diff mbox

[External,RFC,v1,3/6] mm, zone_type: create ZONE_NVM and fill into GFP_ZONE_TABLE

Message ID HK2PR03MB1684653383FFEDAE9B41A548929A0@HK2PR03MB1684.apcprd03.prod.outlook.com (mailing list archive)
State New, archived
Headers show

Commit Message

Huaisheng HS1 Ye May 8, 2018, 2:33 a.m. UTC 
Expand ZONE_NVM into enum zone_type, and create GFP_NVM
which represents gfp_t flag for NVM zone.

Because there is no lower plain integer GFP bitmask can be
used for ___GFP_NVM, a workable way is to get space from
GFP_ZONE_BAD to fill ZONE_NVM into GFP_ZONE_TABLE.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Signed-off-by: Ocean He <hehy1@lenovo.com>
---
 include/linux/gfp.h    | 57 +++++++++++++++++++++++++++++++++++++++++++++++---
 include/linux/mmzone.h |  3 +++
 mm/Kconfig             | 16 ++++++++++++++
 mm/page_alloc.c        |  3 +++
 4 files changed, 76 insertions(+), 3 deletions(-)

Comments

Randy Dunlap May 8, 2018, 4:43 a.m. UTC | #1 
On 05/07/2018 07:33 PM, Huaisheng HS1 Ye wrote:
> diff --git a/mm/Kconfig b/mm/Kconfig
> index c782e8f..5fe1f63 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -687,6 +687,22 @@ config ZONE_DEVICE
>  
> +config ZONE_NVM
> +	bool "Manage NVDIMM (pmem) by memory management (EXPERIMENTAL)"
> +	depends on NUMA && X86_64

Hi,
I'm curious why this depends on NUMA. Couldn't it be useful in non-NUMA
(i.e., UMA) configs?

Thanks.

> +	depends on HAVE_MEMBLOCK_NODE_MAP
> +	depends on HAVE_MEMBLOCK
> +	depends on !IA32_EMULATION
> +	default n
> +
> +	help
> +	  This option allows you to use memory management subsystem to manage
> +	  NVDIMM (pmem). With it mm can arrange NVDIMMs into real physical zones
> +	  like NORMAL and DMA32. That means buddy system and swap can be used
> +	  directly to NVDIMM zone. This feature is beneficial to recover
> +	  dirty pages from power fail or system crash by storing write cache
> +	  to NVDIMM zone.
Huaisheng HS1 Ye May 9, 2018, 4:22 a.m. UTC | #2 
> On 05/07/2018 07:33 PM, Huaisheng HS1 Ye wrote:

> > diff --git a/mm/Kconfig b/mm/Kconfig

> > index c782e8f..5fe1f63 100644

> > --- a/mm/Kconfig

> > +++ b/mm/Kconfig

> > @@ -687,6 +687,22 @@ config ZONE_DEVICE

> >

> > +config ZONE_NVM

> > +	bool "Manage NVDIMM (pmem) by memory management (EXPERIMENTAL)"

> > +	depends on NUMA && X86_64

> 

> Hi,

> I'm curious why this depends on NUMA. Couldn't it be useful in non-NUMA

> (i.e., UMA) configs?

> 

I wrote these patches with two sockets testing platform, and there are two DDRs and two NVDIMMs have been installed to it.
So, for every socket it has one DDR and one NVDIMM with it. Here is memory region from memblock, you can get its distribution.

 435 [    0.000000] Zone ranges:
 436 [    0.000000]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]
 437 [    0.000000]   DMA32    [mem 0x0000000001000000-0x00000000ffffffff]
 438 [    0.000000]   Normal   [mem 0x0000000100000000-0x00000046bfffffff]
 439 [    0.000000]   NVM      [mem 0x0000000440000000-0x00000046bfffffff]
 440 [    0.000000]   Device   empty
 441 [    0.000000] Movable zone start for each node
 442 [    0.000000] Early memory node ranges
 443 [    0.000000]   node   0: [mem 0x0000000000001000-0x000000000009ffff]
 444 [    0.000000]   node   0: [mem 0x0000000000100000-0x00000000a69c2fff]
 445 [    0.000000]   node   0: [mem 0x00000000a7654000-0x00000000a85eefff]
 446 [    0.000000]   node   0: [mem 0x00000000ab399000-0x00000000af3f6fff]
 447 [    0.000000]   node   0: [mem 0x00000000af429000-0x00000000af7fffff]
 448 [    0.000000]   node   0: [mem 0x0000000100000000-0x000000043fffffff]	Normal 0
 449 [    0.000000]   node   0: [mem 0x0000000440000000-0x000000237fffffff]	NVDIMM 0
 450 [    0.000000]   node   1: [mem 0x0000002380000000-0x000000277fffffff]	Normal 1
 451 [    0.000000]   node   1: [mem 0x0000002780000000-0x00000046bfffffff]	NVDIMM 1

If we disable NUMA, there is a result as Normal an NVDIMM zones will be overlapping with each other.
Current mm treats all memory regions equally, it divides zones just by size, like 16M for DMA, 4G for DMA32, and others above for Normal.
The spanned range of all zones couldn't be overlapped.

