[PATCH v7 01/18] memblock: add MEMBLOCK_RSRV_KERN flag

Changyuan Lyu
2025-05-01T22:55:10Z

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

to denote areas that were reserved for kernel use either directly with
memblock_reserve_kern() or via memblock allocations.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
---
include/linux/memblock.h | 19 ++++++++-
mm/memblock.c | 40 +++++++++++++++----
tools/testing/memblock/tests/alloc_api.c | 22 +++++-----
.../memblock/tests/alloc_helpers_api.c | 4 +-
tools/testing/memblock/tests/alloc_nid_api.c | 20 +++++-----
5 files changed, 73 insertions(+), 32 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index ef5a1ecc6e595..6c00fbc085132 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -42,6 +42,9 @@ extern unsigned long long max_possible_pfn;
* kernel resource tree.
* @MEMBLOCK_RSRV_NOINIT: memory region for which struct pages are
* not initialized (only for reserved regions).
+ * @MEMBLOCK_RSRV_KERN: memory region that is reserved for kernel use,
+ * either explictitly with memblock_reserve_kern() or via memblock
+ * allocation APIs. All memblock allocations set this flag.
*/
enum memblock_flags {
MEMBLOCK_NONE = 0x0, /* No special request */
@@ -50,6 +53,7 @@ enum memblock_flags {
MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct mapping */
MEMBLOCK_DRIVER_MANAGED = 0x8, /* always detected via a driver */
MEMBLOCK_RSRV_NOINIT = 0x10, /* don't initialize struct pages */
+ MEMBLOCK_RSRV_KERN = 0x20, /* memory reserved for kernel use */
};

/**
@@ -116,7 +120,19 @@ int memblock_add_node(phys_addr_t base, phys_addr_t size, int nid,
int memblock_add(phys_addr_t base, phys_addr_t size);
int memblock_remove(phys_addr_t base, phys_addr_t size);
int memblock_phys_free(phys_addr_t base, phys_addr_t size);
-int memblock_reserve(phys_addr_t base, phys_addr_t size);
+int __memblock_reserve(phys_addr_t base, phys_addr_t size, int nid,
+ enum memblock_flags flags);
+
+static __always_inline int memblock_reserve(phys_addr_t base, phys_addr_t size)
+{
+ return __memblock_reserve(base, size, NUMA_NO_NODE, 0);
+}
+
+static __always_inline int memblock_reserve_kern(phys_addr_t base, phys_addr_t size)
+{
+ return __memblock_reserve(base, size, NUMA_NO_NODE, MEMBLOCK_RSRV_KERN);
+}
+
#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
int memblock_physmem_add(phys_addr_t base, phys_addr_t size);
#endif
@@ -476,6 +492,7 @@ static inline __init_memblock bool memblock_bottom_up(void)

phys_addr_t memblock_phys_mem_size(void);
phys_addr_t memblock_reserved_size(void);
+phys_addr_t memblock_reserved_kern_size(phys_addr_t limit, int nid);
unsigned long memblock_estimated_nr_free_pages(void);
phys_addr_t memblock_start_of_DRAM(void);
phys_addr_t memblock_end_of_DRAM(void);
diff --git a/mm/memblock.c b/mm/memblock.c
index 0a53db4d9f7be..2dc95ecdee5ce 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -492,7 +492,7 @@ static int __init_memblock memblock_double_array(struct memblock_type *type,
* needn't do it
*/
if (!use_slab)
- BUG_ON(memblock_reserve(addr, new_alloc_size));
+ BUG_ON(memblock_reserve_kern(addr, new_alloc_size));

/* Update slab flag */
*in_slab = use_slab;
@@ -642,7 +642,7 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
#ifdef CONFIG_NUMA
WARN_ON(nid != memblock_get_region_node(rgn));
#endif
- WARN_ON(flags != rgn->flags);
+ WARN_ON(flags != MEMBLOCK_NONE && flags != rgn->flags);
nr_new++;
if (insert) {
if (start_rgn == -1)
@@ -902,14 +902,15 @@ int __init_memblock memblock_phys_free(phys_addr_t base, phys_addr_t size)
return memblock_remove_range(&memblock.reserved, base, size);
}

-int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
+int __init_memblock __memblock_reserve(phys_addr_t base, phys_addr_t size,
+ int nid, enum memblock_flags flags)
{
phys_addr_t end = base + size - 1;

- memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
- &base, &end, (void *)_RET_IP_);
+ memblock_dbg("%s: [%pa-%pa] nid=%d flags=%x %pS\n", __func__,
+ &base, &end, nid, flags, (void *)_RET_IP_);

- return memblock_add_range(&memblock.reserved, base, size, MAX_NUMNODES, 0);
+ return memblock_add_range(&memblock.reserved, base, size, nid, flags);
}

#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
@@ -1460,14 +1461,14 @@ phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
again:
found = memblock_find_in_range_node(size, align, start, end, nid,
flags);
- if (found && !memblock_reserve(found, size))
+ if (found && !__memblock_reserve(found, size, nid, MEMBLOCK_RSRV_KERN))
goto done;

if (numa_valid_node(nid) && !exact_nid) {
found = memblock_find_in_range_node(size, align, start,
end, NUMA_NO_NODE,
flags);
- if (found && !memblock_reserve(found, size))
+ if (found && !memblock_reserve_kern(found, size))
goto done;
}

@@ -1752,6 +1753,28 @@ phys_addr_t __init_memblock memblock_reserved_size(void)
return memblock.reserved.total_size;
}

+phys_addr_t __init_memblock memblock_reserved_kern_size(phys_addr_t limit, int nid)
+{
+ struct memblock_region *r;
+ phys_addr_t total = 0;
+
+ for_each_reserved_mem_region(r) {
+ phys_addr_t size = r->size;
+
+ if (r->base > limit)
+ break;
+
+ if (r->base + r->size > limit)
+ size = limit - r->base;
+
+ if (nid == memblock_get_region_node(r) || !numa_valid_node(nid))
+ if (r->flags & MEMBLOCK_RSRV_KERN)
+ total += size;
+ }
+
+ return total;
+}
+
/**
* memblock_estimated_nr_free_pages - return estimated number of free pages
* from memblock point of view
@@ -2441,6 +2464,7 @@ static const char * const flagname[] = {
[ilog2(MEMBLOCK_NOMAP)] = "NOMAP",
[ilog2(MEMBLOCK_DRIVER_MANAGED)] = "DRV_MNG",
[ilog2(MEMBLOCK_RSRV_NOINIT)] = "RSV_NIT",
+ [ilog2(MEMBLOCK_RSRV_KERN)] = "RSV_KERN",
};

static int memblock_debug_show(struct seq_file *m, void *private)
diff --git a/tools/testing/memblock/tests/alloc_api.c b/tools/testing/memblock/tests/alloc_api.c
index 68f1a75cd72c4..c55f67dd367d0 100644
--- a/tools/testing/memblock/tests/alloc_api.c
+++ b/tools/testing/memblock/tests/alloc_api.c
@@ -134,7 +134,7 @@ static int alloc_top_down_before_check(void)
PREFIX_PUSH();
setup_memblock();

- memblock_reserve(memblock_end_of_DRAM() - total_size, r1_size);
+ memblock_reserve_kern(memblock_end_of_DRAM() - total_size, r1_size);

allocated_ptr = run_memblock_alloc(r2_size, SMP_CACHE_BYTES);

@@ -182,7 +182,7 @@ static int alloc_top_down_after_check(void)

total_size = r1.size + r2_size;

- memblock_reserve(r1.base, r1.size);
+ memblock_reserve_kern(r1.base, r1.size);

allocated_ptr = run_memblock_alloc(r2_size, SMP_CACHE_BYTES);

@@ -231,8 +231,8 @@ static int alloc_top_down_second_fit_check(void)

total_size = r1.size + r2.size + r3_size;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc(r3_size, SMP_CACHE_BYTES);

@@ -285,8 +285,8 @@ static int alloc_in_between_generic_check(void)

total_size = r1.size + r2.size + r3_size;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc(r3_size, SMP_CACHE_BYTES);

@@ -422,7 +422,7 @@ static int alloc_limited_space_generic_check(void)
setup_memblock();

/* Simulate almost-full memory */
- memblock_reserve(memblock_start_of_DRAM(), reserved_size);
+ memblock_reserve_kern(memblock_start_of_DRAM(), reserved_size);

allocated_ptr = run_memblock_alloc(available_size, SMP_CACHE_BYTES);

@@ -608,7 +608,7 @@ static int alloc_bottom_up_before_check(void)
PREFIX_PUSH();
setup_memblock();

- memblock_reserve(memblock_start_of_DRAM() + r1_size, r2_size);
+ memblock_reserve_kern(memblock_start_of_DRAM() + r1_size, r2_size);

allocated_ptr = run_memblock_alloc(r1_size, SMP_CACHE_BYTES);

