | 90 +++++++++++++++++++
> kernel/kexec_core.c                           | 17 ----
> 9 files changed, 196 insertions(+), 94 deletions(-)
> 
> -- 
> 2.20.1
> 


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH v9 1/5] x86: kdump: move reserve_crashkernel_low() into crash_core.c

[Dave Young]

On 06/28/20 at 04:34pm, Chen Zhou wrote:
> In preparation for supporting reserve_crashkernel_low in arm64 as
> x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.
> 
> BTW, move x86_64 CRASH_ALIGN to 2M suggested by Dave. CONFIG_PHYSICAL_ALIGN
> can be selected from 2M to 16M, move to the same as arm64.
> 
> Note, in arm64, we reserve low memory if and only if crashkernel=X,low
> is specified. Different with x86_64, don't set low memory automatically.
> 
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> ---
>  arch/x86/kernel/setup.c    | 66 ++++-------------------------
>  include/linux/crash_core.h |  3 ++
>  include/linux/kexec.h      |  2 -
>  kernel/crash_core.c        | 85 ++++++++++++++++++++++++++++++++++++++
>  kernel/kexec_core.c        | 17 --------
>  5 files changed, 96 insertions(+), 77 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index a3767e74c758..33db99ae3035 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -401,8 +401,8 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  
>  #ifdef CONFIG_KEXEC_CORE
>  
> -/* 16M alignment for crash kernel regions */
> -#define CRASH_ALIGN		SZ_16M
> +/* 2M alignment for crash kernel regions */
> +#define CRASH_ALIGN		SZ_2M
>  
>  /*
>   * Keep the crash kernel below this limit.
> @@ -425,59 +425,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  # define CRASH_ADDR_HIGH_MAX	SZ_64T
>  #endif
>  
> -static int __init reserve_crashkernel_low(void)
> -{
> -#ifdef CONFIG_X86_64
> -	unsigned long long base, low_base = 0, low_size = 0;
> -	unsigned long total_low_mem;
> -	int ret;
> -
> -	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> -
> -	/* crashkernel=Y,low */
> -	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
> -	if (ret) {
> -		/*
> -		 * two parts from kernel/dma/swiotlb.c:
> -		 * -swiotlb size: user-specified with swiotlb= or default.
> -		 *
> -		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> -		 * to 8M for other buffers that may need to stay low too. Also
> -		 * make sure we allocate enough extra low memory so that we
> -		 * don't run out of DMA buffers for 32-bit devices.
> -		 */
> -		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> -	} else {
> -		/* passed with crashkernel=0,low ? */
> -		if (!low_size)
> -			return 0;
> -	}
> -
> -	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> -	if (!low_base) {
> -		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> -		       (unsigned long)(low_size >> 20));
> -		return -ENOMEM;
> -	}
> -
> -	ret = memblock_reserve(low_base, low_size);
> -	if (ret) {
> -		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
> -		return ret;
> -	}
> -
> -	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> -		(unsigned long)(low_size >> 20),
> -		(unsigned long)(low_base >> 20),
> -		(unsigned long)(total_low_mem >> 20));
> -
> -	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;
> -}
> -
>  static void __init reserve_crashkernel(void)
>  {
>  	unsigned long long crash_size, crash_base, total_mem;
> @@ -541,9 +488,12 @@ static void __init reserve_crashkernel(void)
>  		return;
>  	}
>  
> -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> -		memblock_free(crash_base, crash_size);
> -		return;
> +	if (crash_base >= (1ULL << 32)) {
> +		if (reserve_crashkernel_low()) {
> +			memblock_free(crash_base, crash_size);
> +			return;
> +		}
> +		insert_resource(&iomem_resource, &crashk_low_res);
>  	}
>  
>  	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 525510a9f965..4df8c0bff03e 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -63,6 +63,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
>  extern unsigned char *vmcoreinfo_data;
>  extern size_t vmcoreinfo_size;
>  extern u32 *vmcoreinfo_note;
> +extern struct resource crashk_res;
> +extern struct resource crashk_low_res;
>  
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
> @@ -74,5 +76,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
>  int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
> +int __init reserve_crashkernel_low(void);
>  
>  #endif /* LINUX_CRASH_CORE_H */
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index ea67910ae6b7..a460afdbab0f 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -330,8 +330,6 @@ extern int kexec_load_disabled;
>  
>  /* Location of a reserved region to hold the crash kernel.
>   */
> -extern struct resource crashk_res;
> -extern struct resource crashk_low_res;
>  extern note_buf_t __percpu *crash_notes;
>  
>  /* flag to track if kexec reboot is in progress */
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 9f1557b98468..a7580d291c37 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -7,6 +7,8 @@
>  #include <linux/crash_core.h>
>  #include <linux/utsname.h>
>  #include <linux/vmalloc.h>
> +#include <linux/memblock.h>
> +#include <linux/swiotlb.h>
>  
>  #include <asm/page.h>
>  #include <asm/sections.h>
> @@ -19,6 +21,22 @@ u32 *vmcoreinfo_note;
>  /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
>  static unsigned char *vmcoreinfo_data_safecopy;
>  
> +/* Location of the reserved area for the crash kernel */
> +struct resource crashk_res = {
> +	.name  = "Crash kernel",
> +	.start = 0,
> +	.end   = 0,
> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> +	.desc  = IORES_DESC_CRASH_KERNEL
> +};
> +struct resource crashk_low_res = {
> +	.name  = "Crash kernel",
> +	.start = 0,
> +	.end   = 0,
> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> +	.desc  = IORES_DESC_CRASH_KERNEL
> +};
> +
>  /*
>   * parsing the "crashkernel" commandline
>   *
> @@ -292,6 +310,73 @@ int __init parse_crashkernel_low(char *cmdline,
>  				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
>  }
>  
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> +#define CRASH_ALIGN		SZ_2M
> +#endif
> +
> +int __init reserve_crashkernel_low(void)
> +{
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> +	unsigned long long base, low_base = 0, low_size = 0;
> +	unsigned long total_low_mem;
> +	int ret;
> +
> +	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> +
> +	/* crashkernel=Y,low */
> +	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
> +			&base);
> +	if (ret) {
> +#ifdef CONFIG_X86_64
> +		/*
> +		 * two parts from lib/swiotlb.c:
> +		 * -swiotlb size: user-specified with swiotlb= or default.
> +		 *
> +		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> +		 * to 8M for other buffers that may need to stay low too. Also
> +		 * make sure we allocate enough extra low memory so that we
> +		 * don't run out of DMA buffers for 32-bit devices.
> +		 */
> +		low_size = max(swiotlb_size_or_default() + (8UL << 20),
> +				256UL << 20);
> +#else
> +		/*
> +		 * in arm64, reserve low memory if and only if crashkernel=X,low
> +		 * specified.
> +		 */
> +		return -EINVAL;
> +#endif
> +	} else {
> +		/* passed with crashkernel=0,low ? */
> +		if (!low_size)
> +			return 0;
> +	}
> +
> +	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> +	if (!low_base) {
> +		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> +		       (unsigned long)(low_size >> 20));
> +		return -ENOMEM;
> +	}
> +
> +	ret = memblock_reserve(low_base, low_size);
> +	if (ret) {
> +		pr_err("%s: Error reserving crashkernel low memblock.\n",
> +				__func__);
> +		return ret;
> +	}
> +
> +	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> +		(unsigned long)(low_size >> 20),
> +		(unsigned long)(low_base >> 20),
> +		(unsigned long)(total_low_mem >> 20));
> +
> +	crashk_low_res.start = low_base;
> +	crashk_low_res.end   = low_base + low_size - 1;
> +#endif
> +	return 0;
> +}
> +
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len)
>  {
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index c19c0dad1ebe..db66bbabfff3 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
>  /* Flag to indicate we are going to kexec a new kernel */
>  bool kexec_in_progress = false;
>  
> -
> -/* Location of the reserved area for the crash kernel */
> -struct resource crashk_res = {
> -	.name  = "Crash kernel",
> -	.start = 0,
> -	.end   = 0,
> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> -	.desc  = IORES_DESC_CRASH_KERNEL
> -};
> -struct resource crashk_low_res = {
> -	.name  = "Crash kernel",
> -	.start = 0,
> -	.end   = 0,
> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> -	.desc  = IORES_DESC_CRASH_KERNEL
> -};
> -
>  int kexec_should_crash(struct task_struct *p)
>  {
>  	/*
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

