[PATCH v3 6/6] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done

From: Jia He <justin.he@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Tony Luck <tony.luck@intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	David Hildenbrand <david@redhat.com>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Baoquan He <bhe@redhat.com>, Chuhong Yuan <hslester96@gmail.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Hocko <mhocko@suse.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-sh@vger.kernel.org, linux-nvdimm@lists.01.org,
	linux-mm@kvack.org,
	Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
	Kaly Xin <Kaly.Xin@arm.com>, Jia He <justin.he@arm.com>,
	stable@vger.kernel.org
Subject: [PATCH v3 6/6] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done
Date: Thu,  9 Jul 2020 10:06:29 +0800	[thread overview]
Message-ID: <20200709020629.91671-7-justin.he@arm.com> (raw)
In-Reply-To: <20200709020629.91671-1-justin.he@arm.com>

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>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Dan Williams <dan.j.williams@intel.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 b49ab743d914..3e0645387daf 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1752,7 +1752,7 @@ 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");
@@ -1776,9 +1776,8 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 
 	try_offline_node(nid);
 
-done:
 	mem_hotplug_done();
-	return rc;
+	return 0;
 }
 
 /**
-- 
2.17.1

