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Subject[PATCH v1 1/2] mm/memblock: expose only miminal interface to add/walk physmem
Date
"physmem" in the memblock allocator is somewhat weird: it's not actually
used for allocation, it's simply information collected during boot, which
describes the unmodified physical memory map at boot time, without any
standby/hotplugged memory. It's only used on s390x and is currently the
only reason s390x keeps using CONFIG_ARCH_KEEP_MEMBLOCK.

Physmem isn't numa aware and current users don't specify any flags. Let's
hide it from the user, exposing only for_each_physmem(), and simplify. The
interface for physmem is now really minimalistic:
- memblock_physmem_add() to add ranges
- for_each_physmem() / __next_physmem_range() to walk physmem ranges

Don't place it into an __init section and don't discard it without
CONFIG_ARCH_KEEP_MEMBLOCK. As we're reusing __next_mem_range(), remove
the __meminit notifier to avoid section mismatch warnings once
CONFIG_ARCH_KEEP_MEMBLOCK is no longer used with
CONFIG_HAVE_MEMBLOCK_PHYS_MAP.

We can stop setting CONFIG_HAVE_MEMBLOCK_PHYS_MAP for s390x next.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/s390/kernel/crash_dump.c | 6 ++--
include/linux/memblock.h | 17 +++++++---
mm/memblock.c | 63 +++++++++++++++++++----------------
3 files changed, 50 insertions(+), 36 deletions(-)

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index f96a5857bbfde..c42ce348103cc 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -549,8 +549,7 @@ static int get_mem_chunk_cnt(void)
int cnt = 0;
u64 idx;

- for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
- MEMBLOCK_NONE, NULL, NULL, NULL)
+ for_each_physmem_range(idx, &oldmem_type, NULL, NULL)
cnt++;
return cnt;
}
@@ -563,8 +562,7 @@ static void loads_init(Elf64_Phdr *phdr, u64 loads_offset)
phys_addr_t start, end;
u64 idx;

- for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
- MEMBLOCK_NONE, &start, &end, NULL) {
+ for_each_physmem_range(idx, &oldmem_type, &start, &end) {
phdr->p_filesz = end - start;
phdr->p_type = PT_LOAD;
phdr->p_offset = start;
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 017fae833d4ae..10d879eda1ff7 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -77,16 +77,12 @@ struct memblock_type {
* @current_limit: physical address of the current allocation limit
* @memory: usable memory regions
* @reserved: reserved memory regions
- * @physmem: all physical memory
*/
struct memblock {
bool bottom_up; /* is bottom up direction? */
phys_addr_t current_limit;
struct memblock_type memory;
struct memblock_type reserved;
-#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
- struct memblock_type physmem;
-#endif
};

extern struct memblock memblock;
@@ -114,6 +110,19 @@ 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_HAVE_MEMBLOCK_PHYS_MAP
+/**
+ * for_each_physmem_range - iterate through physmem areas not included in type.
+ * @i: u64 used as loop variable
+ * @type: ptr to memblock_type which excludes from the iteration, can be %NULL
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ */
+#define for_each_physmem_range(i, type, p_start, p_end) \
+ for (i = 0, __next_physmem_range(&i, type, p_start, p_end); \
+ i != (u64)ULLONG_MAX; \
+ __next_physmem_range(&i, type, p_start, p_end))
+void __next_physmem_range(u64 *idx, struct memblock_type *type,
+ phys_addr_t *out_start, phys_addr_t *out_end);
int memblock_physmem_add(phys_addr_t base, phys_addr_t size);
#endif
void memblock_trim_memory(phys_addr_t align);
diff --git a/mm/memblock.c b/mm/memblock.c
index 39aceafc57f66..5f6389af11895 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -44,19 +44,19 @@
* in the system, for instance when the memory is restricted with
* ``mem=`` command line parameter
* * ``reserved`` - describes the regions that were allocated
- * * ``physmap`` - describes the actual physical memory regardless of
- * the possible restrictions; the ``physmap`` type is only available
- * on some architectures.
+ * * ``physmem`` - describes the actual physical memory available during
+ * boot regardless of the possible restrictions and memory hot(un)plug;
+ * the ``physmem`` type is only available on some architectures.
*
* Each region is represented by :c:type:`struct memblock_region` that
* defines the region extents, its attributes and NUMA node id on NUMA
* systems. Every memory type is described by the :c:type:`struct
* memblock_type` which contains an array of memory regions along with
- * the allocator metadata. The memory types are nicely wrapped with
- * :c:type:`struct memblock`. This structure is statically initialzed
- * at build time. The region arrays for the "memory" and "reserved"
- * types are initially sized to %INIT_MEMBLOCK_REGIONS and for the
- * "physmap" type to %INIT_PHYSMEM_REGIONS.
+ * the allocator metadata. The memory types (except "physmem") are nicely
+ * wrapped with :c:type:`struct memblock`. This structure is statically
+ * initialized at build time. The region arrays for the "memory" and
+ * "reserved" types are initially sized to %INIT_MEMBLOCK_REGIONS.
+ * The "physmem" type is sized to %INIT_PHYSMEM_REGIONS.
* The memblock_allow_resize() enables automatic resizing of the region
* arrays during addition of new regions. This feature should be used
* with care so that memory allocated for the region array will not
@@ -87,8 +87,8 @@
* function frees all the memory to the buddy page allocator.
*
* Unless an architecture enables %CONFIG_ARCH_KEEP_MEMBLOCK, the
- * memblock data structures will be discarded after the system
- * initialization completes.
+ * memblock data structures (except physmem) will be discarded after the
+ * system initialization completes.
*/

