[PATCH v2 2/2] mm: Introduce kernelcore=reliable option

Taku Izumi
2015-11-27T06:02:09Z

This patch extends existing "kernelcore" option and
introduces kernelcore=reliable option. By specifying
"reliable" instead of specifying the amount of memory,
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: |--------------------------|
|ooooooxxxxxxooooooxxxxxxxx| ZONE_NORMAL
|ooooooxxxxxxoooooooo| ZONE_MOVABLE
(legend) o: present x: absent

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
---
Documentation/kernel-parameters.txt | 9 ++-
mm/page_alloc.c | 110 ++++++++++++++++++++++++++++++++++--
2 files changed, 112 insertions(+), 7 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f8aae63..ed44c2c8 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] | "reliable"
+ [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 +1712,12 @@ 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 "reliable" option. In case "reliable"
+ option is specified, reliable memory is used for
+ non-movable allocations and remaining memory is used
+ for Movable pages.
+
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..006a3d8 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 reliable_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 reliable_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 (!reliable_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 (reliable_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 (reliable_kernelcore) {
+ unsigned long start_pfn, end_pfn;
+ struct memblock_region *r;
+
+ for_each_memblock(memory, r) {
+ start_pfn = clamp((ulong)PFN_DOWN(r->base),
+ zone_start_pfn, zone_end_pfn);
+ end_pfn = clamp((ulong)PFN_DOWN(r->base + r->size),
+ 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=reliable is specified, ignore movablecore option
+ */
+ if (reliable_kernelcore) {
+ bool mem_below_4gb_not_mirrored = false;
+
+ for_each_memblock(memory, r) {
+ if (memblock_is_mirror(r))
+ continue;
+
+ nid = r->nid;
+
+ usable_startpfn = PFN_DOWN(r->base);
+
+ 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=reliable */
+ if (parse_option_str(p, "reliable")) {
+ reliable_kernelcore = true;
+ return 0;
+ }
+
return cmdline_parse_core(p, &required_kernelcore);
}

--
1.8.3.1