[PATCH v1 6/9] x86, mm, numa, acpi: Support getting hotplug info from SRAT.

Tang Chen
2013-03-16T11:12:01Z

We now provide an option for users who don't want to specify physical
memory address in kernel commandline.

/*
* For movablemem_map=acpi:
*
* SRAT: |_____| |_____| |_________| |_________| ......
* node id: 0 1 1 2
* hotpluggable: n y y n
* movablemem_map: |_____| |_________|
*
* Using movablemem_map, we can prevent memblock from allocating memory
* on ZONE_MOVABLE at boot time.
*/

So user just specify movablemem_map=acpi, and the kernel will use hotpluggable
info in SRAT to determine which memory ranges should be set as ZONE_MOVABLE.

NOTE: Using this way will cause NUMA performance down because the whole node
will be set as ZONE_MOVABLE, and kernel cannot use memory on it.
If users don't want to lose NUMA performance, just don't use it.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
Documentation/kernel-parameters.txt | 15 +++++++
arch/x86/mm/srat.c | 74 +++++++++++++++++++++++++++++++++--
include/linux/mm.h | 2 +
mm/page_alloc.c | 22 ++++++++++-
4 files changed, 108 insertions(+), 5 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index dd3a36a..40387a2 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1649,6 +1649,17 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
that the amount of memory usable for all allocations
is not too small.

+ movablemem_map=acpi
+ [KNL,X86,IA-64,PPC] This parameter is similar to
+ memmap except it specifies the memory map of
+ ZONE_MOVABLE.
+ This option inform the kernel to use Hot Pluggable bit
+ in flags from SRAT from ACPI BIOS to determine which
+ memory devices could be hotplugged. The corresponding
+ memory ranges will be set as ZONE_MOVABLE.
+ NOTE: Whatever node the kernel resides in will always
+ be un-hotpluggable.
+
movablemem_map=nn[KMG]@ss[KMG]
[KNL,X86,IA-64,PPC] This parameter is similar to
memmap except it specifies the memory map of
@@ -1669,6 +1680,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
satisfied. So the administrator should be careful that
the amount of movablemem_map areas are not too large.
Otherwise kernel won't have enough memory to start.
+ NOTE: We don't stop users specifying the node the
+ kernel resides in as hotpluggable so that this
+ option can be used as a workaround of firmware
+ bugs.

MTD_Partition= [MTD]
Format: <name>,<region-number>,<size>,<offset>
diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
index ee888a2..fd3d4c8 100644
--- a/arch/x86/mm/srat.c
+++ b/arch/x86/mm/srat.c
@@ -142,15 +142,78 @@ static inline int save_add_info(void) {return 0;}
#endif

#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
-static void __init sanitize_movablemem_map(int nid, u64 start, u64 end)
+static void __init sanitize_movablemem_map(int nid, u64 start, u64 end,
+ bool hotpluggable)
{
- int overlap;
+ int overlap, i;
unsigned long start_pfn, end_pfn;

start_pfn = PFN_DOWN(start);
end_pfn = PFN_UP(end);

