[PATCH V5 2/3] mm/memblock: Add support for excluded memory areas

Philipp Hachtmann
2014-01-20T11:33:07Z

Add a new memory state "nomap" to memblock. This can be used to truncate
the usable memory in the system without forgetting about what is really
installed.

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
---
include/linux/memblock.h | 25 +++++++
mm/Kconfig | 3 +
mm/memblock.c | 175 ++++++++++++++++++++++++++++++++++++++++++++++-
mm/nobootmem.c | 8 ++-
4 files changed, 209 insertions(+), 2 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 1ef6636..be1c819 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -18,6 +18,7 @@
#include <linux/mm.h>

#define INIT_MEMBLOCK_REGIONS 128
+#define INIT_MEMBLOCK_NOMAP_REGIONS 4

/* Definition of memblock flags. */
#define MEMBLOCK_HOTPLUG 0x1 /* hotpluggable region */
@@ -43,6 +44,9 @@ struct memblock {
phys_addr_t current_limit;
struct memblock_type memory;
struct memblock_type reserved;
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+ struct memblock_type nomap;
+#endif
};

extern struct memblock memblock;
@@ -68,6 +72,10 @@ int memblock_add(phys_addr_t base, phys_addr_t size);
int memblock_remove(phys_addr_t base, phys_addr_t size);
int memblock_free(phys_addr_t base, phys_addr_t size);
int memblock_reserve(phys_addr_t base, phys_addr_t size);
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+int memblock_nomap(phys_addr_t base, phys_addr_t size);
+int memblock_remap(phys_addr_t base, phys_addr_t size);
+#endif
void memblock_trim_memory(phys_addr_t align);
int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
@@ -133,6 +141,23 @@ void __next_free_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
i != (u64)ULLONG_MAX; \
__next_free_mem_range(&i, nid, p_start, p_end, p_nid))

+
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+#define for_each_mapped_mem_range(i, nid, p_start, p_end, p_nid) \
+ for (i = 0, \
+ __next_mapped_mem_range(&i, nid, &memblock.memory, \
+ &memblock.nomap, p_start, \
+ p_end, p_nid); \
+ i != (u64)ULLONG_MAX; \
+ __next_mapped_mem_range(&i, nid, &memblock.memory, \
+ &memblock.nomap, \
+ p_start, p_end, p_nid))
+
+void __next_mapped_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
+ phys_addr_t *out_end, int *out_nid);
+
+#endif
+
void __next_free_mem_range_rev(u64 *idx, int nid, phys_addr_t *out_start,
phys_addr_t *out_end, int *out_nid);

diff --git a/mm/Kconfig b/mm/Kconfig
index 2d9f150..6907654 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -137,6 +137,9 @@ config HAVE_MEMBLOCK_NODE_MAP
config ARCH_DISCARD_MEMBLOCK
boolean

+config ARCH_MEMBLOCK_NOMAP
+ boolean
+
config NO_BOOTMEM
boolean

diff --git a/mm/memblock.c b/mm/memblock.c
index 9c0aeef..b36f5d3 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -28,6 +28,11 @@
static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;

+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+static struct memblock_region
+memblock_nomap_init_regions[INIT_MEMBLOCK_NOMAP_REGIONS] __initdata_memblock;
+#endif
+
struct memblock memblock __initdata_memblock = {
.memory.regions = memblock_memory_init_regions,
.memory.cnt = 1, /* empty dummy entry */
@@ -37,6 +42,11 @@ struct memblock memblock __initdata_memblock = {
.reserved.cnt = 1, /* empty dummy entry */
.reserved.max = INIT_MEMBLOCK_REGIONS,

+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+ .nomap.regions = memblock_nomap_init_regions,
+ .nomap.cnt = 1, /* empty dummy entry */
+ .nomap.max = INIT_MEMBLOCK_NOMAP_REGIONS,
+#endif
.bottom_up = false,
.current_limit = MEMBLOCK_ALLOC_ANYWHERE,
};
@@ -292,6 +302,20 @@ phys_addr_t __init_memblock get_allocated_memblock_memory_regions_info(
memblock.memory.max);
}