If we enable NUMA, for every socket its DDR and NVDIMM are separated, you can find that NVDIMM region always behind Normal zone.

Sincerely,
Huaisheng Ye
Michal Hocko May 9, 2018, 11:47 a.m. UTC | #3 
On Wed 09-05-18 04:22:10, Huaisheng HS1 Ye wrote:
> 
> > On 05/07/2018 07:33 PM, Huaisheng HS1 Ye wrote:
> > > diff --git a/mm/Kconfig b/mm/Kconfig
> > > index c782e8f..5fe1f63 100644
> > > --- a/mm/Kconfig
> > > +++ b/mm/Kconfig
> > > @@ -687,6 +687,22 @@ config ZONE_DEVICE
> > >
> > > +config ZONE_NVM
> > > +	bool "Manage NVDIMM (pmem) by memory management (EXPERIMENTAL)"
> > > +	depends on NUMA && X86_64
> > 
> > Hi,
> > I'm curious why this depends on NUMA. Couldn't it be useful in non-NUMA
> > (i.e., UMA) configs?
> > 
> I wrote these patches with two sockets testing platform, and there are two DDRs and two NVDIMMs have been installed to it.
> So, for every socket it has one DDR and one NVDIMM with it. Here is memory region from memblock, you can get its distribution.
> 
>  435 [    0.000000] Zone ranges:
>  436 [    0.000000]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]
>  437 [    0.000000]   DMA32    [mem 0x0000000001000000-0x00000000ffffffff]
>  438 [    0.000000]   Normal   [mem 0x0000000100000000-0x00000046bfffffff]
>  439 [    0.000000]   NVM      [mem 0x0000000440000000-0x00000046bfffffff]
>  440 [    0.000000]   Device   empty
>  441 [    0.000000] Movable zone start for each node
>  442 [    0.000000] Early memory node ranges
>  443 [    0.000000]   node   0: [mem 0x0000000000001000-0x000000000009ffff]
>  444 [    0.000000]   node   0: [mem 0x0000000000100000-0x00000000a69c2fff]
>  445 [    0.000000]   node   0: [mem 0x00000000a7654000-0x00000000a85eefff]
>  446 [    0.000000]   node   0: [mem 0x00000000ab399000-0x00000000af3f6fff]
>  447 [    0.000000]   node   0: [mem 0x00000000af429000-0x00000000af7fffff]
>  448 [    0.000000]   node   0: [mem 0x0000000100000000-0x000000043fffffff]	Normal 0
>  449 [    0.000000]   node   0: [mem 0x0000000440000000-0x000000237fffffff]	NVDIMM 0
>  450 [    0.000000]   node   1: [mem 0x0000002380000000-0x000000277fffffff]	Normal 1
>  451 [    0.000000]   node   1: [mem 0x0000002780000000-0x00000046bfffffff]	NVDIMM 1
> 
> If we disable NUMA, there is a result as Normal an NVDIMM zones will be overlapping with each other.
> Current mm treats all memory regions equally, it divides zones just by size, like 16M for DMA, 4G for DMA32, and others above for Normal.
> The spanned range of all zones couldn't be overlapped.

No, this is not correct. Zones can overlap.
Huaisheng HS1 Ye May 9, 2018, 2:04 p.m. UTC | #4 
> From: owner-linux-mm@kvack.org [mailto:owner-linux-mm@kvack.org] On Behalf Of Michal Hocko

> 

> On Wed 09-05-18 04:22:10, Huaisheng HS1 Ye wrote:

> >

> > > On 05/07/2018 07:33 PM, Huaisheng HS1 Ye wrote:

> > > > diff --git a/mm/Kconfig b/mm/Kconfig

> > > > index c782e8f..5fe1f63 100644

> > > > --- a/mm/Kconfig

> > > > +++ b/mm/Kconfig

> > > > @@ -687,6 +687,22 @@ config ZONE_DEVICE

> > > >

> > > > +config ZONE_NVM

> > > > +	bool "Manage NVDIMM (pmem) by memory management (EXPERIMENTAL)"

> > > > +	depends on NUMA && X86_64

> > >

> > > Hi,

> > > I'm curious why this depends on NUMA. Couldn't it be useful in non-NUMA

> > > (i.e., UMA) configs?

