From: Muchun Song Date: Tue, 28 Apr 2026 08:52:17 +0000 (+0800) Subject: mm/memory_hotplug: fix memory block reference leak on remove X-Git-Tag: v7.1-rc5~52^2~3 X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=93866f55f7e292fe3d47d36c9efe5ee10213a06b;p=thirdparty%2Fkernel%2Flinux.git mm/memory_hotplug: fix memory block reference leak on remove Patch series "mm: Fix memory block leaks and locking", v2. This series fixes two memory block device reference leaks and one locking issue around the per-memory_block hwpoison counter. This patch (of 2): 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/20260428085219.1316047-1-songmuchun@bytedance.com Link: https://lore.kernel.org/20260428085219.1316047-2-songmuchun@bytedance.com Fixes: 6b8f0798b85a ("mm/memory_hotplug: split memmap_on_memory requests across memblocks") Signed-off-by: Muchun Song Acked-by: Oscar Salvador Acked-by: David Hildenbrand (Arm) Cc: Danilo Krummrich Cc: Greg Kroah-Hartman Cc: "Huang, Ying" Cc: Miaohe Lin Cc: Naoya Horiguchi Cc: "Rafael J. Wysocki" Cc: Vishal Verma Cc: Signed-off-by: Andrew Morton --- diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 2a943ec57c85b..40c7915dabe05 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1422,6 +1422,8 @@ static void remove_memory_blocks_and_altmaps(u64 start, u64 size) altmap = mem->altmap; mem->altmap = NULL; + /* drop the ref. we got via find_memory_block() */ + put_device(&mem->dev); remove_memory_block_devices(cur_start, memblock_size);