Linus,
Please pull the latest x86-kdump-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-kdump-for-linus
# HEAD: b9ac3849af412fd3887d7652bdbabf29d2aecc16 x86/kdump: Fall back to
reserve high crashkernel memory
This tree includes two changes:
- Raise the crash kernel reservation limit from from ~896MB to ~4GB.
Only very old (and already known-broken) kexec-tools is supposed to be
affected by this negatively.
- Allow higher than 4GB crash kernel allocations when low allocations
fail.
Thanks,
Ingo
------------------>
Dave Young (2):
x86/kdump: Have crashkernel=X reserve under 4G by default
x86/kdump: Fall back to reserve high crashkernel memory
Documentation/admin-guide/kernel-parameters.txt | 7 ++++--
arch/x86/kernel/setup.c | 32 +++++++++++++++----------
2 files changed, 24 insertions(+), 15 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 2b8ee90bb644..24d01648edeb 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -704,8 +704,11 @@
upon panic. This parameter reserves the physical
memory region [offset, offset + size] for that kernel
image. If '@offset' is omitted, then a suitable offset
- is selected automatically. Check
- Documentation/kdump/kdump.txt for further details.
+ is selected automatically.
+ [KNL, x86_64] select a region under 4G first, and
+ fall back to reserve region above 4G when '@offset'
+ hasn't been specified.
+ See Documentation/kdump/kdump.txt for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 3d872a527cd9..c15f362a2516 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -71,6 +71,7 @@
#include <linux/tboot.h>
#include <linux/jiffies.h>
#include <linux/mem_encrypt.h>
+#include <linux/sizes.h>
#include <linux/usb/xhci-dbgp.h>
#include <video/edid.h>
@@ -448,18 +449,17 @@ static void __init
memblock_x86_reserve_range_setup_data(void)
#ifdef CONFIG_KEXEC_CORE
/* 16M alignment for crash kernel regions */
-#define CRASH_ALIGN (16 << 20)
+#define CRASH_ALIGN SZ_16M
/*
* Keep the crash kernel below this limit. On 32 bits earlier kernels
* would limit the kernel to the low 512 MiB due to mapping restrictions.
- * On 64bit, old kexec-tools need to under 896MiB.
*/
#ifdef CONFIG_X86_32
-# define CRASH_ADDR_LOW_MAX (512 << 20)
-# define CRASH_ADDR_HIGH_MAX (512 << 20)
+# define CRASH_ADDR_LOW_MAX SZ_512M
+# define CRASH_ADDR_HIGH_MAX SZ_512M
#else
-# define CRASH_ADDR_LOW_MAX (896UL << 20)
+# define CRASH_ADDR_LOW_MAX SZ_4G
# define CRASH_ADDR_HIGH_MAX MAXMEM
#endif
@@ -541,21 +541,27 @@ static void __init reserve_crashkernel(void)
}
/* 0 means: find the address automatically */
- if (crash_base <= 0) {
+ if (!crash_base) {
/*
* Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
- * as old kexec-tools loads bzImage below that, unless
- * "crashkernel=size[KMG],high" is specified.
+ * crashkernel=x,high reserves memory over 4G, also allocates
+ * 256M extra low memory for DMA buffers and swiotlb.
+ * But the extra memory is not required for all machines.
+ * So try low memory first and fall back to high memory
+ * unless "crashkernel=size[KMG],high" is specified.
*/
- crash_base = memblock_find_in_range(CRASH_ALIGN,
- high ? CRASH_ADDR_HIGH_MAX
- : CRASH_ADDR_LOW_MAX,
- crash_size, CRASH_ALIGN);
+ if (!high)
+ crash_base = memblock_find_in_range(CRASH_ALIGN,
+ CRASH_ADDR_LOW_MAX,
+ crash_size, CRASH_ALIGN);
+ if (!crash_base)
+ crash_base = memblock_find_in_range(CRASH_ALIGN,
+ CRASH_ADDR_HIGH_MAX,
+ crash_size, CRASH_ALIGN);
if (!crash_base) {
pr_info("crashkernel reservation failed - No suitable
area found.\n");
return;
}
-
} else {
unsigned long long start;