+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+phys_addr_t __init_memblock get_allocated_memblock_nomap_regions_info(
+ phys_addr_t *addr)
+{
+ if (memblock.memory.regions == memblock_memory_init_regions)
+ return 0;
+
+ *addr = __pa(memblock.memory.regions);
+
+ return PAGE_ALIGN(sizeof(struct memblock_region) *
+ memblock.memory.max);
+}
+
+#endif /* CONFIG_ARCH_MEMBLOCK_NOMAP */
#endif

/**
@@ -757,6 +781,60 @@ int __init_memblock memblock_clear_hotplug(phys_addr_t base, phys_addr_t size)
return 0;
}

+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+/*
+ * memblock_nomap() - mark a memory range as completely unusable
+ *
+ * This can be used to exclude memory regions from every further treatment
+ * in the running system. Ranges which are added to the nomap list will
+ * also be marked as reserved. So they won't either be allocated by memblock
+ * nor freed to the page allocator.
+ *
+ * The usable (i.e. not in nomap list) memory can be iterated
+ * via for_each_mapped_mem_range().
+ *
+ * memblock_start_of_DRAM() and memblock_end_of_DRAM() still refer to the
+ * whole system memory.
+ */
+int __init_memblock memblock_nomap(phys_addr_t base, phys_addr_t size)
+{
+ int ret;
+ memblock_dbg("memblock_nomap: [%#016llx-%#016llx] %pF\n",
+ (unsigned long long)base,
+ (unsigned long long)base + size,
+ (void *)_RET_IP_);
+
+ ret = memblock_add_region(&memblock.reserved, base,
+ size, MAX_NUMNODES, 0);
+ if (ret)
+ return ret;
+
+ return memblock_add_region(&memblock.nomap, base,
+ size, MAX_NUMNODES, 0);
+}
+
+/*
+ * memblock_remap() - remove a memory range from the nomap list
+ *
+ * This is the inverse function to memblock_nomap().
+ */
+int __init_memblock memblock_remap(phys_addr_t base, phys_addr_t size)
+{
+ int ret;
+ memblock_dbg("memblock_remap: [%#016llx-%#016llx] %pF\n",
+ (unsigned long long)base,
+ (unsigned long long)base + size,
+ (void *)_RET_IP_);
+
+ ret = __memblock_remove(&memblock.reserved, base, size);
+ if (ret)
+ return ret;
+
+ return __memblock_remove(&memblock.nomap, base, size);
+}
+
+#endif
+
/**
* __next_free_mem_range - next function for for_each_free_mem_range()
* @idx: pointer to u64 loop variable
@@ -836,6 +914,88 @@ void __init_memblock __next_free_mem_range(u64 *idx, int nid,
*idx = ULLONG_MAX;
}

