+ mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch added to mm-hotfixes-unstable branch

+ mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/memory_hotplug: fix memory block reference leak on remove
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm/memory_hotplug: fix memory block reference leak on remove
Date: Sun, 26 Apr 2026 22:44:46 +0800

remove_memory_blocks_and_altmaps() looks up each memory block with
find_memory_block(), which acquires a reference to the memory block
device.

That reference is never dropped on this path, resulting in a leaked device
reference when removing memory blocks and their altmaps.  Drop the
reference after retrieving mem->altmap and clearing mem->altmap, before
removing the memory block device.

Link: https://lore.kernel.org/20260426144447.817722-1-songmuchun@bytedance.com
Fixes: 6b8f0798b85a ("mm/memory_hotplug: split memmap_on_memory requests across memblocks")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Huang, Ying" <huang.ying.caritas@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory_hotplug.c |    1 +
 1 file changed, 1 insertion(+)

--- a/mm/memory_hotplug.c~mm-memory_hotplug-fix-memory-block-reference-leak-on-remove
+++ a/mm/memory_hotplug.c
@@ -1422,6 +1422,7 @@ static void remove_memory_blocks_and_alt
 
 		altmap = mem->altmap;
 		mem->altmap = NULL;
+		put_device(&mem->dev);
 
 		remove_memory_block_devices(cur_start, memblock_size);
 
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch
drivers-base-memory-fix-memory-block-reference-leak-in-poison-accounting.patch
mm-sparse-remove-sparse-buffer-pre-allocation-mechanism.patch