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From: Mike Rapoport <rppt@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Mike Rapoport <rppt@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH v2 1/3] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
Date: Wed, 19 May 2021 17:14:34 +0300	[thread overview]
Message-ID: <20210519141436.11961-2-rppt@kernel.org> (raw)
In-Reply-To: <20210519141436.11961-1-rppt@kernel.org>

From: Mike Rapoport <rppt@linux.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@linux.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


  reply	other threads:[~2021-05-19 14:16 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 14:14 [PATCH v2 0/3] memblock, arm: fixes for freeing of the memory map Mike Rapoport
2021-05-19 14:14 ` Mike Rapoport [this message]
2021-05-19 14:14 ` [PATCH v2 2/3] memblock: align freed memory map on pageblock boundaries with SPARSEMEM Mike Rapoport
2021-05-19 14:14 ` [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment Mike Rapoport
2021-06-28 10:20   ` Tony Lindgren
2021-06-28 13:16     ` Mike Rapoport
2021-06-28 15:26       ` Tony Lindgren
2021-06-29  5:33         ` Mike Rapoport
2021-06-29  8:54           ` Tony Lindgren
2021-06-29 10:50             ` Mike Rapoport
2021-06-29 11:52               ` Tony Lindgren
2021-06-29 12:50                 ` Mike Rapoport
2021-06-29 12:53                   ` Tony Lindgren
2021-06-30  7:20                   ` Mike Rapoport
2021-05-20  6:21 ` [PATCH v2 0/3] memblock, arm: fixes for freeing of the memory map Kefeng Wang

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