Acked-by: Dave Young <dyoung@redhat.com>

Thanks
Dave

Re: [PATCH v9 1/5] x86: kdump: move reserve_crashkernel_low() into crash_core.c

[Dave Young]

On 06/28/20 at 04:34pm, Chen Zhou wrote:
> In preparation for supporting reserve_crashkernel_low in arm64 as
> x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.
> 
> BTW, move x86_64 CRASH_ALIGN to 2M suggested by Dave. CONFIG_PHYSICAL_ALIGN
> can be selected from 2M to 16M, move to the same as arm64.
> 
> Note, in arm64, we reserve low memory if and only if crashkernel=X,low
> is specified. Different with x86_64, don't set low memory automatically.
> 
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> ---
>  arch/x86/kernel/setup.c    | 66 ++++-------------------------
>  include/linux/crash_core.h |  3 ++
>  include/linux/kexec.h      |  2 -
>  kernel/crash_core.c        | 85 ++++++++++++++++++++++++++++++++++++++
>  kernel/kexec_core.c        | 17 --------
>  5 files changed, 96 insertions(+), 77 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index a3767e74c758..33db99ae3035 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -401,8 +401,8 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  
>  #ifdef CONFIG_KEXEC_CORE
>  
> -/* 16M alignment for crash kernel regions */
> -#define CRASH_ALIGN		SZ_16M
> +/* 2M alignment for crash kernel regions */
> +#define CRASH_ALIGN		SZ_2M
>  
>  /*
>   * Keep the crash kernel below this limit.
> @@ -425,59 +425,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  # define CRASH_ADDR_HIGH_MAX	SZ_64T
>  #endif
>  
> -static int __init reserve_crashkernel_low(void)
> -{
> -#ifdef CONFIG_X86_64
> -	unsigned long long base, low_base = 0, low_size = 0;
> -	unsigned long total_low_mem;
> -	int ret;
> -
> -	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> -
> -	/* crashkernel=Y,low */
> -	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
> -	if (ret) {
> -		/*
> -		 * two parts from kernel/dma/swiotlb.c:
> -		 * -swiotlb size: user-specified with swiotlb= or default.
> -		 *
> -		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> -		 * to 8M for other buffers that may need to stay low too. Also
> -		 * make sure we allocate enough extra low memory so that we
> -		 * don't run out of DMA buffers for 32-bit devices.
> -		 */
> -		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> -	} else {
> -		/* passed with crashkernel=0,low ? */
> -		if (!low_size)
> -			return 0;
> -	}
> -
> -	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> -	if (!low_base) {
> -		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> -		       (unsigned long)(low_size >> 20));
> -		return -ENOMEM;
> -	}
> -
> -	ret = memblock_reserve(low_base, low_size);
> -	if (ret) {
> -		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
> -		return ret;
> -	}
> -
> -	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> -		(unsigned long)(low_size >> 20),
> -		(unsigned long)(low_base >> 20),
> -		(unsigned long)(total_low_mem >> 20));
> -
> -	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;
> -}
> -
>  static void __init reserve_crashkernel(void)
>  {
>  	unsigned long long crash_size, crash_base, total_mem;
> @@ -541,9 +488,12 @@ static void __init reserve_crashkernel(void)
>  		return;
>  	}
>  
> -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> -		memblock_free(crash_base, crash_size);
> -		return;
> +	if (crash_base >= (1ULL << 32)) {
> +		if (reserve_crashkernel_low()) {
> +			memblock_free(crash_base, crash_size);
> +			return;
> +		}
> +		insert_resource(&iomem_resource, &crashk_low_res);
>  	}
>  
>  	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 525510a9f965..4df8c0bff03e 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -63,6 +63,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
>  extern unsigned char *vmcoreinfo_data;
>  extern size_t vmcoreinfo_size;
>  extern u32 *vmcoreinfo_note;
> +extern struct resource crashk_res;
> +extern struct resource crashk_low_res;
>  
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
> @@ -74,5 +76,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
>  int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
> +int __init reserve_crashkernel_low(void);
>  
>  #endif /* LINUX_CRASH_CORE_H */
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index ea67910ae6b7..a460afdbab0f 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -330,8 +330,6 @@ extern int kexec_load_disabled;
