[PATCH 5.10 1/5] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
Mark-PK Tsai
mark-pk.tsai at mediatek.com
Mon Dec 13 01:41:31 PST 2021
From: Mike Rapoport <rppt at linux.ibm.com>
[ Upstream commit e2a86800d58639b3acde7eaeb9eb393dca066e08 ]
The code that frees unused memory map uses rounds start and end of the
holes that are freed to MAX_ORDER_NR_PAGES to preserve continuity of the
memory map for MAX_ORDER regions.
Lots of core memory management functionality relies on homogeneity of the
memory map within each pageblock which size may differ from MAX_ORDER in
certain configurations.
Although currently, for the architectures that use free_unused_memmap(),
pageblock_order and MAX_ORDER are equivalent, it is cleaner to have common
notation thought mm code.
Replace MAX_ORDER_NR_PAGES with pageblock_nr_pages and update the comments
to make it more clear why the alignment to pageblock boundaries is
required.
Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>
Tested-by: Tony Lindgren <tony at atomide.com>
Link: https://lore.kernel.org/lkml/20210630071211.21011-1-rppt@kernel.org/
[backport upstream modification in mm/memblock.c to arch/arm/mm/init.c]
Signed-off-by: Mark-PK Tsai <mark-pk.tsai at mediatek.com>
---
arch/arm/mm/init.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 75f3ab531bdf..8440b6027598 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -315,11 +315,11 @@ static void __init free_unused_memmap(void)
ALIGN(prev_end, PAGES_PER_SECTION));
#else
/*
- * Align down here since the VM subsystem insists that the
- * memmap entries are valid from the bank start aligned to
- * MAX_ORDER_NR_PAGES.
+ * Align down here since many operations in VM subsystem
+ * presume that there are no holes in the memory map inside
+ * a pageblock
*/
- start = round_down(start, MAX_ORDER_NR_PAGES);
+ start = round_down(start, pageblock_nr_pages);
#endif
/*
* If we had a previous bank, and there is a space
@@ -329,11 +329,11 @@ static void __init free_unused_memmap(void)
free_memmap(prev_end, start);
/*
- * Align up here since the VM subsystem insists that the
- * memmap entries are valid from the bank end aligned to
- * MAX_ORDER_NR_PAGES.
+ * Align up here since many operations in VM subsystem
+ * presume that there are no holes in the memory map inside
+ * a pageblock
*/
- prev_end = ALIGN(end, MAX_ORDER_NR_PAGES);
+ prev_end = ALIGN(end, pageblock_nr_pages);
}
#ifdef CONFIG_SPARSEMEM
--
2.18.0
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