/*
+ * For movablemem_map=acpi:
+ *
+ * SRAT: |_____| |_____| |_________| |_________| ......
+ * node id: 0 1 1 2
+ * hotpluggable: n y y n
+ * movablemem_map: |_____| |_________|
+ *
+ * Using movablemem_map, we can prevent memblock from allocating memory
+ * on ZONE_MOVABLE at boot time.
+ *
+ * Before parsing SRAT, memblock has already reserve some memory ranges
+ * for other purposes, such as for kernel image. We cannot prevent
+ * kernel from using these memory, so we need to exclude these memory
+ * even if it is hotpluggable.
+ * Furthermore, to ensure the kernel has enough memory to boot, we make
+ * all the memory on the node which the kernel resides in should be
+ * un-hotpluggable.
+ */
+ if (hotpluggable && movablemem_map.acpi) {
+ /* Exclude ranges reserved by memblock. */
+ struct memblock_type *rgn = &memblock.reserved;
+
+ for (i = 0; i < rgn->cnt; i++) {
+ if (end <= rgn->regions[i].base ||
+ start >= rgn->regions[i].base +
+ rgn->regions[i].size)
+ continue;
+
+ /*
+ * If the memory range overlaps the memory reserved by
+ * memblock, then the kernel resides in this node.
+ */
+ node_set(nid, movablemem_map.numa_nodes_kernel);
+ zone_movable_limit[nid] = 0;
+
+ return;
+ }
+
+ /*
+ * If the kernel resides in this node, then the whole node
+ * should not be hotpluggable.
+ */
+ if (node_isset(nid, movablemem_map.numa_nodes_kernel)) {
+ zone_movable_limit[nid] = 0;
+ return;
+ }
+
+ /*
+ * Otherwise, if the range is hotpluggable, and the kernel is
+ * not on this node, insert it into movablemem_map.
+ */
+ insert_movablemem_map(start_pfn, end_pfn);
+ if (zone_movable_limit[nid])
+ zone_movable_limit[nid] = min(zone_movable_limit[nid],
+ start_pfn);
+ else
+ zone_movable_limit[nid] = start_pfn;
+
+ return;
+ }
+
+ /*
* For movablecore_map=nn[KMG]@ss[KMG]:
*
* SRAT: |_____| |_____| |_________| |_________| ......
@@ -160,6 +223,8 @@ static void __init sanitize_movablemem_map(int nid, u64 start, u64 end)
*
* Using movablemem_map, we can prevent memblock from allocating memory
* on ZONE_MOVABLE at boot time.
+ *
+ * NOTE: In this case, SRAT info will be ingored.
*/
overlap = movablemem_map_overlap(start_pfn, end_pfn);
if (overlap >= 0) {
@@ -189,7 +254,8 @@ static void __init sanitize_movablemem_map(int nid, u64 start, u64 end)
}
}
#else /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
-static inline void sanitize_movablemem_map(int nid, u64 start, u64 end)
+static inline void sanitize_movablemem_map(int nid, u64 start, u64 end,
+ bool hotpluggable)
{
}
#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
@@ -234,7 +300,7 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
(unsigned long long) start, (unsigned long long) end - 1,
hotpluggable ? "Hot Pluggable" : "");

- sanitize_movablemem_map(node, start, end);
+ sanitize_movablemem_map(node, start, end, hotpluggable);

return 0;
out_err_bad_srat:
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d2c5fec..37cf1d7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1339,8 +1339,10 @@ struct movablemem_entry {
};

struct movablemem_map {
+ bool acpi; /* True if using SRAT info. */
int nr_map;
struct movablemem_entry map[MOVABLEMEM_MAP_MAX];
+ nodemask_t numa_nodes_kernel; /* on which nodes kernel resides in */
};

extern struct movablemem_map movablemem_map;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f451ded..31d27af 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -203,7 +203,10 @@ static unsigned long __meminitdata dma_reserve;

#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
/* Movable memory ranges, will also be used by memblock subsystem. */
-struct movablemem_map movablemem_map;
+struct movablemem_map movablemem_map = {
+ .acpi = false,
+ .nr_map = 0,
+};

static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
@@ -5204,6 +5207,23 @@ static int __init cmdline_parse_movablemem_map(char *p)
if (!p)
goto err;

+ if (!strcmp(p, "acpi"))
+ movablemem_map.acpi = true;
+
+ /*
+ * If user decide to use info from BIOS, all the other user specified
+ * ranges will be ingored.
+ */
+ if (movablemem_map.acpi) {
+ if (movablemem_map.nr_map) {
+ memset(movablemem_map.map, 0,
+ sizeof(struct movablemem_entry) *
+ movablemem_map.nr_map);
+ movablemem_map.nr_map = 0;
+ }
+ return 0;
+ }
+
oldp = p;
mem_size = memparse(p, &p);
if (p == oldp)
--
1.7.1