>  
>  /* Location of a reserved region to hold the crash kernel.
>   */
> -extern struct resource crashk_res;
> -extern struct resource crashk_low_res;
>  extern note_buf_t __percpu *crash_notes;
>  
>  /* flag to track if kexec reboot is in progress */
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 9f1557b98468..a7580d291c37 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -7,6 +7,8 @@
>  #include <linux/crash_core.h>
>  #include <linux/utsname.h>
>  #include <linux/vmalloc.h>
> +#include <linux/memblock.h>
> +#include <linux/swiotlb.h>
>  
>  #include <asm/page.h>
>  #include <asm/sections.h>
> @@ -19,6 +21,22 @@ u32 *vmcoreinfo_note;
>  /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
>  static unsigned char *vmcoreinfo_data_safecopy;
>  
> +/* Location of the reserved area for the crash kernel */
> +struct resource crashk_res = {
> +	.name  = "Crash kernel",
> +	.start = 0,
> +	.end   = 0,
> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> +	.desc  = IORES_DESC_CRASH_KERNEL
> +};
> +struct resource crashk_low_res = {
> +	.name  = "Crash kernel",
> +	.start = 0,
> +	.end   = 0,
> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> +	.desc  = IORES_DESC_CRASH_KERNEL
> +};
> +
>  /*
>   * parsing the "crashkernel" commandline
>   *
> @@ -292,6 +310,73 @@ int __init parse_crashkernel_low(char *cmdline,
>  				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
>  }
>  
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> +#define CRASH_ALIGN		SZ_2M
> +#endif
> +
> +int __init reserve_crashkernel_low(void)
> +{
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> +	unsigned long long base, low_base = 0, low_size = 0;
> +	unsigned long total_low_mem;
> +	int ret;
> +
> +	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> +
> +	/* crashkernel=Y,low */
> +	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
> +			&base);
> +	if (ret) {
> +#ifdef CONFIG_X86_64
> +		/*
> +		 * two parts from lib/swiotlb.c:
> +		 * -swiotlb size: user-specified with swiotlb= or default.
> +		 *
> +		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> +		 * to 8M for other buffers that may need to stay low too. Also
> +		 * make sure we allocate enough extra low memory so that we
> +		 * don't run out of DMA buffers for 32-bit devices.
> +		 */
> +		low_size = max(swiotlb_size_or_default() + (8UL << 20),
> +				256UL << 20);
> +#else
> +		/*
> +		 * in arm64, reserve low memory if and only if crashkernel=X,low
> +		 * specified.
> +		 */
> +		return -EINVAL;
> +#endif
> +	} else {
> +		/* passed with crashkernel=0,low ? */
> +		if (!low_size)
> +			return 0;
> +	}
> +
> +	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> +	if (!low_base) {
> +		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> +		       (unsigned long)(low_size >> 20));
> +		return -ENOMEM;
> +	}
> +
> +	ret = memblock_reserve(low_base, low_size);
> +	if (ret) {
> +		pr_err("%s: Error reserving crashkernel low memblock.\n",
> +				__func__);
> +		return ret;
> +	}
> +
> +	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> +		(unsigned long)(low_size >> 20),
> +		(unsigned long)(low_base >> 20),
> +		(unsigned long)(total_low_mem >> 20));
> +
> +	crashk_low_res.start = low_base;
> +	crashk_low_res.end   = low_base + low_size - 1;
> +#endif
> +	return 0;
> +}
> +
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len)
>  {
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index c19c0dad1ebe..db66bbabfff3 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
>  /* Flag to indicate we are going to kexec a new kernel */
>  bool kexec_in_progress = false;
>  
> -
> -/* Location of the reserved area for the crash kernel */
> -struct resource crashk_res = {
> -	.name  = "Crash kernel",
> -	.start = 0,
> -	.end   = 0,
> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> -	.desc  = IORES_DESC_CRASH_KERNEL
> -};
> -struct resource crashk_low_res = {
> -	.name  = "Crash kernel",
> -	.start = 0,
> -	.end   = 0,
> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> -	.desc  = IORES_DESC_CRASH_KERNEL
> -};
> -
>  int kexec_should_crash(struct task_struct *p)
>  {
>  	/*
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

Acked-by: Dave Young <dyoung@redhat.com>

Thanks
Dave


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Re: [PATCH v9 1/5] x86: kdump: move reserve_crashkernel_low() into crash_core.c

[Dave Young]

