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Subject[PATCH 02/24] mm/memblock: debug: don't free reserved array if !ARCH_DISCARD_MEMBLOCK
Date
From: Grygorii Strashko <grygorii.strashko@ti.com>

Now the Nobootmem allocator will always try to free memory allocated for
reserved memory regions (free_low_memory_core_early()) without taking
into to account current memblock debugging configuration
(CONFIG_ARCH_DISCARD_MEMBLOCK and CONFIG_DEBUG_FS state).
As result if:
- CONFIG_DEBUG_FS defined
- CONFIG_ARCH_DISCARD_MEMBLOCK not defined;
- reserved memory regions array have been resized during boot

then:
- memory allocated for reserved memory regions array will be freed to
buddy allocator;
- debug_fs entry "sys/kernel/debug/memblock/reserved" will show garbage
instead of state of memory reservations. like:
0: 0x98393bc0..0x9a393bbf
1: 0xff120000..0xff11ffff
2: 0x00000000..0xffffffff

Hence, do not free memory allocated for reserved memory regions if
defined(CONFIG_DEBUG_FS) && !defined(CONFIG_ARCH_DISCARD_MEMBLOCK).

Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
---
mm/memblock.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/mm/memblock.c b/mm/memblock.c
index e03918e..88a6a0e 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -167,6 +167,19 @@ phys_addr_t __init_memblock get_allocated_memblock_reserved_regions_info(
if (memblock.reserved.regions == memblock_reserved_init_regions)
return 0;

+ /*
+ * Don't allow Nobootmem allocator to free reserved memory regions
+ * array if
+ * - CONFIG_DEBUG_FS is enabled;
+ * - CONFIG_ARCH_DISCARD_MEMBLOCK is not enabled;
+ * - reserved memory regions array have been resized during boot.
+ * Otherwise debug_fs entry "sys/kernel/debug/memblock/reserved"
+ * will show garbage instead of state of memory reservations.
+ */
+ if (IS_ENABLED(CONFIG_DEBUG_FS) &&
+ !IS_ENABLED(CONFIG_ARCH_DISCARD_MEMBLOCK))
+ return 0;
+
*addr = __pa(memblock.reserved.regions);

return PAGE_ALIGN(sizeof(struct memblock_region) *
--
1.7.9.5


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