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Merge branch 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 kdump update from Ingo Molnar:
 "This 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"

* 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kdump: Fall back to reserve high crashkernel memory
  x86/kdump: Have crashkernel=X reserve under 4G by default
This commit is contained in:
Linus Torvalds 2019-05-06 16:11:45 -07:00
parent 8f14772703 b9ac3849af
commit e913c4a4c2
2 changed files with 24 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Documentation/admin-guide/kernel-parameters.txt
View File

@ -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

32
arch/x86/kernel/setup.c
View File

@ -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;