[PATCH] x86/e820: don't merge consecutive E820_PRAM ranges

[Dan Williams]

Commit 917db484dc6a "x86/boot: Fix kdump, cleanup aborted E820_PRAM
max_pfn manipulation" fixed up the broken manipulations of max_pfn in
the presence of E820_PRAM ranges. However, it also broke the
sanitize_e820_map() support for not merging E820_PRAM ranges.
Re-introduce the enabling to keep resource boundaries between
consecutive defined ranges. Otherwise, for example, an environment that
boots with memmap=2G!8G,2G!10G will end up with a single 4G /dev/pmem0
device instead of a /dev/pmem0 and /dev/pmem1 device 2G in size.

Cc: <sta...@vger.kernel.org>
Cc: Zhang Yi <yiz...@redhat.com>
Cc: Jeff Moyer <jmo...@redhat.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Thomas Gleixner <tg...@linutronix.de>
Reported-by: Dave Chinner <da...@fromorbit.com>
Fixes: 917db484dc6a ("x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation")
Signed-off-by: Dan Williams <dan.j.w...@intel.com>
---
arch/x86/kernel/e820.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index b85fe5f91c3f..90e8dde3ec26 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -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) {
+ if (current_type != last_type || current_type == E820_PRAM) {
if (last_type != 0) {
new_bios[new_bios_entry].size =
change_point[chgidx]->addr - last_addr;

[Dan Williams]

Hi Ingo, can you grab this one for 4.9-rc1? The regression is now
making its way to the -stable branches, so this fix is needed there
now as well.

Let me know, I can also just take it through libnvdimm.git with an ack.

[tip-bot for Dan Williams]

Commit-ID: 23446cb66c073b827779e5eb3dec301623299b32
Gitweb: http://git.kernel.org/tip/23446cb66c073b827779e5eb3dec301623299b32
Author: Dan Williams <dan.j.w...@intel.com>
AuthorDate: Wed, 12 Oct 2016 11:01:48 -0700
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Sun, 16 Oct 2016 11:16:48 +0200

x86/e820: Don't merge consecutive E820_PRAM ranges

Commit:

917db484dc6a ("x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation")

... fixed up the broken manipulations of max_pfn in the presence of

E820_PRAM ranges.

However, it also broke the sanitize_e820_map() support for not merging
E820_PRAM ranges.

Re-introduce the enabling to keep resource boundaries between
consecutive defined ranges. Otherwise, for example, an environment that
boots with memmap=2G!8G,2G!10G will end up with a single 4G /dev/pmem0
device instead of a /dev/pmem0 and /dev/pmem1 device 2G in size.

Reported-by: Dave Chinner <da...@fromorbit.com>
Signed-off-by: Dan Williams <dan.j.w...@intel.com>
Cc: <sta...@vger.kernel.org>
Cc: Andy Lutomirski <lu...@kernel.org>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Brian Gerst <brg...@gmail.com>
Cc: Denys Vlasenko <dvla...@redhat.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Jeff Moyer <jmo...@redhat.com>
Cc: Josh Poimboeuf <jpoi...@redhat.com>
Cc: Linus Torvalds <torv...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <tg...@linutronix.de>
Cc: Zhang Yi <yiz...@redhat.com>
Cc: linux-...@lists.01.org

Fixes: 917db484dc6a ("x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation")

Link: http://lkml.kernel.org/r/147629530854.10618.103...@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>

---
arch/x86/kernel/e820.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c

index b85fe5f..90e8dde 100644