> > >

> > I wrote these patches with two sockets testing platform, and there are two DDRs and

> two NVDIMMs have been installed to it.

> > So, for every socket it has one DDR and one NVDIMM with it. Here is memory region

> from memblock, you can get its distribution.

> >

> >  435 [    0.000000] Zone ranges:

> >  436 [    0.000000]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]

> >  437 [    0.000000]   DMA32    [mem 0x0000000001000000-0x00000000ffffffff]

> >  438 [    0.000000]   Normal   [mem 0x0000000100000000-0x00000046bfffffff]

> >  439 [    0.000000]   NVM      [mem 0x0000000440000000-0x00000046bfffffff]

> >  440 [    0.000000]   Device   empty

> >  441 [    0.000000] Movable zone start for each node

> >  442 [    0.000000] Early memory node ranges

> >  443 [    0.000000]   node   0: [mem 0x0000000000001000-0x000000000009ffff]

> >  444 [    0.000000]   node   0: [mem 0x0000000000100000-0x00000000a69c2fff]

> >  445 [    0.000000]   node   0: [mem 0x00000000a7654000-0x00000000a85eefff]

> >  446 [    0.000000]   node   0: [mem 0x00000000ab399000-0x00000000af3f6fff]

> >  447 [    0.000000]   node   0: [mem 0x00000000af429000-0x00000000af7fffff]

> >  448 [    0.000000]   node   0: [mem 0x0000000100000000-0x000000043fffffff]	Normal 0

> >  449 [    0.000000]   node   0: [mem 0x0000000440000000-0x000000237fffffff]	NVDIMM 0

> >  450 [    0.000000]   node   1: [mem 0x0000002380000000-0x000000277fffffff]	Normal 1

> >  451 [    0.000000]   node   1: [mem 0x0000002780000000-0x00000046bfffffff]	NVDIMM 1

> >

> > If we disable NUMA, there is a result as Normal an NVDIMM zones will be overlapping

> with each other.

> > Current mm treats all memory regions equally, it divides zones just by size, like

> 16M for DMA, 4G for DMA32, and others above for Normal.

> > The spanned range of all zones couldn't be overlapped.

> 

> No, this is not correct. Zones can overlap.


Hi Michal,

Thanks for pointing it out.
But function zone_sizes_init decides arch_zone_lowest/highest_possible_pfn's size by max_low_pfn, then free_area_init_nodes/node are responsible for calculating the spanned size of zones from memblock memory regions.
So, ZONE_DMA and ZONE_DMA32 and ZONE_NORMAL have separate address scope. How can they be overlapped with each other?

Sincerely,
Huaisheng Ye | εΆζ€€θƒœ
Linux kernel | Lenovo
Michal Hocko May 9, 2018, 8:56 p.m. UTC | #5 
On Wed 09-05-18 14:04:21, Huaisheng HS1 Ye wrote:
> > From: owner-linux-mm@kvack.org [mailto:owner-linux-mm@kvack.org] On Behalf Of Michal Hocko
> > 
> > On Wed 09-05-18 04:22:10, Huaisheng HS1 Ye wrote:
[...]
> > > Current mm treats all memory regions equally, it divides zones just by size, like
> > 16M for DMA, 4G for DMA32, and others above for Normal.
> > > The spanned range of all zones couldn't be overlapped.
> > 
> > No, this is not correct. Zones can overlap.
> 
> Hi Michal,
> 
> Thanks for pointing it out.
> But function zone_sizes_init decides
> arch_zone_lowest/highest_possible_pfn's size by max_low_pfn, then
> free_area_init_nodes/node are responsible for calculating the spanned
> size of zones from memblock memory regions.  So, ZONE_DMA and
> ZONE_DMA32 and ZONE_NORMAL have separate address scope. How can they
> be overlapped with each other?

