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Subject[PATCH AUTOSEL 4.19 005/100] powerpc/powernv: hold device_hotplug_lock when calling memtrace_offline_pages()
Date
From: David Hildenbrand <david@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.

[david@redhat.com: take device_hotplug_lock outside of loop]
Link: http://lkml.kernel.org/r/20180927092554.13567-6-david@redhat.com
Link: http://lkml.kernel.org/r/20180925091457.28651-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@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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