On 06/28/20 at 04:34pm, Chen Zhou wrote:
> In preparation for supporting reserve_crashkernel_low in arm64 as
> x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.
> 
> BTW, move x86_64 CRASH_ALIGN to 2M suggested by Dave. CONFIG_PHYSICAL_ALIGN
> can be selected from 2M to 16M, move to the same as arm64.
> 
> Note, in arm64, we reserve low memory if and only if crashkernel=X,low
> is specified. Different with x86_64, don't set low memory automatically.
> 
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> ---
>  arch/x86/kernel/setup.c    | 66 ++++-------------------------
>  include/linux/crash_core.h |  3 ++
>  include/linux/kexec.h      |  2 -
>  kernel/crash_core.c        | 85 ++++++++++++++++++++++++++++++++++++++
>  kernel/kexec_core.c        | 17 --------
>  5 files changed, 96 insertions(+), 77 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index a3767e74c758..33db99ae3035 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -401,8 +401,8 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  
>  #ifdef CONFIG_KEXEC_CORE
>  
> -/* 16M alignment for crash kernel regions */
> -#define CRASH_ALIGN		SZ_16M
> +/* 2M alignment for crash kernel regions */
> +#define CRASH_ALIGN		SZ_2M
>  
>  /*
>   * Keep the crash kernel below this limit.
> @@ -425,59 +425,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  # define CRASH_ADDR_HIGH_MAX	SZ_64T
>  #endif
>  
> -static int __init reserve_crashkernel_low(void)
> -{
> -#ifdef CONFIG_X86_64
> -	unsigned long long base, low_base = 0, low_size = 0;
> -	unsigned long total_low_mem;
> -	int ret;
> -
> -	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> -
> -	/* crashkernel=Y,low */
> -	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
> -	if (ret) {
> -		/*
> -		 * two parts from kernel/dma/swiotlb.c:
> -		 * -swiotlb size: user-specified with swiotlb= or default.
> -		 *
> -		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> -		 * to 8M for other buffers that may need to stay low too. Also
> -		 * make sure we allocate enough extra low memory so that we
> -		 * don't run out of DMA buffers for 32-bit devices.
> -		 */
> -		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> -	} else {
> -		/* passed with crashkernel=0,low ? */
> -		if (!low_size)
> -			return 0;
> -	}
> -
> -	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> -	if (!low_base) {
> -		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> -		       (unsigned long)(low_size >> 20));
> -		return -ENOMEM;
> -	}
> -
> -	ret = memblock_reserve(low_base, low_size);
> -	if (ret) {
> -		pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
> -		return ret;
> -	}
> -
> -	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> -		(unsigned long)(low_size >> 20),
> -		(unsigned long)(low_base >> 20),
> -		(unsigned long)(total_low_mem >> 20));
> -
> -	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;
> -}
> -
>  static void __init reserve_crashkernel(void)
>  {
>  	unsigned long long crash_size, crash_base, total_mem;
> @@ -541,9 +488,12 @@ static void __init reserve_crashkernel(void)
>  		return;
>  	}
>  
> -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> -		memblock_free(crash_base, crash_size);
> -		return;
> +	if (crash_base >= (1ULL << 32)) {
> +		if (reserve_crashkernel_low()) {
> +			memblock_free(crash_base, crash_size);
> +			return;
> +		}
> +		insert_resource(&iomem_resource, &crashk_low_res);
>  	}
>  
>  	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 525510a9f965..4df8c0bff03e 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -63,6 +63,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
>  extern unsigned char *vmcoreinfo_data;
>  extern size_t vmcoreinfo_size;
>  extern u32 *vmcoreinfo_note;
> +extern struct resource crashk_res;
> +extern struct resource crashk_low_res;
>  
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
> @@ -74,5 +76,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
>  int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
> +int __init reserve_crashkernel_low(void);
>  
>  #endif /* LINUX_CRASH_CORE_H */
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index ea67910ae6b7..a460afdbab0f 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -330,8 +330,6 @@ extern int kexec_load_disabled;
>  
>  /* Location of a reserved region to hold the crash kernel.
>   */
> -extern struct resource crashk_res;
> -extern struct resource crashk_low_res;
>  extern note_buf_t __percpu *crash_notes;
>  
>  /* flag to track if kexec reboot is in progress */
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 9f1557b98468..a7580d291c37 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -7,6 +7,8 @@
>  #include <linux/crash_core.h>
>  #include <linux/utsname.h>
>  #include <linux/vmalloc.h>
> +#include <linux/memblock.h>
> +#include <linux/swiotlb.h>
>  
>  #include <asm/page.h>
>  #include <asm/sections.h>
> @@ -19,6 +21,22 @@ u32 *vmcoreinfo_note;
>  /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
>  static unsigned char *vmcoreinfo_data_safecopy;
>  
> +/* Location of the reserved area for the crash kernel */
> +struct resource crashk_res = {
> +	.name  = "Crash kernel",
> +	.start = 0,
> +	.end   = 0,
> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> +	.desc  = IORES_DESC_CRASH_KERNEL
> +};
> +struct resource crashk_low_res = {
> +	.name  = "Crash kernel",
> +	.start = 0,
> +	.end   = 0,
> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> +	.desc  = IORES_DESC_CRASH_KERNEL
> +};
> +
>  /*
>   * parsing the "crashkernel" commandline
>   *
> @@ -292,6 +310,73 @@ int __init parse_crashkernel_low(char *cmdline,
>  				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
>  }
>  
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> +#define CRASH_ALIGN		SZ_2M
> +#endif
> +
> +int __init reserve_crashkernel_low(void)
> +{
> +#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
> +	unsigned long long base, low_base = 0, low_size = 0;
> +	unsigned long total_low_mem;
> +	int ret;
> +
> +	total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> +
> +	/* crashkernel=Y,low */
> +	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
> +			&base);
> +	if (ret) {
> +#ifdef CONFIG_X86_64
> +		/*
> +		 * two parts from lib/swiotlb.c:
> +		 * -swiotlb size: user-specified with swiotlb= or default.
> +		 *
> +		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> +		 * to 8M for other buffers that may need to stay low too. Also
> +		 * make sure we allocate enough extra low memory so that we
> +		 * don't run out of DMA buffers for 32-bit devices.
> +		 */
> +		low_size = max(swiotlb_size_or_default() + (8UL << 20),
> +				256UL << 20);
> +#else
> +		/*
> +		 * in arm64, reserve low memory if and only if crashkernel=X,low
> +		 * specified.
> +		 */
> +		return -EINVAL;
> +#endif
> +	} else {
> +		/* passed with crashkernel=0,low ? */
> +		if (!low_size)
> +			return 0;
> +	}
> +
> +	low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> +	if (!low_base) {
> +		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> +		       (unsigned long)(low_size >> 20));
> +		return -ENOMEM;
> +	}
> +
> +	ret = memblock_reserve(low_base, low_size);
> +	if (ret) {
> +		pr_err("%s: Error reserving crashkernel low memblock.\n",
> +				__func__);
> +		return ret;
> +	}
> +
> +	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> +		(unsigned long)(low_size >> 20),
> +		(unsigned long)(low_base >> 20),
> +		(unsigned long)(total_low_mem >> 20));
> +
> +	crashk_low_res.start = low_base;
> +	crashk_low_res.end   = low_base + low_size - 1;
> +#endif
> +	return 0;
> +}
> +
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len)
>  {
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index c19c0dad1ebe..db66bbabfff3 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
>  /* Flag to indicate we are going to kexec a new kernel */
>  bool kexec_in_progress = false;
>  
> -
> -/* Location of the reserved area for the crash kernel */
> -struct resource crashk_res = {
> -	.name  = "Crash kernel",
> -	.start = 0,
> -	.end   = 0,
> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> -	.desc  = IORES_DESC_CRASH_KERNEL
> -};
> -struct resource crashk_low_res = {
> -	.name  = "Crash kernel",
> -	.start = 0,
> -	.end   = 0,
> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> -	.desc  = IORES_DESC_CRASH_KERNEL
> -};
> -
>  int kexec_should_crash(struct task_struct *p)
>  {
>  	/*
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

