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mm: validate device_hotplug is held for memory hotplug

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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 <dan.j.williams@intel.com>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2017-02-24 14:55:48 -08:00 committed by Linus Torvalds
parent b5d24fda9c
commit 3fc2192410
3 changed files with 8 additions and 0 deletions
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5
drivers/base/core.c
View file

@ -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)
{

1
include/linux/device.h
View file

@ -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);

2
mm/memory_hotplug.c
View file

@ -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();