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

[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: <stable@vger.kernel.org>
Cc: Zhang Yi <yizhan@redhat.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Dave Chinner <david@fromorbit.com>
Fixes: 917db484dc6a ("x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation")
Signed-off-by: Dan Williams <dan.j.williams@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;

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

[Dan Williams]

On Wed, Oct 12, 2016 at 11:01 AM, Dan Williams <dan.j.williams@intel.com> wrote:
> 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: <stable@vger.kernel.org>
> Cc: Zhang Yi <yizhan@redhat.com>
> Cc: Jeff Moyer <jmoyer@redhat.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Reported-by: Dave Chinner <david@fromorbit.com>
> Fixes: 917db484dc6a ("x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation")
> Signed-off-by: Dan Williams <dan.j.williams@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;
>

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:x86/urgent] x86/e820: Don't merge consecutive E820_PRAM ranges

[tip-bot for Dan Williams]

Commit-ID:  23446cb66c073b827779e5eb3dec301623299b32
Gitweb:     http://git.kernel.org/tip/23446cb66c073b827779e5eb3dec301623299b32
Author:     Dan Williams <dan.j.williams@intel.com>
AuthorDate: Wed, 12 Oct 2016 11:01:48 -0700
Committer:  Ingo Molnar <mingo@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 <david@fromorbit.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Zhang Yi <yizhan@redhat.com>
Cc: linux-nvdimm@lists.01.org
Fixes: 917db484dc6a ("x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation")
Link: http://lkml.kernel.org/r/147629530854.10618.10383744751594021268.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@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
--- 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;