Acked-by: Dave Young <dyoung@redhat.com>

Thanks
Dave


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http://lists.infradead.org/mailman/listinfo/kexec

Re: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[Dave Young]

Hi Chen,
On 06/28/20 at 04:34pm, Chen Zhou wrote:
> Now we support crashkernel=X,[low] on arm64, update the Documentation.
> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
> memory above 4G.
> 
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> ---
>  Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
>  Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
>  2 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
> index 2da65fef2a1c..6ba294d425c9 100644
> --- a/Documentation/admin-guide/kdump/kdump.rst
> +++ b/Documentation/admin-guide/kdump/kdump.rst
> @@ -299,7 +299,13 @@ Boot into System Kernel
>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>  
> -   On x86 and x86_64, use "crashkernel=64M@16M".
> +   On x86 use "crashkernel=64M@16M".
> +
> +   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
> +   fall back to reserve region above 4G when '@offset' hasn't been specified.

Actually crashkernel=Y without the offset works well, I do not see why
we need the offset, it should be some legacy thing.  So it should be
better just use the Y without offset here, and just leave a note
somewhere people can use [@X] offset when they really have to.

> +   We can also use "crashkernel=X,high" to select a region above 4G, which
> +   also tries to allocate at least 256M below 4G automatically and
> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>  
>     On ppc64, use "crashkernel=128M@32M".
>  
> @@ -316,8 +322,11 @@ Boot into System Kernel
>     kernel will automatically locate the crash kernel image within the
>     first 512MB of RAM if X is not given.
>  
> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
> +   On arm64, use "crashkernel=Y[@X]". Note that the start address of
>     the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
> +   If crashkernel=Z,low is specified simultaneously, reserve spcified size
> +   low memory for crash kdump kernel devices firstly and then reserve memory

"devices" seems not very accurate, maybe just drop the "for crash kdump
kernel devices" since it is clear based on the context.

> +   above 4G.
>  
>  Load the Dump-capture Kernel
>  ============================
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index fb95fad81c79..335431a351c0 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -722,6 +722,9 @@
>  			[KNL, x86_64] select a region under 4G first, and
>  			fall back to reserve region above 4G when '@offset'
>  			hasn't been specified.
> +			[KNL, arm64] If crashkernel=X,low is specified, reserve
> +			spcified size low memory for crash kdump kernel devices

Ditto.

> +			firstly, and then reserve memory above 4G.
>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>  
>  	crashkernel=range1:size1[,range2:size2,...][@offset]
> @@ -746,13 +749,23 @@
>  			requires at least 64M+32K low memory, also enough extra
>  			low memory is needed to make sure DMA buffers for 32-bit
>  			devices won't run out. Kernel would try to allocate at
> -			at least 256M below 4G automatically.
> +			least 256M below 4G automatically.
>  			This one let user to specify own low range under 4G
>  			for second kernel instead.
>  			0: to disable low allocation.
>  			It will be ignored when crashkernel=X,high is not used
>  			or memory reserved is below 4G.
> -
> +			[KNL, arm64] range under 4G.
> +			This one let user to specify own low range under 4G
> +			for crash dump kernel instead.
> +			Different with x86_64, kernel allocates specified size

sounds better:
s/Different with/Be different from

s/allocates/reserves

> +			physical memory region only when this parameter is specified
> +			instead of trying to allocate at least 256M below 4G

s/allocate/reserve

> +			automatically.
> +			This parameter is used along with crashkernel=X when we

Could change the passive sentence to below:
"Use this parameter along with"

> +			want to reserve crashkernel above 4G. If there are devices
> +			need to use ZONE_DMA in crash dump kernel, it is also
> +			a good choice.
>  	cryptomgr.notests
>  			[KNL] Disable crypto self-tests
>  
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

Thanks
Dave

Re: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[Dave Young]

Hi Chen,
On 06/28/20 at 04:34pm, Chen Zhou wrote:
> Now we support crashkernel=X,[low] on arm64, update the Documentation.
> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
> memory above 4G.
> 
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> ---
>  Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
>  Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
>  2 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
> index 2da65fef2a1c..6ba294d425c9 100644
> --- a/Documentation/admin-guide/kdump/kdump.rst
> +++ b/Documentation/admin-guide/kdump/kdump.rst
> @@ -299,7 +299,13 @@ Boot into System Kernel
>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>  
> -   On x86 and x86_64, use "crashkernel=64M@16M".
> +   On x86 use "crashkernel=64M@16M".
> +
> +   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
> +   fall back to reserve region above 4G when '@offset' hasn't been specified.

Actually crashkernel=Y without the offset works well, I do not see why
we need the offset, it should be some legacy thing.  So it should be
better just use the Y without offset here, and just leave a note
somewhere people can use [@X] offset when they really have to.

> +   We can also use "crashkernel=X,high" to select a region above 4G, which
> +   also tries to allocate at least 256M below 4G automatically and
> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>  
>     On ppc64, use "crashkernel=128M@32M".
>  
> @@ -316,8 +322,11 @@ Boot into System Kernel
>     kernel will automatically locate the crash kernel image within the
>     first 512MB of RAM if X is not given.
>  
> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
> +   On arm64, use "crashkernel=Y[@X]". Note that the start address of
>     the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
> +   If crashkernel=Z,low is specified simultaneously, reserve spcified size
> +   low memory for crash kdump kernel devices firstly and then reserve memory

"devices" seems not very accurate, maybe just drop the "for crash kdump
kernel devices" since it is clear based on the context.

