From: NeilBrown md_open takes ->reconfig_mutex which causes lockdep to complain. This (normally) doesn't have deadlock potential as the possible conflict is with a reconfig_mutex in a different device. I say "normally" because if a loop were created in the array->member hierarchy a deadlock could happen. However that causes bigger problems than a deadlock and should be fixed independently. So we flag the lock in md_open as a nested lock. This requires defining mutex_lock_interruptible_nested. Cc: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- drivers/md/md.c | 2 +- include/linux/mutex.h | 2 ++ kernel/mutex.c | 9 +++++++++ 3 files changed, 12 insertions(+), 1 deletion(-) diff -puN drivers/md/md.c~avoid-lockdep-warning-in-md drivers/md/md.c --- a/drivers/md/md.c~avoid-lockdep-warning-in-md +++ a/drivers/md/md.c @@ -4422,7 +4422,7 @@ static int md_open(struct inode *inode, mddev_t *mddev = inode->i_bdev->bd_disk->private_data; int err; - if ((err = mddev_lock(mddev))) + if ((err = mutex_lock_interruptible_nested(&mddev->reconfig_mutex, 1))) goto out; err = 0; diff -puN include/linux/mutex.h~avoid-lockdep-warning-in-md include/linux/mutex.h --- a/include/linux/mutex.h~avoid-lockdep-warning-in-md +++ a/include/linux/mutex.h @@ -125,8 +125,10 @@ extern int fastcall mutex_lock_interrupt #ifdef CONFIG_DEBUG_LOCK_ALLOC extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); +extern int mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass); #else # define mutex_lock_nested(lock, subclass) mutex_lock(lock) +# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) #endif /* diff -puN kernel/mutex.c~avoid-lockdep-warning-in-md kernel/mutex.c --- a/kernel/mutex.c~avoid-lockdep-warning-in-md +++ a/kernel/mutex.c @@ -206,6 +206,15 @@ mutex_lock_nested(struct mutex *lock, un } EXPORT_SYMBOL_GPL(mutex_lock_nested); + +int __sched +mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) +{ + might_sleep(); + return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass); +} + +EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); #endif /* _