mem_hotplug_begin() assumes that it can set mem_hotplug.active_writer
and run the hotplug process without racing another thread. Validate this
assumption with a lockdep assertion.
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/base/core.c | 5 +++++
include/linux/device.h | 1 +
mm/memory_hotplug.c | 2 ++
3 files changed, 8 insertions(+)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8c25e68e67d7..3050e6f99403 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -638,6 +638,11 @@ int lock_device_hotplug_sysfs(void)
return restart_syscall();
}
+void assert_held_device_hotplug(void)
+{
+ lockdep_assert_held(&device_hotplug_lock);
+}
+
#ifdef CONFIG_BLOCK
static inline int device_is_not_partition(struct device *dev)
{
diff --git a/include/linux/device.h b/include/linux/device.h
index 491b4c0ca633..815965ee55dd 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1135,6 +1135,7 @@ static inline bool device_supports_offline(struct device *dev)
extern void lock_device_hotplug(void);
extern void unlock_device_hotplug(void);
extern int lock_device_hotplug_sysfs(void);
+void assert_held_device_hotplug(void);
extern int device_offline(struct device *dev);
extern int device_online(struct device *dev);
extern void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b8c11e063ff0..1635a2a085e5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -126,6 +126,8 @@ void put_online_mems(void)
void mem_hotplug_begin(void)
{
+ assert_held_device_hotplug();
+
mem_hotplug.active_writer = current;
memhp_lock_acquire();
--
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