> +   above 4G.
>  
>  Load the Dump-capture Kernel
>  ============================
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index fb95fad81c79..335431a351c0 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -722,6 +722,9 @@
>  			[KNL, x86_64] select a region under 4G first, and
>  			fall back to reserve region above 4G when '@offset'
>  			hasn't been specified.
> +			[KNL, arm64] If crashkernel=X,low is specified, reserve
> +			spcified size low memory for crash kdump kernel devices

Ditto.

> +			firstly, and then reserve memory above 4G.
>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>  
>  	crashkernel=range1:size1[,range2:size2,...][@offset]
> @@ -746,13 +749,23 @@
>  			requires at least 64M+32K low memory, also enough extra
>  			low memory is needed to make sure DMA buffers for 32-bit
>  			devices won't run out. Kernel would try to allocate at
> -			at least 256M below 4G automatically.
> +			least 256M below 4G automatically.
>  			This one let user to specify own low range under 4G
>  			for second kernel instead.
>  			0: to disable low allocation.
>  			It will be ignored when crashkernel=X,high is not used
>  			or memory reserved is below 4G.
> -
> +			[KNL, arm64] range under 4G.
> +			This one let user to specify own low range under 4G
> +			for crash dump kernel instead.
> +			Different with x86_64, kernel allocates specified size

sounds better:
s/Different with/Be different from

s/allocates/reserves

> +			physical memory region only when this parameter is specified
> +			instead of trying to allocate at least 256M below 4G

s/allocate/reserve

> +			automatically.
> +			This parameter is used along with crashkernel=X when we

Could change the passive sentence to below:
"Use this parameter along with"

> +			want to reserve crashkernel above 4G. If there are devices
> +			need to use ZONE_DMA in crash dump kernel, it is also
> +			a good choice.
>  	cryptomgr.notests
>  			[KNL] Disable crypto self-tests
>  
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

Thanks
Dave


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Re: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[Dave Young]

Hi Chen,
On 06/28/20 at 04:34pm, Chen Zhou wrote:
> Now we support crashkernel=X,[low] on arm64, update the Documentation.
> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
> memory above 4G.
> 
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
> ---
>  Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
>  Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
>  2 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
> index 2da65fef2a1c..6ba294d425c9 100644
> --- a/Documentation/admin-guide/kdump/kdump.rst
> +++ b/Documentation/admin-guide/kdump/kdump.rst
> @@ -299,7 +299,13 @@ Boot into System Kernel
>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>  
> -   On x86 and x86_64, use "crashkernel=64M@16M".
> +   On x86 use "crashkernel=64M@16M".
> +
> +   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
> +   fall back to reserve region above 4G when '@offset' hasn't been specified.

Actually crashkernel=Y without the offset works well, I do not see why
we need the offset, it should be some legacy thing.  So it should be
better just use the Y without offset here, and just leave a note
somewhere people can use [@X] offset when they really have to.

> +   We can also use "crashkernel=X,high" to select a region above 4G, which
> +   also tries to allocate at least 256M below 4G automatically and
> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>  
>     On ppc64, use "crashkernel=128M@32M".
>  
> @@ -316,8 +322,11 @@ Boot into System Kernel
>     kernel will automatically locate the crash kernel image within the
>     first 512MB of RAM if X is not given.
>  
> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
> +   On arm64, use "crashkernel=Y[@X]". Note that the start address of
>     the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
> +   If crashkernel=Z,low is specified simultaneously, reserve spcified size
> +   low memory for crash kdump kernel devices firstly and then reserve memory

"devices" seems not very accurate, maybe just drop the "for crash kdump
kernel devices" since it is clear based on the context.

> +   above 4G.
>  
>  Load the Dump-capture Kernel
>  ============================
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index fb95fad81c79..335431a351c0 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -722,6 +722,9 @@
>  			[KNL, x86_64] select a region under 4G first, and
>  			fall back to reserve region above 4G when '@offset'
>  			hasn't been specified.
> +			[KNL, arm64] If crashkernel=X,low is specified, reserve
> +			spcified size low memory for crash kdump kernel devices

Ditto.

> +			firstly, and then reserve memory above 4G.
>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>  
>  	crashkernel=range1:size1[,range2:size2,...][@offset]
> @@ -746,13 +749,23 @@
>  			requires at least 64M+32K low memory, also enough extra
>  			low memory is needed to make sure DMA buffers for 32-bit
>  			devices won't run out. Kernel would try to allocate at
> -			at least 256M below 4G automatically.
> +			least 256M below 4G automatically.
>  			This one let user to specify own low range under 4G
>  			for second kernel instead.
>  			0: to disable low allocation.
>  			It will be ignored when crashkernel=X,high is not used
>  			or memory reserved is below 4G.
> -
> +			[KNL, arm64] range under 4G.
> +			This one let user to specify own low range under 4G
> +			for crash dump kernel instead.
> +			Different with x86_64, kernel allocates specified size

sounds better:
s/Different with/Be different from

s/allocates/reserves

> +			physical memory region only when this parameter is specified
> +			instead of trying to allocate at least 256M below 4G

s/allocate/reserve

> +			automatically.
> +			This parameter is used along with crashkernel=X when we

Could change the passive sentence to below:
"Use this parameter along with"

> +			want to reserve crashkernel above 4G. If there are devices
> +			need to use ZONE_DMA in crash dump kernel, it is also
> +			a good choice.
>  	cryptomgr.notests
>  			[KNL] Disable crypto self-tests
>  
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

Thanks
Dave


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Re: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[chenzhou]

