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Following 4 patches address issues with lockdep, particularly around bd_mutex. They are against 2.6.18-mm3 and do *not* apply against -linus as -mm already has some changes to the handling of bd_mutex nesting. 2-4 probably apply on top of -linus plus -mm/broken-out/remove-the-old-bd_mutex-lockdep-annotation.patch I believe they are probably ok for 2.6.19. The core issue is that blkdev_get when called on a partition needs to lock (bd_mutex) the partition and the whole device. lockdep would normally see this as a possible deadlock and needs to be told that this particular nesting is known to be safe. The code to do this is in -linus is rather messy, largely because the locking itself is messy. The bd_mutex for the whole is taken several times while bd_mutex for the partition is held, and it is taken at both levels of the recursion (blkdev_get calls blkdev_get - only to one level). As key observation to simplifying the locking is to observer that a lot of the locking is there to protect the updating of bd_part_count. If those updates are moved, the locking can become simpler. The first patch removes the current approach in -mm to handling this nesting and explains why it is not ideal. This reverts new-bd_mutex-lockdep-annotation.patch The second simplifies the locking as explained above. The third adds the mutex_lock_nested annotations, which are now trivial. The last fixes a tangentially related lockdep problem in md - there is a false relationship between bd_mutex and md->reconfig_mutex which needs to be clarified. [PATCH 000 of 4] Introduction [PATCH 001 of 4] Remove lock_key approach to managing nested bd_mutex locks. [PATCH 002 of 4] Simplify some aspects of bd_mutex nesting. [PATCH 003 of 4] Use mutex_lock_nested for bd_mutex to avoid lockdep warning. [PATCH 004 of 4] Avoid lockdep warning in md. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | |||||||||
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