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Subject[PATCH v1] ACPI / scan: Acquire device_hotplug_lock in acpi_scan_init()
Date
We end up calling __add_memory() without the device hotplug lock held.
(I used a local patch to assert in __add_memory() that the
device_hotplug_lock is held - I might upstream that as well soon)

[ 26.771684] create_memory_block_devices+0xa4/0x140
[ 26.772952] add_memory_resource+0xde/0x200
[ 26.773987] __add_memory+0x6e/0xa0
[ 26.775161] acpi_memory_device_add+0x149/0x2b0
[ 26.776263] acpi_bus_attach+0xf1/0x1f0
[ 26.777247] acpi_bus_attach+0x66/0x1f0
[ 26.778268] acpi_bus_attach+0x66/0x1f0
[ 26.779073] acpi_bus_attach+0x66/0x1f0
[ 26.780143] acpi_bus_scan+0x3e/0x90
[ 26.780844] acpi_scan_init+0x109/0x257
[ 26.781638] acpi_init+0x2ab/0x30d
[ 26.782248] do_one_initcall+0x58/0x2cf
[ 26.783181] kernel_init_freeable+0x1bd/0x247
[ 26.784345] kernel_init+0x5/0xf1
[ 26.785314] ret_from_fork+0x3a/0x50

So perform the locking just like in acpi_device_hotplug().

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
drivers/acpi/scan.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 0e28270b0fd8..cbc9d64b48dd 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2204,7 +2204,9 @@ int __init acpi_scan_init(void)
acpi_gpe_apply_masked_gpes();
acpi_update_all_gpes();

+ lock_device_hotplug();
mutex_lock(&acpi_scan_lock);
+
/*
* Enumerate devices in the ACPI namespace.
*/
@@ -2232,6 +2234,7 @@ int __init acpi_scan_init(void)

out:
mutex_unlock(&acpi_scan_lock);
+ unlock_device_hotplug();
return result;
}

--
2.21.0
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