Hi Dave,


On 2020/7/2 10:59, Dave Young wrote:
> Hi Chen,
> On 06/28/20 at 04:34pm, Chen Zhou wrote:
>> Now we support crashkernel=X,[low] on arm64, update the Documentation.
>> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
>> memory above 4G.
>>
>> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
>> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
>> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
>> ---
>>  Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
>>  Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
>>  2 files changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
>> index 2da65fef2a1c..6ba294d425c9 100644
>> --- a/Documentation/admin-guide/kdump/kdump.rst
>> +++ b/Documentation/admin-guide/kdump/kdump.rst
>> @@ -299,7 +299,13 @@ Boot into System Kernel
>>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>>  
>> -   On x86 and x86_64, use "crashkernel=64M@16M".
>> +   On x86 use "crashkernel=64M@16M".
>> +
>> +   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
>> +   fall back to reserve region above 4G when '@offset' hasn't been specified.
> Actually crashkernel=Y without the offset works well, I do not see why
> we need the offset, it should be some legacy thing.  So it should be
> better just use the Y without offset here, and just leave a note
> somewhere people can use [@X] offset when they really have to.
>
>> +   We can also use "crashkernel=X,high" to select a region above 4G, which
>> +   also tries to allocate at least 256M below 4G automatically and
>> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>>  
>>     On ppc64, use "crashkernel=128M@32M".
>>  
>> @@ -316,8 +322,11 @@ Boot into System Kernel
>>     kernel will automatically locate the crash kernel image within the
>>     first 512MB of RAM if X is not given.
>>  
>> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
>> +   On arm64, use "crashkernel=Y[@X]". Note that the start address of
>>     the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
>> +   If crashkernel=Z,low is specified simultaneously, reserve spcified size
>> +   low memory for crash kdump kernel devices firstly and then reserve memory
> "devices" seems not very accurate, maybe just drop the "for crash kdump
> kernel devices" since it is clear based on the context.
>
>> +   above 4G.
>>  
>>  Load the Dump-capture Kernel
>>  ============================
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index fb95fad81c79..335431a351c0 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -722,6 +722,9 @@
>>  			[KNL, x86_64] select a region under 4G first, and
>>  			fall back to reserve region above 4G when '@offset'
>>  			hasn't been specified.
>> +			[KNL, arm64] If crashkernel=X,low is specified, reserve
>> +			spcified size low memory for crash kdump kernel devices
> Ditto.
>
>> +			firstly, and then reserve memory above 4G.
>>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>>  
>>  	crashkernel=range1:size1[,range2:size2,...][@offset]
>> @@ -746,13 +749,23 @@
>>  			requires at least 64M+32K low memory, also enough extra
>>  			low memory is needed to make sure DMA buffers for 32-bit
>>  			devices won't run out. Kernel would try to allocate at
>> -			at least 256M below 4G automatically.
>> +			least 256M below 4G automatically.
>>  			This one let user to specify own low range under 4G
>>  			for second kernel instead.
>>  			0: to disable low allocation.
>>  			It will be ignored when crashkernel=X,high is not used
>>  			or memory reserved is below 4G.
>> -
>> +			[KNL, arm64] range under 4G.
>> +			This one let user to specify own low range under 4G
>> +			for crash dump kernel instead.
>> +			Different with x86_64, kernel allocates specified size
> sounds better:
> s/Different with/Be different from
>
> s/allocates/reserves
>
>> +			physical memory region only when this parameter is specified
>> +			instead of trying to allocate at least 256M below 4G
> s/allocate/reserve
>
>> +			automatically.
>> +			This parameter is used along with crashkernel=X when we
> Could change the passive sentence to below:
> "Use this parameter along with"
Thanks for your review and suggestions. I will update these in next version.

Thanks,
Chen Zhou
>> +			want to reserve crashkernel above 4G. If there are devices
>> +			need to use ZONE_DMA in crash dump kernel, it is also
>> +			a good choice.
>>  	cryptomgr.notests
>>  			[KNL] Disable crypto self-tests
>>  
>> -- 
>> 2.20.1
>>
>>
>> _______________________________________________
>> kexec mailing list
>> kexec@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/kexec
>>
> Thanks
> Dave
>
>
> .
>

Re: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[chenzhou]

Hi Dave,


On 2020/7/2 10:59, Dave Young wrote:
> Hi Chen,
> On 06/28/20 at 04:34pm, Chen Zhou wrote:
>> Now we support crashkernel=X,[low] on arm64, update the Documentation.
>> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
>> memory above 4G.
>>
>> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
>> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
>> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
>> ---
>>  Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
>>  Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
>>  2 files changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
>> index 2da65fef2a1c..6ba294d425c9 100644
>> --- a/Documentation/admin-guide/kdump/kdump.rst
>> +++ b/Documentation/admin-guide/kdump/kdump.rst
>> @@ -299,7 +299,13 @@ Boot into System Kernel
>>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>>  
>> -   On x86 and x86_64, use "crashkernel=64M@16M".
>> +   On x86 use "crashkernel=64M@16M".
>> +
>> +   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
>> +   fall back to reserve region above 4G when '@offset' hasn't been specified.
> Actually crashkernel=Y without the offset works well, I do not see why
> we need the offset, it should be some legacy thing.  So it should be
> better just use the Y without offset here, and just leave a note
> somewhere people can use [@X] offset when they really have to.
>
>> +   We can also use "crashkernel=X,high" to select a region above 4G, which
>> +   also tries to allocate at least 256M below 4G automatically and
>> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>>  
>>     On ppc64, use "crashkernel=128M@32M".
>>  
>> @@ -316,8 +322,11 @@ Boot into System Kernel
>>     kernel will automatically locate the crash kernel image within the
>>     first 512MB of RAM if X is not given.
>>  
>> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
>> +   On arm64, use "crashkernel=Y[@X]". Note that the start address of
>>     the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
>> +   If crashkernel=Z,low is specified simultaneously, reserve spcified size
>> +   low memory for crash kdump kernel devices firstly and then reserve memory
> "devices" seems not very accurate, maybe just drop the "for crash kdump
> kernel devices" since it is clear based on the context.
>
>> +   above 4G.
>>  
>>  Load the Dump-capture Kernel
>>  ============================
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index fb95fad81c79..335431a351c0 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -722,6 +722,9 @@
>>  			[KNL, x86_64] select a region under 4G first, and
>>  			fall back to reserve region above 4G when '@offset'
>>  			hasn't been specified.
>> +			[KNL, arm64] If crashkernel=X,low is specified, reserve
>> +			spcified size low memory for crash kdump kernel devices
> Ditto.
>
>> +			firstly, and then reserve memory above 4G.
>>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>>  
>>  	crashkernel=range1:size1[,range2:size2,...][@offset]
>> @@ -746,13 +749,23 @@
>>  			requires at least 64M+32K low memory, also enough extra
>>  			low memory is needed to make sure DMA buffers for 32-bit
>>  			devices won't run out. Kernel would try to allocate at
>> -			at least 256M below 4G automatically.
>> +			least 256M below 4G automatically.
>>  			This one let user to specify own low range under 4G
>>  			for second kernel instead.
>>  			0: to disable low allocation.
>>  			It will be ignored when crashkernel=X,high is not used
>>  			or memory reserved is below 4G.
>> -
>> +			[KNL, arm64] range under 4G.
>> +			This one let user to specify own low range under 4G
>> +			for crash dump kernel instead.
>> +			Different with x86_64, kernel allocates specified size
> sounds better:
> s/Different with/Be different from
>
> s/allocates/reserves
>
>> +			physical memory region only when this parameter is specified
>> +			instead of trying to allocate at least 256M below 4G
> s/allocate/reserve
>
>> +			automatically.
>> +			This parameter is used along with crashkernel=X when we
> Could change the passive sentence to below:
> "Use this parameter along with"
Thanks for your review and suggestions. I will update these in next version.

