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[PATCH v3 2/2] mm: Introduce kernelcore=mirror option

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  [PATCH v3 2/2] mm: Introduce kernelcore=mirror option Taku Izumi <izumi.taku@jp.fujitsu.com> - 2015-12-09 04:20 +0100
    Re: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option Xishi Qiu <qiuxishi@huawei.com> - 2015-12-09 04:30 +0100
      RE: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option "Luck, Tony" <tony.luck@intel.com> - 2015-12-09 23:00 +0100
        Re: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option Xishi Qiu <qiuxishi@huawei.com> - 2015-12-10 02:20 +0100
          RE: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option "Izumi, Taku" <izumi.taku@jp.fujitsu.com> - 2015-12-10 06:40 +0100
            Re: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option Xishi Qiu <qiuxishi@huawei.com> - 2015-12-10 07:20 +0100
              RE: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option "Izumi, Taku" <izumi.taku@jp.fujitsu.com> - 2015-12-11 07:00 +0100
                Re: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option Xishi Qiu <qiuxishi@huawei.com> - 2015-12-11 10:50 +0100

#1287047 — [PATCH v3 2/2] mm: Introduce kernelcore=mirror option

This patch extends existing "kernelcore" option and
introduces kernelcore=mirror option. By specifying
"mirror" instead of specifying the amount of memory,
non-mirrored (non-reliable) region will be arranged
into ZONE_MOVABLE.

v1 -> v2:
 - Refine so that the following case also can be
   handled properly:

 Node X:  |MMMMMM------MMMMMM--------|
   (legend) M: mirrored  -: not mirrrored

 In this case, ZONE_NORMAL and ZONE_MOVABLE are
 arranged like bellow:

 Node X:  |MMMMMM------MMMMMM--------|
          |ooooooxxxxxxooooooxxxxxxxx| ZONE_NORMAL
                |ooooooxxxxxxoooooooo| ZONE_MOVABLE
   (legend) o: present  x: absent

v2 -> v3:
 - change the option name from kernelcore=reliable
   into kernelcore=mirror
 - documentation fix so that users can understand
   nn[KMS] and mirror are exclusive

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
---
 Documentation/kernel-parameters.txt |  11 +++-
 mm/page_alloc.c                     | 110 ++++++++++++++++++++++++++++++++++--
 2 files changed, 114 insertions(+), 7 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f8aae63..b0ffc76 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1695,7 +1695,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
 	keepinitrd	[HW,ARM]
 
-	kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
+	kernelcore=	Format: nn[KMG] | "mirror"
+			[KNL,X86,IA-64,PPC] This parameter
 			specifies the amount of memory usable by the kernel
 			for non-movable allocations.  The requested amount is
 			spread evenly throughout all nodes in the system. The
@@ -1711,6 +1712,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			use the HighMem zone if it exists, and the Normal
 			zone if it does not.
 
+			Instead of specifying the amount of memory (nn[KMS]),
+			you can specify "mirror" option. In case "mirror"
+			option is specified, mirrored (reliable) memory is used
+			for non-movable allocations and remaining memory is used
+			for Movable pages. nn[KMS] and "mirror" are exclusive,
+			so you can NOT specify nn[KMG] and "mirror" at the same
+			time.
+
 	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
 			Format: <Controller#>[,poll interval]
 			The controller # is the number of the ehci usb debug
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index acb0b4e..4157476 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -251,6 +251,7 @@ static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
 static unsigned long __initdata required_kernelcore;
 static unsigned long __initdata required_movablecore;
 static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
+static bool mirrored_kernelcore;
 
