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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 1/3] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
Date: Tue, 18 May 2021 12:06:11 +0300	[thread overview]
Message-ID: <20210518090613.21519-2-rppt@kernel.org> (raw)
In-Reply-To: <20210518090613.21519-1-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


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WARNING: multiple messages have this Message-ID (diff)
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 1/3] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
Date: Tue, 18 May 2021 12:06:11 +0300	[thread overview]
Message-ID: <20210518090613.21519-2-rppt@kernel.org> (raw)
In-Reply-To: <20210518090613.21519-1-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:[~2021-05-18  9:08 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-18  9:06 [PATCH 0/3] memblock, arm: fixes for freeing of the memory map Mike Rapoport
2021-05-18  9:06 ` Mike Rapoport
2021-05-18  9:06 ` Mike Rapoport [this message]
2021-05-18  9:06   ` [PATCH 1/3] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER Mike Rapoport
2021-05-18  9:06 ` [PATCH 2/3] memblock: align freed memory map on pageblock boundaries with SPARSEMEM Mike Rapoport
2021-05-18  9:06   ` Mike Rapoport
2021-05-18  9:06 ` [PATCH 3/3] arm: extend pfn_valid to take into accound freed memory map alignment Mike Rapoport
2021-05-18  9:06   ` Mike Rapoport
2021-05-18  9:44   ` Russell King (Oracle)
2021-05-18  9:44     ` Russell King (Oracle)
2021-05-18 10:53     ` Mike Rapoport
2021-05-18 10:53       ` Mike Rapoport
2021-05-18 12:49   ` Kefeng Wang
2021-05-18 12:49     ` Kefeng Wang
2021-05-18 15:52     ` Mike Rapoport
2021-05-18 15:52       ` Mike Rapoport
2021-05-19  1:50       ` Kefeng Wang
2021-05-19  1:50         ` Kefeng Wang
2021-05-19 13:25         ` Mike Rapoport
2021-05-19 13:25           ` Mike Rapoport

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