From: Jia He justin.he@arm.com Subject: mm/memory_hotplug: fix unpaired mem_hotplug_begin/done

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]

Link: http://lkml.kernel.org/r/20200710031619.18762-3-justin.he@arm.com Fixes: f1037ec0cc8a ("mm/memory_hotplug: fix remove_memory() lockdep splat") Signed-off-by: Jia He justin.he@arm.com Reviewed-by: David Hildenbrand david@redhat.com Acked-by: Michal Hocko mhocko@suse.com Acked-by: Dan Williams dan.j.williams@intel.com Cc: stable@vger.kernel.org [5.6+] Cc: Andy Lutomirski luto@kernel.org Cc: Baoquan He bhe@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Catalin Marinas catalin.marinas@arm.com Cc: Chuhong Yuan hslester96@gmail.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Dave Jiang dave.jiang@intel.com Cc: Fenghua Yu fenghua.yu@intel.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: Jonathan Cameron Jonathan.Cameron@Huawei.com Cc: Kaly Xin Kaly.Xin@arm.com Cc: Logan Gunthorpe logang@deltatee.com Cc: Masahiro Yamada masahiroy@kernel.org Cc: Mike Rapoport rppt@linux.ibm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Rich Felker dalias@libc.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Tony Luck tony.luck@intel.com Cc: Vishal Verma vishal.l.verma@intel.com Cc: Will Deacon will@kernel.org Cc: Yoshinori Sato ysato@users.sourceforge.jp Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory_hotplug.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/mm/memory_hotplug.c~mm-memory_hotplug-fix-unpaired-mem_hotplug_begin-done +++ a/mm/memory_hotplug.c @@ -1757,7 +1757,7 @@ static int __ref try_remove_memory(int n */ 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"); @@ -1781,9 +1781,8 @@ static int __ref try_remove_memory(int n

try_offline_node(nid);

-done: mem_hotplug_done(); - return rc; + return 0; }

/** _