 /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
 int movable_zone;
@@ -4472,6 +4473,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 	unsigned long pfn;
 	struct zone *z;
 	unsigned long nr_initialised = 0;
+	struct memblock_region *r = NULL, *tmp;
 
 	if (highest_memmap_pfn < end_pfn - 1)
 		highest_memmap_pfn = end_pfn - 1;
@@ -4491,6 +4493,38 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 			if (!update_defer_init(pgdat, pfn, end_pfn,
 						&nr_initialised))
 				break;
+
+			/*
+			 * if not mirrored_kernelcore and ZONE_MOVABLE exists,
+			 * range from zone_movable_pfn[nid] to end of each node
+			 * should be ZONE_MOVABLE not ZONE_NORMAL. skip it.
+			 */
+			if (!mirrored_kernelcore && zone_movable_pfn[nid])
+				if (zone == ZONE_NORMAL &&
+				    pfn >= zone_movable_pfn[nid])
+					continue;
+
+			/*
+			 * check given memblock attribute by firmware which
+			 * can affect kernel memory layout.
+			 * if zone==ZONE_MOVABLE but memory is mirrored,
+			 * it's an overlapped memmap init. skip it.
+			 */
+			if (mirrored_kernelcore && zone == ZONE_MOVABLE) {
+				if (!r ||
+				    pfn >= memblock_region_memory_end_pfn(r)) {
+					for_each_memblock(memory, tmp)
+						if (pfn < memblock_region_memory_end_pfn(tmp))
+							break;
+					r = tmp;
+				}
+				if (pfn >= memblock_region_memory_base_pfn(r) &&
+				    memblock_is_mirror(r)) {
+					/* already initialized as NORMAL */
+					pfn = memblock_region_memory_end_pfn(r);
+					continue;
+				}
+			}
 		}
 
 		/*
@@ -4909,11 +4943,6 @@ static void __meminit adjust_zone_range_for_zone_movable(int nid,
 			*zone_end_pfn = min(node_end_pfn,
 				arch_zone_highest_possible_pfn[movable_zone]);
 
-		/* Adjust for ZONE_MOVABLE starting within this range */
-		} else if (*zone_start_pfn < zone_movable_pfn[nid] &&
-				*zone_end_pfn > zone_movable_pfn[nid]) {
-			*zone_end_pfn = zone_movable_pfn[nid];
-
 		/* Check if this whole range is within ZONE_MOVABLE */
 		} else if (*zone_start_pfn >= zone_movable_pfn[nid])
 			*zone_start_pfn = *zone_end_pfn;
@@ -4998,6 +5027,7 @@ static unsigned long __meminit zone_absent_pages_in_node(int nid,
 	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
 	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
 	unsigned long zone_start_pfn, zone_end_pfn;
+	unsigned long nr_absent;
 
 	/* When hotadd a new node from cpu_up(), the node should be empty */
 	if (!node_start_pfn && !node_end_pfn)
@@ -5009,7 +5039,39 @@ static unsigned long __meminit zone_absent_pages_in_node(int nid,
 	adjust_zone_range_for_zone_movable(nid, zone_type,
 			node_start_pfn, node_end_pfn,
 			&zone_start_pfn, &zone_end_pfn);
-	return __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
+	nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
+
+	/*
+	 * ZONE_MOVABLE handling.
+	 * Treat pages to be ZONE_MOVABLE in ZONE_NORMAL as absent pages
+	 * and vice versa.
+	 */
+	if (zone_movable_pfn[nid]) {
+		if (mirrored_kernelcore) {
+			unsigned long start_pfn, end_pfn;
+			struct memblock_region *r;
+
+			for_each_memblock(memory, r) {
+				start_pfn = clamp(memblock_region_memory_base_pfn(r),
+						  zone_start_pfn, zone_end_pfn);
+				end_pfn = clamp(memblock_region_memory_end_pfn(r),
+						zone_start_pfn, zone_end_pfn);
+
+				if (zone_type == ZONE_MOVABLE &&
+				    memblock_is_mirror(r))
+					nr_absent += end_pfn - start_pfn;
+
+				if (zone_type == ZONE_NORMAL &&
+				    !memblock_is_mirror(r))
+					nr_absent += end_pfn - start_pfn;
+			}
+		} else {
+			if (zone_type == ZONE_NORMAL)
+				nr_absent += node_end_pfn - zone_movable_pfn[nid];
+		}
+	}
+
+	return nr_absent;
 }
 
 #else /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
@@ -5507,6 +5569,36 @@ static void __init find_zone_movable_pfns_for_nodes(void)
 	}
 
 	/*
+	 * If kernelcore=mirror is specified, ignore movablecore option
+	 */
+	if (mirrored_kernelcore) {
+		bool mem_below_4gb_not_mirrored = false;
+
+		for_each_memblock(memory, r) {
+			if (memblock_is_mirror(r))
+				continue;
+
+			nid = r->nid;
+
+			usable_startpfn = memblock_region_memory_base_pfn(r);
+
+			if (usable_startpfn < 0x100000) {
+				mem_below_4gb_not_mirrored = true;
+				continue;
+			}
+
+			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
+				min(usable_startpfn, zone_movable_pfn[nid]) :
+				usable_startpfn;
+		}
+
+		if (mem_below_4gb_not_mirrored)
+			pr_warn("This configuration results in unmirrored kernel memory.");
+
+		goto out2;
+	}
+
+	/*
 	 * If movablecore=nn[KMG] was specified, calculate what size of
 	 * kernelcore that corresponds so that memory usable for
 	 * any allocation type is evenly spread. If both kernelcore
@@ -5766,6 +5858,12 @@ static int __init cmdline_parse_core(char *p, unsigned long *core)
  */
 static int __init cmdline_parse_kernelcore(char *p)
 {
+	/* parse kernelcore=mirror */
+	if (parse_option_str(p, "mirror")) {
+		mirrored_kernelcore = true;
+		return 0;
+	}
+
 	return cmdline_parse_core(p, &required_kernelcore);
 }
 
-- 
1.9.1

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#1287057

On 2015/12/9 11:19, Taku Izumi wrote:

> This patch extends existing "kernelcore" option and
> introduces kernelcore=mirror option. By specifying
> "mirror" instead of specifying the amount of memory,
> non-mirrored (non-reliable) region will be arranged
> into ZONE_MOVABLE.
> 
> v1 -> v2:
>  - Refine so that the following case also can be
>    handled properly:
> 
>  Node X:  |MMMMMM------MMMMMM--------|
>    (legend) M: mirrored  -: not mirrrored
> 
>  In this case, ZONE_NORMAL and ZONE_MOVABLE are
>  arranged like bellow:
> 
>  Node X:  |MMMMMM------MMMMMM--------|
>           |ooooooxxxxxxooooooxxxxxxxx| ZONE_NORMAL
>                 |ooooooxxxxxxoooooooo| ZONE_MOVABLE
>    (legend) o: present  x: absent
> 
> v2 -> v3:
>  - change the option name from kernelcore=reliable
>    into kernelcore=mirror
>  - documentation fix so that users can understand
>    nn[KMS] and mirror are exclusive
> 
> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
> ---
>  Documentation/kernel-parameters.txt |  11 +++-
>  mm/page_alloc.c                     | 110 ++++++++++++++++++++++++++++++++++--
>  2 files changed, 114 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index f8aae63..b0ffc76 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1695,7 +1695,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  
>  	keepinitrd	[HW,ARM]
>  
> -	kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
> +	kernelcore=	Format: nn[KMG] | "mirror"
> +			[KNL,X86,IA-64,PPC] This parameter
>  			specifies the amount of memory usable by the kernel
>  			for non-movable allocations.  The requested amount is
>  			spread evenly throughout all nodes in the system. The
> @@ -1711,6 +1712,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			use the HighMem zone if it exists, and the Normal
>  			zone if it does not.
>  
> +			Instead of specifying the amount of memory (nn[KMS]),
> +			you can specify "mirror" option. In case "mirror"
> +			option is specified, mirrored (reliable) memory is used
> +			for non-movable allocations and remaining memory is used
> +			for Movable pages. nn[KMS] and "mirror" are exclusive,
> +			so you can NOT specify nn[KMG] and "mirror" at the same
> +			time.
> +

Hi Taku,

How about add some comment, if mirrored memroy is too small, then the
normal zone is small, so it may be oom.
The mirrored memory is at least 1/64 of whole memory, because struct
pages usually take 64 bytes per page.

Thanks,
Xishi Qiu

>  	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
>  			Format: <Controller#>[,poll interval]
>  			The controller # is the number of the ehci usb debug
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index acb0b4e..4157476 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -251,6 +251,7 @@ static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
>  static unsigned long __initdata required_kernelcore;
>  static unsigned long __initdata required_movablecore;
>  static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
> +static bool mirrored_kernelcore;
>  
>  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
>  int movable_zone;
> @@ -4472,6 +4473,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
>  	unsigned long pfn;
>  	struct zone *z;
>  	unsigned long nr_initialised = 0;
> +	struct memblock_region *r = NULL, *tmp;
>  
>  	if (highest_memmap_pfn < end_pfn - 1)
>  		highest_memmap_pfn = end_pfn - 1;
> @@ -4491,6 +4493,38 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
>  			if (!update_defer_init(pgdat, pfn, end_pfn,
>  						&nr_initialised))
>  				break;
> +
> +			/*
> +			 * if not mirrored_kernelcore and ZONE_MOVABLE exists,
> +			 * range from zone_movable_pfn[nid] to end of each node
> +			 * should be ZONE_MOVABLE not ZONE_NORMAL. skip it.
> +			 */
> +			if (!mirrored_kernelcore && zone_movable_pfn[nid])
> +				if (zone == ZONE_NORMAL &&
> +				    pfn >= zone_movable_pfn[nid])
> +					continue;
> +
> +			/*
> +			 * check given memblock attribute by firmware which
> +			 * can affect kernel memory layout.
> +			 * if zone==ZONE_MOVABLE but memory is mirrored,
> +			 * it's an overlapped memmap init. skip it.
> +			 */
> +			if (mirrored_kernelcore && zone == ZONE_MOVABLE) {
> +				if (!r ||
> +				    pfn >= memblock_region_memory_end_pfn(r)) {
> +					for_each_memblock(memory, tmp)
> +						if (pfn < memblock_region_memory_end_pfn(tmp))
> +							break;
> +					r = tmp;
> +				}
> +				if (pfn >= memblock_region_memory_base_pfn(r) &&
> +				    memblock_is_mirror(r)) {
> +					/* already initialized as NORMAL */
> +					pfn = memblock_region_memory_end_pfn(r);
> +					continue;
> +				}
> +			}
>  		}
>  
>  		/*
> @@ -4909,11 +4943,6 @@ static void __meminit adjust_zone_range_for_zone_movable(int nid,
>  			*zone_end_pfn = min(node_end_pfn,
>  				arch_zone_highest_possible_pfn[movable_zone]);
>  
> -		/* Adjust for ZONE_MOVABLE starting within this range */
> -		} else if (*zone_start_pfn < zone_movable_pfn[nid] &&
> -				*zone_end_pfn > zone_movable_pfn[nid]) {
> -			*zone_end_pfn = zone_movable_pfn[nid];
> -
>  		/* Check if this whole range is within ZONE_MOVABLE */
>  		} else if (*zone_start_pfn >= zone_movable_pfn[nid])
>  			*zone_start_pfn = *zone_end_pfn;
> @@ -4998,6 +5027,7 @@ static unsigned long __meminit zone_absent_pages_in_node(int nid,
>  	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
>  	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
>  	unsigned long zone_start_pfn, zone_end_pfn;
> +	unsigned long nr_absent;
>  
>  	/* When hotadd a new node from cpu_up(), the node should be empty */
>  	if (!node_start_pfn && !node_end_pfn)
> @@ -5009,7 +5039,39 @@ static unsigned long __meminit zone_absent_pages_in_node(int nid,
>  	adjust_zone_range_for_zone_movable(nid, zone_type,
>  			node_start_pfn, node_end_pfn,
>  			&zone_start_pfn, &zone_end_pfn);
> -	return __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
> +	nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
> +
> +	/*
> +	 * ZONE_MOVABLE handling.
> +	 * Treat pages to be ZONE_MOVABLE in ZONE_NORMAL as absent pages
> +	 * and vice versa.
> +	 */
> +	if (zone_movable_pfn[nid]) {
> +		if (mirrored_kernelcore) {
> +			unsigned long start_pfn, end_pfn;
> +			struct memblock_region *r;
> +
> +			for_each_memblock(memory, r) {
> +				start_pfn = clamp(memblock_region_memory_base_pfn(r),
> +						  zone_start_pfn, zone_end_pfn);
> +				end_pfn = clamp(memblock_region_memory_end_pfn(r),
> +						zone_start_pfn, zone_end_pfn);
> +
> +				if (zone_type == ZONE_MOVABLE &&
> +				    memblock_is_mirror(r))
> +					nr_absent += end_pfn - start_pfn;
> +
> +				if (zone_type == ZONE_NORMAL &&
> +				    !memblock_is_mirror(r))
> +					nr_absent += end_pfn - start_pfn;
> +			}
> +		} else {
> +			if (zone_type == ZONE_NORMAL)
> +				nr_absent += node_end_pfn - zone_movable_pfn[nid];
> +		}
> +	}
> +
> +	return nr_absent;
>  }
>  
>  #else /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
> @@ -5507,6 +5569,36 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  	}
>  
>  	/*
> +	 * If kernelcore=mirror is specified, ignore movablecore option
> +	 */
> +	if (mirrored_kernelcore) {
> +		bool mem_below_4gb_not_mirrored = false;
> +
> +		for_each_memblock(memory, r) {
> +			if (memblock_is_mirror(r))
> +				continue;
> +
> +			nid = r->nid;
> +
> +			usable_startpfn = memblock_region_memory_base_pfn(r);
> +
> +			if (usable_startpfn < 0x100000) {
> +				mem_below_4gb_not_mirrored = true;
> +				continue;
> +			}
> +
> +			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
> +				min(usable_startpfn, zone_movable_pfn[nid]) :
> +				usable_startpfn;
> +		}
> +
> +		if (mem_below_4gb_not_mirrored)
> +			pr_warn("This configuration results in unmirrored kernel memory.");
> +
> +		goto out2;
> +	}
> +
> +	/*
>  	 * If movablecore=nn[KMG] was specified, calculate what size of
>  	 * kernelcore that corresponds so that memory usable for
>  	 * any allocation type is evenly spread. If both kernelcore
> @@ -5766,6 +5858,12 @@ static int __init cmdline_parse_core(char *p, unsigned long *core)
>   */
>  static int __init cmdline_parse_kernelcore(char *p)
>  {
> +	/* parse kernelcore=mirror */
> +	if (parse_option_str(p, "mirror")) {
> +		mirrored_kernelcore = true;
> +		return 0;
> +	}
> +
>  	return cmdline_parse_core(p, &required_kernelcore);
>  }
>  



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#1287909

> How about add some comment, if mirrored memroy is too small, then the
> normal zone is small, so it may be oom.
> The mirrored memory is at least 1/64 of whole memory, because struct
> pages usually take 64 bytes per page.

1/64th is the absolute lower bound (for the page structures as you say). I
expect people will need to configure 10% or more to run any real workloads.

I made the memblock boot time allocator fall back to non-mirrored memory
if mirrored memory ran out.  What happens in the run time allocator if the
non-movable zones run out of pages? Will we allocate kernel pages from movable
memory?

-Tony
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#1288101

On 2015/12/10 5:59, Luck, Tony wrote:

>> How about add some comment, if mirrored memroy is too small, then the
>> normal zone is small, so it may be oom.
>> The mirrored memory is at least 1/64 of whole memory, because struct
>> pages usually take 64 bytes per page.
> 
> 1/64th is the absolute lower bound (for the page structures as you say). I
> expect people will need to configure 10% or more to run any real workloads.
> 
> I made the memblock boot time allocator fall back to non-mirrored memory
> if mirrored memory ran out.  What happens in the run time allocator if the
> non-movable zones run out of pages? Will we allocate kernel pages from movable
> memory?
> 

As I know, the kernel pages will not allocated from movable zone.

Thanks,
Xishi Qiu

> -Tony
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#1288208

Dear Tony, Xishi,

> >> How about add some comment, if mirrored memroy is too small, then the
> >> normal zone is small, so it may be oom.
> >> The mirrored memory is at least 1/64 of whole memory, because struct
> >> pages usually take 64 bytes per page.
> >
> > 1/64th is the absolute lower bound (for the page structures as you say). I
> > expect people will need to configure 10% or more to run any real workloads.

> >
> > I made the memblock boot time allocator fall back to non-mirrored memory
> > if mirrored memory ran out.  What happens in the run time allocator if the
> > non-movable zones run out of pages? Will we allocate kernel pages from movable
> > memory?
> >
> 
> As I know, the kernel pages will not allocated from movable zone.

 Yes, kernel pages are not allocated from ZONE_MOVABLE.

 In this case administrator must review and reconfigure the mirror ratio via 
 "MirrorRequest" EFI variable.
 
  Sincerely,
  Taku Izumi

>
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> >
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> 

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#1288223

On 2015/12/10 13:37, Izumi, Taku wrote:

> Dear Tony, Xishi,
> 
>>>> How about add some comment, if mirrored memroy is too small, then the
>>>> normal zone is small, so it may be oom.
>>>> The mirrored memory is at least 1/64 of whole memory, because struct
>>>> pages usually take 64 bytes per page.
>>>
>>> 1/64th is the absolute lower bound (for the page structures as you say). I
>>> expect people will need to configure 10% or more to run any real workloads.
> 
>>>
>>> I made the memblock boot time allocator fall back to non-mirrored memory
>>> if mirrored memory ran out.  What happens in the run time allocator if the
>>> non-movable zones run out of pages? Will we allocate kernel pages from movable
>>> memory?
>>>
>>
>> As I know, the kernel pages will not allocated from movable zone.
> 
>  Yes, kernel pages are not allocated from ZONE_MOVABLE.
> 
>  In this case administrator must review and reconfigure the mirror ratio via 
>  "MirrorRequest" EFI variable.
>  
>   Sincerely,
>   Taku Izumi
> 

Hi Taku,

Whether it is possible that we rewrite the fallback function in buddy system
when zone_movable and mirrored_kernelcore are both enabled?

It seems something like that we add a new zone but the name is zone_movable,
not zone_mirror. And the prerequisite is that we won't enable these two
features(movable memory and mirrored memory) at the same time. Thus we can
reuse the code of movable zone.

Thanks,
Xishi Qiu

>>
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>>>
>>> .
>>>
>>
>>
> 
> 
> .
> 



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#1289229

Dear Xishi,

> Hi Taku,
> 
> Whether it is possible that we rewrite the fallback function in buddy system
> when zone_movable and mirrored_kernelcore are both enabled?

  What does "when zone_movable and mirrored_kernelcore are both enabled?" mean ?
  
  My patchset just provides a new way to create ZONE_MOVABLE.

  Sincerely,
  Taku Izumi
> 
> It seems something like that we add a new zone but the name is zone_movable,
> not zone_mirror. And the prerequisite is that we won't enable these two
> features(movable memory and mirrored memory) at the same time. Thus we can
> reuse the code of movable zone.
> 

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#1289366

On 2015/12/11 13:53, Izumi, Taku wrote:

> Dear Xishi,
> 
>> Hi Taku,
>>
>> Whether it is possible that we rewrite the fallback function in buddy system
>> when zone_movable and mirrored_kernelcore are both enabled?
> 
>   What does "when zone_movable and mirrored_kernelcore are both enabled?" mean ?
>   
>   My patchset just provides a new way to create ZONE_MOVABLE.
> 

Hi Taku,

I mean when zone_movable is from kernelcore=mirror, not kernelcore=nn[KMG].

Thanks,
Xishi Qiu

>   Sincerely,
>   Taku Izumi
>>
>> It seems something like that we add a new zone but the name is zone_movable,
>> not zone_mirror. And the prerequisite is that we won't enable these two
>> features(movable memory and mirrored memory) at the same time. Thus we can
>> reuse the code of movable zone.
>>
> 
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