[PATCH v4 1/3] mm: memblock enhence the memblock debugfs output

[PATCH v4 1/3] mm: memblock enhence the memblock debugfs output

[Dennis Chen]

Current memblock debugfs output doesn't make the debug convenient
enough, for example, lack of the 'flag' of the corresponding memblock
region result in it's difficult to known whether the region has been
mapped to the kernel linear map zone or not. This patch is trying to
ease the dubug effort by adding 'size' and 'flag' output.

The '/sys/kernel/debug/memblock/memory' output looks like before:
   0: 0x0000008000000000..0x0000008001e7ffff
   1: 0x0000008001e80000..0x00000083ff184fff
   2: 0x00000083ff185000..0x00000083ff1c2fff
   3: 0x00000083ff1c3000..0x00000083ff222fff
   4: 0x00000083ff223000..0x00000083ffe42fff
   5: 0x00000083ffe43000..0x00000083ffffffff

After applied:
   0: 0x0000008000000000..0x0000008001e7ffff  0x0000000001e80000  0x4
   1: 0x0000008001e80000..0x00000083ff184fff  0x00000003fd305000  0x0
   2: 0x00000083ff185000..0x00000083ff1c2fff  0x000000000003e000  0x4
   3: 0x00000083ff1c3000..0x00000083ff222fff  0x0000000000060000  0x0
   4: 0x00000083ff223000..0x00000083ffe42fff  0x0000000000c20000  0x4
   5: 0x00000083ffe43000..0x00000083ffffffff  0x00000000001bd000  0x0

Signed-off-by: Dennis Chen <dennis.chen@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: linux-mm@kvack.org
Cc: linux-acpi@vger.kernel.org
Cc: linux-efi@vger.kernel.org
---
Change history:
v3->v4: 
According to suggestion from Mark Rutland, make the memblock debugfs
part as an individual patch since logically it's independent from others

 mm/memblock.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index ca09915..0fc0fa1 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1677,13 +1677,15 @@ static int memblock_debug_show(struct seq_file *m, void *private)
 		reg = &type->regions[i];
 		seq_printf(m, "%4d: ", i);
 		if (sizeof(phys_addr_t) == 4)
-			seq_printf(m, "0x%08lx..0x%08lx\n",
+			seq_printf(m, "0x%08lx..0x%08lx  0x%08lx  0x%lx\n",
 				   (unsigned long)reg->base,
-				   (unsigned long)(reg->base + reg->size - 1));
+				   (unsigned long)(reg->base + reg->size - 1),
+				   (unsigned long)reg->size, reg->flags);
 		else
-			seq_printf(m, "0x%016llx..0x%016llx\n",
+			seq_printf(m, "0x%016llx..0x%016llx  0x%016llx  0x%lx\n",
 				   (unsigned long long)reg->base,
-				   (unsigned long long)(reg->base + reg->size - 1));
+				   (unsigned long long)(reg->base + reg->size - 1),
+				   (unsigned long long)reg->size, reg->flags);
 
 	}
 	return 0;
-- 
2.7.4

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[PATCH v4 2/3] mm: memblock Add some new functions to address the mem limit issue

[Dennis Chen]

In some cases, memblock is queried to determine whether a physical
address corresponds to memory present in a system even if unused by
the OS for the linear mapping, highmem, etc. For example, the ACPI
core needs this information to determine which attributes to use when
mapping ACPI regions. Use of incorrect memory types can result in
faults, data corruption, or other issues.

Removing memory with memblock_enforce_memory_limit throws away this
information, and so a kernel booted with 'mem=' may suffers from the
issues described above. To avoid this, we need to kept those nomap
regions instead of removing all above limit, which preserves the
information we need while preventing other use of the regions.

This patch adds new insfrastructure to kept all nomap memblock regions
while removing others, to cater for this.

