From: David Hildenbrand <da...@redhat.com>

[ Upstream commit 5666848774ef43d3db5151ec518f1deb63515c20 ]

Let's perform all checking + offlining + removing under
device_hotplug_lock, so nobody can mess with these devices via sysfs
concurrently.

[da...@redhat.com: take device_hotplug_lock outside of loop]
  Link: http://lkml.kernel.org/r/20180927092554.13567-6-da...@redhat.com
Link: http://lkml.kernel.org/r/20180925091457.28651-6-da...@redhat.com
Signed-off-by: David Hildenbrand <da...@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatas...@microsoft.com>
Reviewed-by: Rashmica Gupta <rashmic...@gmail.com>
Acked-by: Balbir Singh <bsinghar...@gmail.com>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Rashmica Gupta <rashmic...@gmail.com>
Cc: Michael Neuling <mi...@neuling.org>
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Haiyang Zhang <haiya...@microsoft.com>
Cc: Heiko Carstens <heiko.carst...@de.ibm.com>
Cc: John Allen <jal...@linux.vnet.ibm.com>
Cc: Jonathan Corbet <cor...@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo....@lge.com>
Cc: Juergen Gross <jgr...@suse.com>
Cc: Kate Stewart <kstew...@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <k...@microsoft.com>
Cc: Len Brown <l...@kernel.org>
Cc: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Mathieu Malaterre <ma...@debian.org>
Cc: Michal Hocko <mho...@suse.com>
Cc: Nathan Fontenot <nf...@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalva...@suse.de>
Cc: Philippe Ombredanne <pombreda...@nexb.com>
Cc: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
Cc: Stephen Hemminger <sthem...@microsoft.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vlastimil Babka <vba...@suse.cz>
Cc: YASUAKI ISHIMATSU <yasu.isim...@gmail.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 arch/powerpc/platforms/powernv/memtrace.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/memtrace.c 
b/arch/powerpc/platforms/powernv/memtrace.c
index a29fdf8a2e56e..232bf5987f91d 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -70,6 +70,7 @@ static int change_memblock_state(struct memory_block *mem, 
void *arg)
        return 0;
 }
 
+/* called with device_hotplug_lock held */
 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
 {
        u64 end_pfn = start_pfn + nr_pages - 1;
@@ -110,6 +111,7 @@ static u64 memtrace_alloc_node(u32 nid, u64 size)
        /* Trace memory needs to be aligned to the size */
        end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 
+       lock_device_hotplug();
        for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
                if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
                        /*
@@ -118,7 +120,6 @@ static u64 memtrace_alloc_node(u32 nid, u64 size)
                         * we never try to remove memory that spans two iomem
                         * resources.
                         */
-                       lock_device_hotplug();
                        end_pfn = base_pfn + nr_pages;
                        for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> 
PAGE_SHIFT) {
                                remove_memory(nid, pfn << PAGE_SHIFT, bytes);
@@ -127,6 +128,7 @@ static u64 memtrace_alloc_node(u32 nid, u64 size)
                        return base_pfn << PAGE_SHIFT;
                }
        }
+       unlock_device_hotplug();
 
        return 0;
 }
-- 
2.20.1

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