The patch titled
lockdep: avoid lockdep warning in md
has been added to the -mm tree. Its filename is
avoid-lockdep-warning-in-md.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: lockdep: avoid lockdep warning in md
From: NeilBrown <neilb@xxxxxxx>
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 <mingo@xxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
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
@@ -4423,7 +4423,7 @@ 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
/*
_
Patches currently in -mm which might be from neilb@xxxxxxx are
origin.patch
vfs-destroy-the-dentries-contributed-by-a-superblock-on-unmounting.patch
md-use-build_bug_on.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets-tidy.patch
remove-lock_key-approach-to-managing-nested-bd_mutex-locks.patch
simplify-some-aspects-of-bd_mutex-nesting.patch
use-mutex_lock_nested-for-bd_mutex-to-avoid-lockdep-warning.patch
avoid-lockdep-warning-in-md.patch
knfsd-add-nfs-export-support-to-tmpfs.patch
md-conditionalize-some-code.patch
md-dm-reduce-stack-usage-with-stacked-block-devices.patch
-
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