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From:   Wupeng Ma <mawupeng1@huawei.com>
To:     <akpm@linux-foundation.org>, <david@redhat.com>
CC:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <mawupeng1@huawei.com>, <stable@vger.kernel.org>
Subject: [PATCH stable 5.10 0/1] Fix memleak during hotremove memory
Date:   Wed, 14 Jun 2023 14:18:59 +0800
Message-ID: <20230614061900.3296725-1-mawupeng1@huawei.com>
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From: Ma Wupeng <mawupeng1@huawei.com>

Hi maintainers:

Our test find a memleak in init_memory_block, it is clear that mem is never
been released due to wrong refcount. Commit 08b3acd7a68f ("mm/memory_hotplug:
Introduce offline_and_remove_memory()") failed to dec refcount after
find_memory_block which fail to dec refcount to zero in remove memory
causing the leak.

Commit 8dc4bb58a146 ("mm/memory_hotplug: extend offline_and_remove_memory()
to handle more than one memory block") introduce walk_memory_blocks to
replace find_memory_block which dec refcount by calling put_device after
find_memory_block_by_id. In the way, the memleak is fixed.

Here is the simplified calltrace:

  kmem_cache_alloc_trace+0x664/0xed0
  init_memory_block+0x8c/0x170
  create_memory_block_devices+0xa4/0x150
  add_memory_resource+0x188/0x530
  __add_memory+0x78/0x104
  add_memory+0x6c/0xb0

David Hildenbrand (1):
  mm/memory_hotplug: extend offline_and_remove_memory() to handle more
    than one memory block

 mm/memory_hotplug.c | 105 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 89 insertions(+), 16 deletions(-)

-- 
2.25.1