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Subject[PATCH 4.4 13/21] x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@intel.com>

commit 917db484dc6a69969d317b3e57add4208a8d9d42 upstream.

In commit:

ec776ef6bbe1 ("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that functionality has since been replaced by devm_memremap_pages().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: 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: ec776ef6bbe1 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/e820.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -347,7 +347,7 @@ int __init sanitize_e820_map(struct e820
* 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;
@@ -753,7 +753,7 @@ u64 __init early_reserve_e820(u64 size,
/*
* 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;
@@ -764,11 +764,7 @@ static unsigned long __init e820_end_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;
@@ -793,12 +789,12 @@ static unsigned long __init e820_end_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 early_panic(char *msg)

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