Sorry, I could have been a bit more specific. DMA, DMA32 and Normal
zones are exclusive. They are mapped to a specific physical range of
memory so they cannot overlap. I was referring to a general property
that zones might interleave. Especially zone Normal, Movable and Device.
Huaisheng HS1 Ye May 10, 2018, 3:53 a.m. UTC | #6 
> 
> On Wed 09-05-18 14:04:21, Huaisheng HS1 Ye wrote:
> > > From: owner-linux-mm@kvack.org [mailto:owner-linux-mm@kvack.org] On Behalf Of
> Michal Hocko
> > >
> > > On Wed 09-05-18 04:22:10, Huaisheng HS1 Ye wrote:
> [...]
> > > > Current mm treats all memory regions equally, it divides zones just by size,
> like
> > > 16M for DMA, 4G for DMA32, and others above for Normal.
> > > > The spanned range of all zones couldn't be overlapped.
> > >
> > > No, this is not correct. Zones can overlap.
> >
> > Hi Michal,
> >
> > Thanks for pointing it out.
> > But function zone_sizes_init decides
> > arch_zone_lowest/highest_possible_pfn's size by max_low_pfn, then
> > free_area_init_nodes/node are responsible for calculating the spanned
> > size of zones from memblock memory regions.  So, ZONE_DMA and
> > ZONE_DMA32 and ZONE_NORMAL have separate address scope. How can they
> > be overlapped with each other?
> 
> Sorry, I could have been a bit more specific. DMA, DMA32 and Normal
> zones are exclusive. They are mapped to a specific physical range of
> memory so they cannot overlap. I was referring to a general property
> that zones might interleave. Especially zone Normal, Movable and Device.

Exactly, here ZONE_NVM is a real physical range same as ZONE_DMA, ZONE_DMA32 and ZONE_Normal. So, it couldn't overlap with other zones.
Just like you mentioned, ZONE_MOVABLE is virtual zone, which comes ZONE_Normal.
The way of virtual zone is another implementation compared with current patch for ZONE_NVM.
It has advantages but also disadvantages, which need to be clarified and discussed.

Sincerely,
Huaisheng Ye
diff mbox

Patch

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 1a4582b..9e4d867 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -39,6 +39,9 @@ 
 #define ___GFP_DIRECT_RECLAIM	0x400000u
 #define ___GFP_WRITE		0x800000u
 #define ___GFP_KSWAPD_RECLAIM	0x1000000u
+#ifdef CONFIG_ZONE_NVM
+#define ___GFP_NVM		0x4000000u
+#endif
 #ifdef CONFIG_LOCKDEP
 #define ___GFP_NOLOCKDEP	0x2000000u
 #else
@@ -57,7 +60,12 @@ 
 #define __GFP_HIGHMEM	((__force gfp_t)___GFP_HIGHMEM)
 #define __GFP_DMA32	((__force gfp_t)___GFP_DMA32)
 #define __GFP_MOVABLE	((__force gfp_t)___GFP_MOVABLE)  /* ZONE_MOVABLE allowed */
+#ifdef CONFIG_ZONE_NVM
+#define __GFP_NVM	((__force gfp_t)___GFP_NVM)  /* ZONE_NVM allowed */
+#define GFP_ZONEMASK	(__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE|__GFP_NVM)
+#else
 #define GFP_ZONEMASK	(__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE)
+#endif
 
 /*
  * Page mobility and placement hints
@@ -205,7 +213,8 @@ 
 #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
 
 /* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP) + \
+				(IS_ENABLED(CONFIG_ZONE_NVM) << 1))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /*
@@ -283,6 +292,9 @@ 
 #define GFP_TRANSHUGE_LIGHT	((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
 			 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
 #define GFP_TRANSHUGE	(GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
+#ifdef CONFIG_ZONE_NVM
+#define GFP_NVM		__GFP_NVM
+#endif
 
 /* Convert GFP flags to their corresponding migrate type */
 #define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
@@ -342,7 +354,7 @@  static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
  *       0x0    => NORMAL
  *       0x1    => DMA or NORMAL
  *       0x2    => HIGHMEM or NORMAL
- *       0x3    => BAD (DMA+HIGHMEM)
+ *       0x3    => NVM (DMA+HIGHMEM), now it is used by NVDIMM zone
  *       0x4    => DMA32 or DMA or NORMAL
  *       0x5    => BAD (DMA+DMA32)
  *       0x6    => BAD (HIGHMEM+DMA32)
@@ -370,6 +382,29 @@  static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
 #error GFP_ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
 #endif
 