Thanks,
Chen Zhou
>> +			want to reserve crashkernel above 4G. If there are devices
>> +			need to use ZONE_DMA in crash dump kernel, it is also
>> +			a good choice.
>>  	cryptomgr.notests
>>  			[KNL] Disable crypto self-tests
>>  
>> -- 
>> 2.20.1
>>
>>
>> _______________________________________________
>> kexec mailing list
>> kexec@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/kexec
>>
> Thanks
> Dave
>
>
> .
>



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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v9 5/5] kdump: update Documentation about crashkernel on arm64

[chenzhou]

Hi Dave,


On 2020/7/2 10:59, Dave Young wrote:
> Hi Chen,
> On 06/28/20 at 04:34pm, Chen Zhou wrote:
>> Now we support crashkernel=X,[low] on arm64, update the Documentation.
>> We could use parameters "crashkernel=X crashkernel=Y,low" to reserve
>> memory above 4G.
>>
>> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
>> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
>> Tested-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
>> ---
>>  Documentation/admin-guide/kdump/kdump.rst       | 13 +++++++++++--
>>  Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++--
>>  2 files changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
>> index 2da65fef2a1c..6ba294d425c9 100644
>> --- a/Documentation/admin-guide/kdump/kdump.rst
>> +++ b/Documentation/admin-guide/kdump/kdump.rst
>> @@ -299,7 +299,13 @@ Boot into System Kernel
>>     "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
>>     starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
>>  
>> -   On x86 and x86_64, use "crashkernel=64M@16M".
>> +   On x86 use "crashkernel=64M@16M".
>> +
>> +   On x86_64, use "crashkernel=Y[@X]" to select a region under 4G first, and
>> +   fall back to reserve region above 4G when '@offset' hasn't been specified.
> Actually crashkernel=Y without the offset works well, I do not see why
> we need the offset, it should be some legacy thing.  So it should be
> better just use the Y without offset here, and just leave a note
> somewhere people can use [@X] offset when they really have to.
>
>> +   We can also use "crashkernel=X,high" to select a region above 4G, which
>> +   also tries to allocate at least 256M below 4G automatically and
>> +   "crashkernel=Y,low" can be used to allocate specified size low memory.
>>  
>>     On ppc64, use "crashkernel=128M@32M".
>>  
>> @@ -316,8 +322,11 @@ Boot into System Kernel
>>     kernel will automatically locate the crash kernel image within the
>>     first 512MB of RAM if X is not given.
>>  
>> -   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
>> +   On arm64, use "crashkernel=Y[@X]". Note that the start address of
>>     the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
>> +   If crashkernel=Z,low is specified simultaneously, reserve spcified size
>> +   low memory for crash kdump kernel devices firstly and then reserve memory
> "devices" seems not very accurate, maybe just drop the "for crash kdump
> kernel devices" since it is clear based on the context.
>
>> +   above 4G.
>>  
>>  Load the Dump-capture Kernel
>>  ============================
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index fb95fad81c79..335431a351c0 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -722,6 +722,9 @@
>>  			[KNL, x86_64] select a region under 4G first, and
>>  			fall back to reserve region above 4G when '@offset'
>>  			hasn't been specified.
>> +			[KNL, arm64] If crashkernel=X,low is specified, reserve
>> +			spcified size low memory for crash kdump kernel devices
> Ditto.
>
>> +			firstly, and then reserve memory above 4G.
>>  			See Documentation/admin-guide/kdump/kdump.rst for further details.
>>  
>>  	crashkernel=range1:size1[,range2:size2,...][@offset]
>> @@ -746,13 +749,23 @@
>>  			requires at least 64M+32K low memory, also enough extra
>>  			low memory is needed to make sure DMA buffers for 32-bit
>>  			devices won't run out. Kernel would try to allocate at
>> -			at least 256M below 4G automatically.
>> +			least 256M below 4G automatically.
>>  			This one let user to specify own low range under 4G
>>  			for second kernel instead.
>>  			0: to disable low allocation.
>>  			It will be ignored when crashkernel=X,high is not used
>>  			or memory reserved is below 4G.
>> -
>> +			[KNL, arm64] range under 4G.
>> +			This one let user to specify own low range under 4G
>> +			for crash dump kernel instead.
>> +			Different with x86_64, kernel allocates specified size
> sounds better:
> s/Different with/Be different from
>
> s/allocates/reserves
>
>> +			physical memory region only when this parameter is specified
>> +			instead of trying to allocate at least 256M below 4G
> s/allocate/reserve
>
>> +			automatically.
>> +			This parameter is used along with crashkernel=X when we
> Could change the passive sentence to below:
> "Use this parameter along with"
Thanks for your review and suggestions. I will update these in next version.

Thanks,
Chen Zhou
>> +			want to reserve crashkernel above 4G. If there are devices
>> +			need to use ZONE_DMA in crash dump kernel, it is also
>> +			a good choice.
>>  	cryptomgr.notests
>>  			[KNL] Disable crypto self-tests
>>  
>> -- 
>> 2.20.1
>>
>>
>> _______________________________________________
>> kexec mailing list
>> kexec@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/kexec
>>
> Thanks
> Dave
>
>
> .
>



_______________________________________________
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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec