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.t...@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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