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Message-Id: <20210630071211.21011-2-rppt@kernel.org>
Date: Wed, 30 Jun 2021 10:12:08 +0300
From: Mike Rapoport <rppt@...nel.org>
To: linux-arm-kernel@...ts.infradead.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Mike Rapoport <rppt@...nel.org>,
Russell King <linux@...linux.org.uk>,
Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: [PATCH v3 1/4] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
From: Mike Rapoport <rppt@...ux.ibm.com>
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@...ux.ibm.com>
---
mm/memblock.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/mm/memblock.c b/mm/memblock.c
index afaefa8fc6ab..97fa87541b5f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1943,11 +1943,11 @@ static void __init free_unused_memmap(void)
start = min(start, 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
/*
@@ -1958,11 +1958,11 @@ 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
--
2.28.0
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