Commit 917db484 authored Sep 21, 2016 by Dan Williams Committed by Ingo Molnar Sep 22, 2016

x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation

In commit:

  ec776ef6 ("x86/mm: Add support for the non-standard protected e820 type")

Christoph references the original patch I wrote implementing pmem support.
The intent of the 'max_pfn' changes in that commit were to enable persistent
memory ranges to be covered by the struct page memmap by default.

However, that approach was abandoned when Christoph ported the patches [1], and
that functionality has since been replaced by devm_memremap_pages().

In the meantime, this max_pfn manipulation is confusing kdump [2] that
assumes that everything covered by the max_pfn is "System RAM".  This
results in kdump hanging or crashing.

 [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-March/000348.html
 [2]: https://bugzilla.redhat.com/show_bug.cgi?id=1351098



So fix it.

Reported-by: Zhang Yi <yizhan@redhat.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Tested-by: Zhang Yi <yizhan@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: <stable@vger.kernel.org> # v4.1 and later kernels
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-nvdimm@lists.01.org
Fixes: ec776ef6 ("x86/mm: Add support for the non-standard protected e820 type")
Link: http://lkml.kernel.org/r/147448744538.34910.11287693517367139607.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 18278229

arch/x86/kernel/e820.c

+5 −9

Original line number	Diff line number	Diff line
		@@ -350,7 +350,7 @@ int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map,
		* continue building up new bios map based on this
		* information
		*/
		if (current_type != last_type \|\| current_type == E820_PRAM) {
		if (current_type != last_type) {
		if (last_type != 0) {
		new_bios[new_bios_entry].size =
		change_point[chgidx]->addr - last_addr;
		@@ -783,7 +783,7 @@ u64 __init early_reserve_e820(u64 size, u64 align)
		/*
		* Find the highest page frame number we have available
		*/
		static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
		static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
		{
		int i;
		unsigned long last_pfn = 0;
		@@ -794,11 +794,7 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
		unsigned long start_pfn;
		unsigned long end_pfn;

		/*
		* Persistent memory is accounted as ram for purposes of
		* establishing max_pfn and mem_map.
		*/
		if (ei->type != E820_RAM && ei->type != E820_PRAM)
		if (ei->type != type)
		continue;

		start_pfn = ei->addr >> PAGE_SHIFT;
		@@ -823,12 +819,12 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
		}
		unsigned long __init e820_end_of_ram_pfn(void)
		{
		return e820_end_pfn(MAX_ARCH_PFN);
		return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
		}

		unsigned long __init e820_end_of_low_ram_pfn(void)
		{
		return e820_end_pfn(1UL << (32-PAGE_SHIFT));
		return e820_end_pfn(1UL << (32 - PAGE_SHIFT), E820_RAM);
		}

		static void __init early_panic(char *msg)