From f3f83a6edfc535e18f3de9ab8aa56fb7b4edb3f6 Mon Sep 17 00:00:00 2001
From: Jaewon Kim <jaewon31.kim@samsung.com>
Date: Thu, 20 Apr 2023 12:17:49 +0900
Subject: [PATCH] ANDROID: memblock: take a region intersecting an unknown
 region

There is case where reserved regions overlapped with already checked as
unknown regions. To get more information of the name, size, so far we
allowed only regions which are exactly matching with or located within
the unknown region.

For a region intersecting an unknown region, we did not take and just
showed that duplicated information. So total size was not perfect. To
fix this, let's allow to take even the intersecting region.

Bug: 340432773
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Link: https://lore.kernel.org/linux-mm/20240521023957.2587005-5-jaewon31.kim@samsung.com/
Change-Id: I3ab0bdcea5e9122f59b87e13afafc2c9b9606295
---
 mm/memblock.c | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index 04925e35eedd..28686dcb8b61 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -2090,20 +2090,54 @@ static bool __init_memblock memsize_update_nomap_region(const char *name, phys_a
 	for (i = 0; i < memsize_rgn_count; i++)	{
 		rmem_rgn = &memsize_rgn[i];
 
+		/* skip either !nomap, !unknown, !overlap */
 		if (!rmem_rgn->nomap)
 			continue;
 		if (strcmp(rmem_rgn->name, "unknown"))
 			continue;
-		if (base < rmem_rgn->base)
+		if (base + size <= rmem_rgn->base)
 			continue;
-		if (base + size > rmem_rgn->base + rmem_rgn->size)
+		if (base >= rmem_rgn->base + rmem_rgn->size)
 			continue;
 
+		/* exactly same */
 		if (base == rmem_rgn->base && size == rmem_rgn->size) {
 			memsize_get_valid_name(rmem_rgn->name, name);
 			return true;
 		}
 
+		/* bigger */
+		if (base <= rmem_rgn->base &&
+				base + size >= rmem_rgn->base + rmem_rgn->size) {
+			memsize_get_valid_name(rmem_rgn->name, name);
+			rmem_rgn->base = base;
+			rmem_rgn->size = size;
+			return true;
+		}
+
+		/* intersect */
+		if (base < rmem_rgn->base ||
+				base + size > rmem_rgn->base + rmem_rgn->size) {
+			new_rgn = memsize_get_new_rgn();
+			if (!new_rgn)
+				return true;
+			new_rgn->base = base;
+			new_rgn->size = size;
+			new_rgn->nomap = nomap;
+			new_rgn->reusable = false;
+			memsize_get_valid_name(new_rgn->name, name);
+
+			if (base < rmem_rgn->base) {
+				rmem_rgn->size -= base + size - rmem_rgn->base;
+				rmem_rgn->base = base + size;
+			} else {
+				rmem_rgn->size -= rmem_rgn->base
+							+ rmem_rgn->size - base;
+			}
+			return true;
+		}
+
+		/* smaller */
 		new_rgn = memsize_get_new_rgn();
 		if (!new_rgn)
 			return true;