+#ifdef ARCH_MEMBLOCK_NOMAP
+/**
+ * __next_mapped_mem_range - next function for for_each_free_mem_range()
+ * @idx: pointer to u64 loop variable
+ * @nid: node selector, %NUMA_NO_NODE for all nodes
+ * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ * @out_nid: ptr to int for nid of the range, can be %NULL
+ *
+ * Find the first free area from *@idx which matches @nid, fill the out
+ * parameters, and update *@idx for the next iteration. The lower 32bit of
+ * *@idx contains index into memory region and the upper 32bit indexes the
+ * areas before each reserved region. For example, if reserved regions
+ * look like the following,
+ *
+ * 0:[0-16), 1:[32-48), 2:[128-130)
+ *
+ * The upper 32bit indexes the following regions.
+ *
+ * 0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
+ *
+ * As both region arrays are sorted, the function advances the two indices
+ * in lockstep and returns each intersection.
+ */
+void __init_memblock __next_mapped_mem_range(u64 *idx, int nid,
+ phys_addr_t *out_start,
+ phys_addr_t *out_end, int *out_nid)
+{
+ struct memblock_type *mem = &memblock.memory;
+ struct memblock_type *rsv = &memblock.nomap;
+ int mi = *idx & 0xffffffff;
+ int ri = *idx >> 32;
+
+ if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
+ nid = NUMA_NO_NODE;
+
+ for (; mi < mem->cnt; mi++) {
+ struct memblock_region *m = &mem->regions[mi];
+ phys_addr_t m_start = m->base;
+ phys_addr_t m_end = m->base + m->size;
+
+ /* only memory regions are associated with nodes, check it */
+ if (nid != NUMA_NO_NODE && nid != memblock_get_region_node(m))
+ continue;
+
+ /* scan areas before each reservation for intersection */
+ for (; ri < rsv->cnt + 1; ri++) {
+ struct memblock_region *r = &rsv->regions[ri];
+ phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
+ phys_addr_t r_end = ri < rsv->cnt ?
+ r->base : ULLONG_MAX;
+
+ /* if ri advanced past mi, break out to advance mi */
+ if (r_start >= m_end)
+ break;
+ /* if the two regions intersect, we're done */
+ if (m_start < r_end) {
+ if (out_start)
+ *out_start = max(m_start, r_start);
+ if (out_end)
+ *out_end = min(m_end, r_end);
+ if (out_nid)
+ *out_nid = memblock_get_region_node(m);
+ /*
+ * The region which ends first is advanced
+ * for the next iteration.
+ */
+ if (m_end <= r_end)
+ mi++;
+ else
+ ri++;
+ *idx = (u32)mi | (u64)ri << 32;
+ return;
+ }
+ }
+ }
+
+ /* signal end of iteration */
+ *idx = ULLONG_MAX;
+}
+#endif
+
/**
* __next_free_mem_range_rev - next function for for_each_free_mem_range_reverse()
* @idx: pointer to u64 loop variable
@@ -1438,12 +1598,21 @@ static void __init_memblock memblock_dump(struct memblock_type *type, char *name
void __init_memblock __memblock_dump_all(void)
{
pr_info("MEMBLOCK configuration:\n");
+#ifndef CONFIG_ARCH_MEMBLOCK_NOMAP
pr_info(" memory size = %#llx reserved size = %#llx\n",
(unsigned long long)memblock.memory.total_size,
(unsigned long long)memblock.reserved.total_size);
-
+#else
+ pr_info(" memory size = %#llx reserved size = %#llx nomap size = %#llx\n",
+ (unsigned long long)memblock.memory.total_size,
+ (unsigned long long)memblock.reserved.total_size,
+ (unsigned long long)memblock.nomap.total_size);
+#endif
memblock_dump(&memblock.memory, "memory");
memblock_dump(&memblock.reserved, "reserved");
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+ memblock_dump(&memblock.nomap, "nomap");
+#endif
}

void __init memblock_allow_resize(void)
@@ -1502,6 +1671,10 @@ static int __init memblock_init_debugfs(void)
return -ENXIO;
debugfs_create_file("memory", S_IRUGO, root, &memblock.memory, &memblock_debug_fops);
debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved, &memblock_debug_fops);
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+ debugfs_create_file("nomap", S_IRUGO, root,
+ &memblock.nomap, &memblock_debug_fops);
+#endif

return 0;
}
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 0215c77..61966b6 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -138,9 +138,15 @@ static unsigned long __init free_low_memory_core_early(void)
size = get_allocated_memblock_memory_regions_info(&start);
if (size)
count += __free_memory_core(start, start + size);
+
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+ /* Free memblock.nomap array if it was allocated */
+ size = get_allocated_memblock_memory_regions_info(&start);
+ if (size)
+ count += __free_memory_core(start, start + size);
+#endif
}
#endif
-
return count;
}

--
1.8.4.5