From: =?UTF-8?q?Jan=20H=2E=20Sch=C3=B6nherr?= <jschoenh@amazon.de>
Date: Fri, 19 Jan 2018 16:27:54 -0800
Subject: mm: Fix memory size alignment in devm_memremap_pages_release()
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Git-commit: 10a0cd6e4932b5078215b1ec2c896597eec0eff9
Patch-mainline: v4.16-rc1
References: VM Functionality, bsc#1097439

The functions devm_memremap_pages() and devm_memremap_pages_release() use
different ways to calculate the section-aligned amount of memory. The
latter function may use an incorrect size if the memory region is small
but straddles a section border.

Use the same code for both.

Cc: <stable@vger.kernel.org>
Fixes: 5f29a77cd957 ("mm: fix mixed zone detection in devm_memremap_pages")
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 kernel/memremap.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -292,7 +292,8 @@ static void devm_memremap_pages_release(
 
 	/* pages are dead and unused, undo the arch mapping */
 	align_start = res->start & ~(SECTION_SIZE - 1);
-	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+	align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
+		- align_start;
 
 	mem_hotplug_begin();
 	arch_remove_memory(align_start, align_size, pgmap->altmap_valid ?