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 <[email protected]> Cc: Toshi Kani <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Logan Gunthorpe <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Reported-by: Ben Hutchings <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- 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 bd684fc8ec1d..a48a7ff70164 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -1139,6 +1139,7 @@ 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 19b460acb5e1..0ab3dd6cc2a4 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();
