[PATCH v6 24/36] powerpc/fadump: make use of memblock's bottom up allocation mode

[Hari Bathini]

Earlier, memblock_find_in_range() was not used to find the memory to
be reserved for FADump as bottom up allocation mode was not supported.
But since commit 79442ed189acb8b ("mm/memblock.c: introduce bottom-up
allocation mode") bottom up allocation mode is supported for memblock.
So, use it to find the memory to be reserved for FADump.

Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
---

Changes in v6:
  * Avoid hacky code and use memblock_find_in_range with bottom up
    allocation mode supported now.


 arch/powerpc/kernel/fadump.c |   26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 852ac47..da75140 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -342,7 +342,8 @@ static void __init fadump_reserve_crash_area(unsigned long 
base,
 
 int __init fadump_reserve_mem(void)
 {
-       u64 base, size, mem_boundary;
+       bool is_memblock_bottom_up = memblock_bottom_up();
+       u64 base, size, mem_boundary, align = PAGE_SIZE;
        int ret = 1;
 
        if (!fw_dump.fadump_enabled)
@@ -362,10 +363,11 @@ int __init fadump_reserve_mem(void)
                fw_dump.boot_memory_size =
                        PAGE_ALIGN(fadump_calculate_reserve_size());
 #ifdef CONFIG_CMA
-               if (!fw_dump.nocma)
+               if (!fw_dump.nocma) {
+                       align = FADUMP_CMA_ALIGNMENT;
                        fw_dump.boot_memory_size =
-                               ALIGN(fw_dump.boot_memory_size,
-                                                       FADUMP_CMA_ALIGNMENT);
+                               ALIGN(fw_dump.boot_memory_size, align);
+               }
 #endif
        }
 
@@ -419,19 +421,15 @@ int __init fadump_reserve_mem(void)
        } else {
                /*
                 * Reserve memory at an offset closer to bottom of the RAM to
-                * minimize the impact of memory hot-remove operation. We can't
-                * use memblock_find_in_range() here since it doesn't allocate
-                * from bottom to top.
+                * minimize the impact of memory hot-remove operation.
                 */
-               while (base <= (mem_boundary - size)) {
-                       if (memblock_is_region_memory(base, size) &&
-                           !memblock_is_region_reserved(base, size))
-                               break;
+               memblock_set_bottom_up(true);
+               base = memblock_find_in_range(base, mem_boundary, size, align);
 
-                       base += size;
-               }
+               /* Restore the previous allocation mode */
+               memblock_set_bottom_up(is_memblock_bottom_up);
 
-               if (base > (mem_boundary - size)) {
+               if (!base) {
                        pr_err("Failed to find memory chunk for 
reservation!\n");
                        goto error_out;
                }