Re: [PATCH v2 3/3] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done

David Hildenbrand
2020-07-07T11:31:40Z

On 07.07.20 07:59, Jia He wrote:
> When check_memblock_offlined_cb() returns failed rc(e.g. the memblock is
> online at that time), mem_hotplug_begin/done is unpaired in such case.
>
> Therefore a warning:
> Call Trace:
> percpu_up_write+0x33/0x40
> try_remove_memory+0x66/0x120
> ? _cond_resched+0x19/0x30
> remove_memory+0x2b/0x40
> dev_dax_kmem_remove+0x36/0x72 [kmem]
> device_release_driver_internal+0xf0/0x1c0
> device_release_driver+0x12/0x20
> bus_remove_device+0xe1/0x150
> device_del+0x17b/0x3e0
> unregister_dev_dax+0x29/0x60
> devm_action_release+0x15/0x20
> release_nodes+0x19a/0x1e0
> devres_release_all+0x3f/0x50
> device_release_driver_internal+0x100/0x1c0
> driver_detach+0x4c/0x8f
> bus_remove_driver+0x5c/0xd0
> driver_unregister+0x31/0x50
> dax_pmem_exit+0x10/0xfe0 [dax_pmem]
>
> Fixes: f1037ec0cc8a ("mm/memory_hotplug: fix remove_memory() lockdep splat")
> Cc: stable@vger.kernel.org # v5.6+
> Signed-off-by: Jia He <justin.he@arm.com>
> ---
> mm/memory_hotplug.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index da374cd3d45b..76c75a599da3 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1742,7 +1742,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
> */
> rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
> if (rc)
> - goto done;
> + return rc;
>
> /* remove memmap entry */
> firmware_map_remove(start, start + size, "System RAM");
> @@ -1766,9 +1766,8 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>
> try_offline_node(nid);
>
> -done:
> mem_hotplug_done();
> - return rc;
> + return 0;
> }
>
> /**
>

Reviewed-by: David Hildenbrand <david@redhat.com>

--
Thanks,

David / dhildenb