Signed-off-by: Dennis Chen <dennis.chen@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: linux-mm@kvack.org
Cc: linux-acpi@vger.kernel.org
Cc: linux-efi@vger.kernel.org
---
Change history
v1->v2: Mark all regions above the limit as NOMAP per Mark's suggestion
v2->v3: Only keep the NOMAP regions above limit while removing all
ohters according to the proposal from Ard's
v3->v4: Incorporate some review comments from Mark Rutland.

 include/linux/memblock.h |  1 +
 mm/memblock.c            | 54 +++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 6c14b61..2925da2 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -332,6 +332,7 @@ phys_addr_t memblock_mem_size(unsigned long limit_pfn);
 phys_addr_t memblock_start_of_DRAM(void);
 phys_addr_t memblock_end_of_DRAM(void);
 void memblock_enforce_memory_limit(phys_addr_t memory_limit);
+void memblock_mem_limit_remove_map(phys_addr_t limit);
 bool memblock_is_memory(phys_addr_t addr);
 int memblock_is_map_memory(phys_addr_t addr);
 int memblock_is_region_memory(phys_addr_t base, phys_addr_t size);
diff --git a/mm/memblock.c b/mm/memblock.c
index 0fc0fa1..993f597 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1465,15 +1465,16 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void)
 	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
 }
 
-void __init memblock_enforce_memory_limit(phys_addr_t limit)
+static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
 {
 	phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
 	struct memblock_region *r;
 
-	if (!limit)
-		return;
-
-	/* find out max address */
+	/*
+	 * translate the memory @limit size into the max address within one of
+	 * the memory memblock regions, if the @limit exceeds the total size
+	 * of those regions, max_addr will keep original value ULLONG_MAX
+	 */
 	for_each_memblock(memory, r) {
 		if (limit <= r->size) {
 			max_addr = r->base + limit;
@@ -1482,6 +1483,23 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
 		limit -= r->size;
 	}
 
+	return max_addr;
+}
+
+void __init memblock_enforce_memory_limit(phys_addr_t limit)
+{
+	phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
+	struct memblock_region *r;
+
+	if (!limit)
+		return;
+
+	max_addr = __find_max_addr(limit);
+
+	/* @limit exceeds the total size of the memory, do nothing */
+	if (max_addr == (phys_addr_t)ULLONG_MAX)
+		return;
+
 	/* truncate both memory and reserved regions */
 	memblock_remove_range(&memblock.memory, max_addr,
 			      (phys_addr_t)ULLONG_MAX);
@@ -1489,6 +1507,32 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
 			      (phys_addr_t)ULLONG_MAX);
 }
 
+void __init memblock_mem_limit_remove_map(phys_addr_t limit)
+{
+	struct memblock_type *type = &memblock.memory;
+	phys_addr_t max_addr;
+	int i, ret, start_rgn, end_rgn;
+
+	if (!limit)
+		return;
+
+	max_addr = __find_max_addr(limit);
+
+	/* @limit exceeds the total size of the memory, do nothing */
+	if (max_addr == (phys_addr_t)ULLONG_MAX)
+		return;
+
+	ret = memblock_isolate_range(type, max_addr, (phys_addr_t)ULLONG_MAX,
+				&start_rgn, &end_rgn);
+	if (ret)
+		return;
+
+	for (i = end_rgn - 1; i >= start_rgn; i--) {
+		if (!memblock_is_nomap(&type->regions[i]))
+			memblock_remove_region(type, i);
+	}
+}
+
 static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
 {
 	unsigned int left = 0, right = type->cnt;
-- 
2.7.4

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Re: [PATCH v4 2/3] mm: memblock Add some new functions to address the mem limit issue

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1748 bytes --]

Hi,

[auto build test WARNING on arm64/for-next/core]
[also build test WARNING on v4.7-rc5 next-20160627]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dennis-Chen/mm-memblock-enhence-the-memblock-debugfs-output/20160628-174951
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
config: i386-randconfig-i0-201626 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-1) 6.1.1 20160430
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

   mm/memblock.c: In function 'memblock_enforce_memory_limit':
>> mm/memblock.c:1489:26: warning: unused variable 'r' [-Wunused-variable]
     struct memblock_region *r;
                             ^

vim +/r +1489 mm/memblock.c

  1473		 * of those regions, max_addr will keep original value ULLONG_MAX
  1474		 */
  1475		for_each_memblock(memory, r) {
  1476			if (limit <= r->size) {
  1477				max_addr = r->base + limit;
  1478				break;
  1479			}
  1480			limit -= r->size;
  1481		}
  1482	
  1483		return max_addr;
  1484	}
  1485	
  1486	void __init memblock_enforce_memory_limit(phys_addr_t limit)
  1487	{
  1488		phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
> 1489		struct memblock_region *r;
  1490	
  1491		if (!limit)
  1492			return;
  1493	
  1494		max_addr = __find_max_addr(limit);
  1495	
  1496		/* @limit exceeds the total size of the memory, do nothing */
  1497		if (max_addr == (phys_addr_t)ULLONG_MAX)

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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