#ifndef CONFIG_NEED_MULTIPLE_NODES
@@ -104,7 +104,7 @@ unsigned long long max_possible_pfn;
static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_RESERVED_REGIONS] __initdata_memblock;
#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS] __initdata_memblock;
+static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS];
#endif

struct memblock memblock __initdata_memblock = {
@@ -118,17 +118,19 @@ struct memblock memblock __initdata_memblock = {
.reserved.max = INIT_MEMBLOCK_RESERVED_REGIONS,
.reserved.name = "reserved",

-#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
- .physmem.regions = memblock_physmem_init_regions,
- .physmem.cnt = 1, /* empty dummy entry */
- .physmem.max = INIT_PHYSMEM_REGIONS,
- .physmem.name = "physmem",
-#endif
-
.bottom_up = false,
.current_limit = MEMBLOCK_ALLOC_ANYWHERE,
};

+#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+struct memblock_type physmem = {
+ .regions = memblock_physmem_init_regions,
+ .cnt = 1, /* empty dummy entry */
+ .max = INIT_PHYSMEM_REGIONS,
+ .name = "physmem",
+};
+#endif
+
int memblock_debug __initdata_memblock;
static bool system_has_some_mirror __initdata_memblock = false;
static int memblock_can_resize __initdata_memblock;
@@ -831,6 +833,13 @@ int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
}

#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+void __next_physmem_range(u64 *idx, struct memblock_type *type,
+ phys_addr_t *out_start, phys_addr_t *out_end)
+{
+ __next_mem_range(idx, NUMA_NO_NODE, MEMBLOCK_NONE, &physmem, type,
+ out_start, out_end, NULL);
+}
+
int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
{
phys_addr_t end = base + size - 1;
@@ -838,7 +847,7 @@ int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
&base, &end, (void *)_RET_IP_);

- return memblock_add_range(&memblock.physmem, base, size, MAX_NUMNODES, 0);
+ return memblock_add_range(&physmem, base, size, MAX_NUMNODES, 0);
}
#endif

@@ -1019,12 +1028,10 @@ static bool should_skip_region(struct memblock_region *m, int nid, int flags)
* As both region arrays are sorted, the function advances the two indices
* in lockstep and returns each intersection.
*/
-void __init_memblock __next_mem_range(u64 *idx, int nid,
- enum memblock_flags flags,
- struct memblock_type *type_a,
- struct memblock_type *type_b,
- phys_addr_t *out_start,
- phys_addr_t *out_end, int *out_nid)
+void __next_mem_range(u64 *idx, int nid, enum memblock_flags flags,
+ struct memblock_type *type_a,
+ struct memblock_type *type_b, phys_addr_t *out_start,
+ phys_addr_t *out_end, int *out_nid)
{
int idx_a = *idx & 0xffffffff;
int idx_b = *idx >> 32;
@@ -1924,7 +1931,7 @@ void __init_memblock __memblock_dump_all(void)
memblock_dump(&memblock.memory);
memblock_dump(&memblock.reserved);
#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
- memblock_dump(&memblock.physmem);
+ memblock_dump(&physmem);
#endif
}

@@ -2064,8 +2071,8 @@ static int __init memblock_init_debugfs(void)
debugfs_create_file("reserved", 0444, root,
&memblock.reserved, &memblock_debug_fops);
#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
- debugfs_create_file("physmem", 0444, root,
- &memblock.physmem, &memblock_debug_fops);
+ debugfs_create_file("physmem", 0444, root, &physmem,
+ &memblock_debug_fops);
#endif

return 0;
--
2.26.2
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