Patch "memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER" has been added to the 5.4-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     memblock-free_unused_memmap-use-pageblock-units-instead-of-max_order.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Wed Dec 15 03:02:39 PM CET 2021
From: Mark-PK Tsai <mark-pk.tsai at mediatek.com>
Date: Mon, 13 Dec 2021 16:57:06 +0800
Subject: memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER
To: <stable at vger.kernel.org>
Cc: <rppt at kernel.org>, <akpm at linux-foundation.org>, <linux-arm-kernel at lists.infradead.org>, <linux-kernel at vger.kernel.org>, <linux-mm at kvack.org>, <linux at armlinux.org.uk>, <rppt at linux.ibm.com>, <tony at atomide.com>, <wangkefeng.wang at huawei.com>, <mark-pk.tsai at mediatek.com>, <yj.chiang at mediatek.com>
Message-ID: <20211213085710.28962-2-mark-pk.tsai at mediatek.com>

From: Mike Rapoport <rppt at linux.ibm.com>

commit e2a86800d58639b3acde7eaeb9eb393dca066e08 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 arch/arm/mm/init.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -373,11 +373,11 @@ static void __init free_unused_memmap(vo
 				 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
@@ -387,12 +387,12 @@ static void __init free_unused_memmap(vo
 			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(memblock_region_memory_end_pfn(reg),
-				 MAX_ORDER_NR_PAGES);
+				 pageblock_nr_pages);
 	}
 
 #ifdef CONFIG_SPARSEMEM


Patches currently in stable-queue which might be from mark-pk.tsai at mediatek.com are

queue-5.4/arm-extend-pfn_valid-to-take-into-account-freed-memory-map-alignment.patch
queue-5.4/arm-ioremap-don-t-abuse-pfn_valid-to-check-if-pfn-is-in-ram.patch
queue-5.4/memblock-free_unused_memmap-use-pageblock-units-instead-of-max_order.patch
queue-5.4/memblock-align-freed-memory-map-on-pageblock-boundaries-with-sparsemem.patch
queue-5.4/memblock-ensure-there-is-no-overflow-in-memblock_overlaps_region.patch