From 3fc21924100b13f73c734d0ce8dfcfe913fcf7a8 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 24 Feb 2017 14:55:48 -0800 Subject: [PATCH] mm: validate device_hotplug is held for memory hotplug 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. Link: http://lkml.kernel.org/r/148693886229.16345.1770484669403334689.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Ben Hutchings Cc: Michal Hocko Cc: Toshi Kani Cc: Vlastimil Babka Cc: Logan Gunthorpe Cc: Greg Kroah-Hartman Cc: Masayoshi Mizuma Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 8c25e68..3050e6f 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 bd684fc..a48a7ff 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 d67787d..92a242a 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(); -- 2.7.4