linux-kernel - [RESEND PATCH 04/10] memblock: take a region intersecting an unknown region

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Message-Id: <20240521023957.2587005-5-jaewon31.kim@samsung.com>
Date: Tue, 21 May 2024 11:39:51 +0900
From: Jaewon Kim <jaewon31.kim@...sung.com>
To: rppt@...nel.org, vbabka@...e.cz, akpm@...ux-foundation.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	jaewon31.kim@...il.com, Jaewon Kim <jaewon31.kim@...sung.com>
Subject: [RESEND PATCH 04/10] 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.

Signed-off-by: Jaewon Kim <jaewon31.kim@...sung.com>
---
 mm/memblock.c | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index 4a0506e14025..9b68ddc4af5e 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -2081,20 +2081,54 @@ 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;
-- 
2.25.1