Commit e913c4a4 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 8f147727 b9ac3849

Documentation/admin-guide/kernel-parameters.txt

+5 −2
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/setup.c

+19 −13
Original line number Diff line number Diff line
@@ -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.

		 */

		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,

						    high ? CRASH_ADDR_HIGH_MAX

							 : CRASH_ADDR_LOW_MAX,

						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;

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