@@ -655,7 +655,7 @@ static int alloc_bottom_up_after_check(void)

total_size = r1.size + r2_size;

- memblock_reserve(r1.base, r1.size);
+ memblock_reserve_kern(r1.base, r1.size);

allocated_ptr = run_memblock_alloc(r2_size, SMP_CACHE_BYTES);

@@ -705,8 +705,8 @@ static int alloc_bottom_up_second_fit_check(void)

total_size = r1.size + r2.size + r3_size;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc(r3_size, SMP_CACHE_BYTES);

diff --git a/tools/testing/memblock/tests/alloc_helpers_api.c b/tools/testing/memblock/tests/alloc_helpers_api.c
index 3ef9486da8a09..e5362cfd2ff30 100644
--- a/tools/testing/memblock/tests/alloc_helpers_api.c
+++ b/tools/testing/memblock/tests/alloc_helpers_api.c
@@ -163,7 +163,7 @@ static int alloc_from_top_down_no_space_above_check(void)
min_addr = memblock_end_of_DRAM() - SMP_CACHE_BYTES * 2;

/* No space above this address */
- memblock_reserve(min_addr, r2_size);
+ memblock_reserve_kern(min_addr, r2_size);

allocated_ptr = memblock_alloc_from(r1_size, SMP_CACHE_BYTES, min_addr);

@@ -199,7 +199,7 @@ static int alloc_from_top_down_min_addr_cap_check(void)
start_addr = (phys_addr_t)memblock_start_of_DRAM();
min_addr = start_addr - SMP_CACHE_BYTES * 3;

- memblock_reserve(start_addr + r1_size, MEM_SIZE - r1_size);
+ memblock_reserve_kern(start_addr + r1_size, MEM_SIZE - r1_size);

allocated_ptr = memblock_alloc_from(r1_size, SMP_CACHE_BYTES, min_addr);

diff --git a/tools/testing/memblock/tests/alloc_nid_api.c b/tools/testing/memblock/tests/alloc_nid_api.c
index 49bb416d34ffc..562e4701b0e02 100644
--- a/tools/testing/memblock/tests/alloc_nid_api.c
+++ b/tools/testing/memblock/tests/alloc_nid_api.c
@@ -324,7 +324,7 @@ static int alloc_nid_min_reserved_generic_check(void)
min_addr = max_addr - r2_size;
reserved_base = min_addr - r1_size;

- memblock_reserve(reserved_base, r1_size);
+ memblock_reserve_kern(reserved_base, r1_size);

allocated_ptr = run_memblock_alloc_nid(r2_size, SMP_CACHE_BYTES,
min_addr, max_addr,
@@ -374,7 +374,7 @@ static int alloc_nid_max_reserved_generic_check(void)
max_addr = memblock_end_of_DRAM() - r1_size;
min_addr = max_addr - r2_size;

- memblock_reserve(max_addr, r1_size);
+ memblock_reserve_kern(max_addr, r1_size);

allocated_ptr = run_memblock_alloc_nid(r2_size, SMP_CACHE_BYTES,
min_addr, max_addr,
@@ -436,8 +436,8 @@ static int alloc_nid_top_down_reserved_with_space_check(void)
min_addr = r2.base + r2.size;
max_addr = r1.base;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc_nid(r3_size, SMP_CACHE_BYTES,
min_addr, max_addr,
@@ -499,8 +499,8 @@ static int alloc_nid_reserved_full_merge_generic_check(void)
min_addr = r2.base + r2.size;
max_addr = r1.base;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc_nid(r3_size, SMP_CACHE_BYTES,
min_addr, max_addr,
@@ -563,8 +563,8 @@ static int alloc_nid_top_down_reserved_no_space_check(void)
min_addr = r2.base + r2.size;
max_addr = r1.base;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc_nid(r3_size, SMP_CACHE_BYTES,
min_addr, max_addr,
@@ -909,8 +909,8 @@ static int alloc_nid_bottom_up_reserved_with_space_check(void)
min_addr = r2.base + r2.size;
max_addr = r1.base;

- memblock_reserve(r1.base, r1.size);
- memblock_reserve(r2.base, r2.size);
+ memblock_reserve_kern(r1.base, r1.size);
+ memblock_reserve_kern(r2.base, r2.size);

allocated_ptr = run_memblock_alloc_nid(r3_size, SMP_CACHE_BYTES,
min_addr, max_addr,
--
2.49.0.906.g1f30a19c02-goog