Patch "arm: extend pfn_valid to take into account freed memory map alignment" 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

    arm: extend pfn_valid to take into account freed memory map alignment

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:
     arm-extend-pfn_valid-to-take-into-account-freed-memory-map-alignment.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 16:57:09 +0800
Subject: arm: extend pfn_valid to take into account freed memory map alignment
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: <20211213085710.28962-5-mark-pk.tsai at mediatek.com>

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

commit a4d5613c4dc6d413e0733e37db9d116a2a36b9f3 upstream.

When unused memory map is freed the preserved part of the memory map is
extended to match pageblock boundaries because lots of core mm
functionality relies on homogeneity of the memory map within pageblock
boundaries.

Since pfn_valid() is used to check whether there is a valid memory map
entry for a PFN, make it return true also for PFNs that have memory map
entries even if there is no actual memory populated there.

Signed-off-by: Mike Rapoport <rppt at linux.ibm.com>
Tested-by: Kefeng Wang <wangkefeng.wang at huawei.com>
Tested-by: Tony Lindgren <tony at atomide.com>
Link: https://lore.kernel.org/lkml/20210630071211.21011-1-rppt@kernel.org/
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 |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -176,11 +176,22 @@ static void __init zone_sizes_init(unsig
 int pfn_valid(unsigned long pfn)
 {
 	phys_addr_t addr = __pfn_to_phys(pfn);
+	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
 
 	if (__phys_to_pfn(addr) != pfn)
 		return 0;
 
-	return memblock_is_map_memory(__pfn_to_phys(pfn));
+	/*
+	 * If address less than pageblock_size bytes away from a present
+	 * memory chunk there still will be a memory map entry for it
+	 * because we round freed memory map to the pageblock boundaries.
+	 */
+	if (memblock_overlaps_region(&memblock.memory,
+				     ALIGN_DOWN(addr, pageblock_size),
+				     pageblock_size))
+		return 1;
+
+	return 0;
 }
 EXPORT_SYMBOL(pfn_valid);
 #endif


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