From 11684134140bb708b6e6de969a060535630b1b53 Mon Sep 17 00:00:00 2001
From: Sumanth Korikkar <sumanthk@linux.ibm.com>
Date: Wed, 10 Jan 2024 15:01:27 +0100
Subject: [PATCH] mm/memory_hotplug: fix memmap_on_memory sysfs value retrieval
set_memmap_mode() stores the kernel parameter memmap mode as an integer.
However, the get_memmap_mode() function utilizes param_get_bool() to fetch
the value as a boolean, leading to potential endianness issue. On
Big-endian architectures, the memmap_on_memory is consistently displayed
as 'N' regardless of its actual status.
To address this endianness problem, the solution involves obtaining the
mode as an integer. This adjustment ensures the proper display of the
memmap_on_memory parameter, presenting it as one of the following options:
Force, Y, or N.
Link: https://lkml.kernel.org/r/20240110140127.241451-1-sumanthk@linux.ibm.com
Fixes: 2d1f649c7c08 ("mm/memory_hotplug: support memmap_on_memory when memmap is not aligned to pageblocks")
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Suggested-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: <stable@vger.kernel.org> [6.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/memory_hotplug.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b3c0ff52bb72e..21890994c1d3c 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -101,9 +101,11 @@ static int set_memmap_mode(const char *val, const struct kernel_param *kp)
static int get_memmap_mode(char *buffer, const struct kernel_param *kp)
{
- if (*((int *)kp->arg) == MEMMAP_ON_MEMORY_FORCE)
- return sprintf(buffer, "force\n");
- return param_get_bool(buffer, kp);
+ int mode = *((int *)kp->arg);
+
+ if (mode == MEMMAP_ON_MEMORY_FORCE)
+ return sprintf(buffer, "force\n");
+ return sprintf(buffer, "%c\n", mode ? 'Y' : 'N');
}
static const struct kernel_param_ops memmap_mode_ops = {