+#ifdef CONFIG_ZONE_NVM
+#define ___GFP_NVM_BIT (___GFP_DMA | ___GFP_HIGHMEM)
+#define GFP_ZONE_TABLE ( \
+	((__force unsigned long)ZONE_NORMAL <<				       \
+			0 * GFP_ZONES_SHIFT)				       \
+	| ((__force unsigned long)OPT_ZONE_DMA <<			       \
+			___GFP_DMA * GFP_ZONES_SHIFT)			       \
+	| ((__force unsigned long)OPT_ZONE_HIGHMEM <<			       \
+			___GFP_HIGHMEM * GFP_ZONES_SHIFT)		       \
+	| ((__force unsigned long)OPT_ZONE_DMA32 <<			       \
+			___GFP_DMA32 * GFP_ZONES_SHIFT)			       \
+	| ((__force unsigned long)ZONE_NORMAL <<			       \
+			___GFP_MOVABLE * GFP_ZONES_SHIFT)		       \
+	| ((__force unsigned long)OPT_ZONE_DMA <<			       \
+			(___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT)       \
+	| ((__force unsigned long)ZONE_MOVABLE <<			       \
+			(___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)   \
+	| ((__force unsigned long)OPT_ZONE_DMA32 <<			       \
+			(___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)     \
+	| ((__force unsigned long)ZONE_NVM <<				       \
+			___GFP_NVM_BIT * GFP_ZONES_SHIFT)                      \
+)
+#else
 #define GFP_ZONE_TABLE ( \
 	(ZONE_NORMAL << 0 * GFP_ZONES_SHIFT)				       \
 	| (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT)		       \
@@ -380,6 +415,7 @@  static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
 	| (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\
 	| (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\
 )
+#endif
 
 /*
  * GFP_ZONE_BAD is a bitmap for all combinations of __GFP_DMA, __GFP_DMA32
@@ -387,6 +423,17 @@  static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
  * entry starting with bit 0. Bit is set if the combination is not
  * allowed.
  */
+#ifdef CONFIG_ZONE_NVM
+#define GFP_ZONE_BAD ( \
+	1 << (___GFP_DMA | ___GFP_DMA32)				      \
+	| 1 << (___GFP_DMA32 | ___GFP_HIGHMEM)				      \
+	| 1 << (___GFP_DMA | ___GFP_DMA32 | ___GFP_HIGHMEM)		      \
+	| 1 << (___GFP_MOVABLE | ___GFP_HIGHMEM | ___GFP_DMA)		      \
+	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA)		      \
+	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_HIGHMEM)		      \
+	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA | ___GFP_HIGHMEM)  \
+)
+#else
 #define GFP_ZONE_BAD ( \
 	1 << (___GFP_DMA | ___GFP_HIGHMEM)				      \
 	| 1 << (___GFP_DMA | ___GFP_DMA32)				      \
@@ -397,12 +444,16 @@  static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
 	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_HIGHMEM)		      \
 	| 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA | ___GFP_HIGHMEM)  \
 )
+#endif
 
 static inline enum zone_type gfp_zone(gfp_t flags)
 {
 	enum zone_type z;
 	int bit = (__force int) (flags & GFP_ZONEMASK);
-
+#ifdef CONFIG_ZONE_NVM
+	if (bit & __GFP_NVM)
+		bit = (__force int)___GFP_NVM_BIT;
+#endif
 	z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
 					 ((1 << GFP_ZONES_SHIFT) - 1);
 	VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7522a69..f38e4a0 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -345,6 +345,9 @@  enum zone_type {
 	 */
 	ZONE_HIGHMEM,
 #endif
+#ifdef CONFIG_ZONE_NVM
+	ZONE_NVM,
+#endif
 	ZONE_MOVABLE,
 #ifdef CONFIG_ZONE_DEVICE
 	ZONE_DEVICE,
diff --git a/mm/Kconfig b/mm/Kconfig
index c782e8f..5fe1f63 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -687,6 +687,22 @@  config ZONE_DEVICE
 
 	  If FS_DAX is enabled, then say Y.
 
+config ZONE_NVM
+	bool "Manage NVDIMM (pmem) by memory management (EXPERIMENTAL)"
+	depends on NUMA && X86_64
+	depends on HAVE_MEMBLOCK_NODE_MAP
+	depends on HAVE_MEMBLOCK
+	depends on !IA32_EMULATION
+	default n
+
+	help
+	  This option allows you to use memory management subsystem to manage
+	  NVDIMM (pmem). With it mm can arrange NVDIMMs into real physical zones
+	  like NORMAL and DMA32. That means buddy system and swap can be used
+	  directly to NVDIMM zone. This feature is beneficial to recover
+	  dirty pages from power fail or system crash by storing write cache
+	  to NVDIMM zone.
+
 config ARCH_HAS_HMM
 	bool
 	default y
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 266c065..d8bd20d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -228,6 +228,9 @@  bool pm_suspended_storage(void)
 	 "DMA32",
 #endif
 	 "Normal",
+#ifdef CONFIG_ZONE_NVM
+	 "NVM",
+#endif
 #ifdef CONFIG_HIGHMEM
 	 "HighMem",
 #endif