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From: Peter Zijlstra on 11 Jun 2010 03:20 On Wed, 2010-06-02 at 15:04 +0200, Jens Axboe wrote: > On Wed, Jun 02 2010, Ingo Molnar wrote: > > > > btw., there's another warning triggered by the new blk-cgroups stats code: > > > > sda:INFO: trying to register non-static key. > > the code is fine but needs lockdep annotation. > > turning off the locking correctness validator. > > Pid: 81, comm: async/2 Not tainted 2.6.35-rc1-tip-01073-gd2f7698-dirty #6765 > > Call Trace: > > [<ffffffff81065d6d>] register_lock_class+0x15f/0x365 > > [<ffffffff8105c426>] ? sched_clock_local+0x1d/0x83 > > [<ffffffff8105c557>] ? sched_clock_cpu+0xcb/0xd9 > > [<ffffffff81067184>] __lock_acquire+0x97/0x481 > > [<ffffffff810088d4>] ? native_sched_clock+0x37/0x6d > > [<ffffffff81321b74>] ? blkiocg_update_io_add_stats+0x32/0x12e > > [<ffffffff81067644>] lock_acquire+0xd6/0xfd > > [<ffffffff81321b74>] ? blkiocg_update_io_add_stats+0x32/0x12e > > [<ffffffff81850859>] _raw_spin_lock_irqsave+0x47/0x82 > > [<ffffffff81321b74>] ? blkiocg_update_io_add_stats+0x32/0x12e > > [<ffffffff81321b74>] blkiocg_update_io_add_stats+0x32/0x12e > > So that's blkg->stats_lock - help me out, what is lockdep complaining > about? The lock is initialized, what kind of lockdep annotation magic do > we need to sprinkle on it? It basically says its lock instance isn't properly initialised. Usually spin_lock_init() will set lock->dep_map->key, for static locks, initialised with __SPIN_LOCK_UNLOCKED() ->key doesn't get set and we use the lock's address as key. Now lockdep requires the key to be in static storage, so if you try to used __SPIN_LOCK_UNLOCKED() on dynamically allocated locks (the most common form is using static forms like DEFINE_foo() on stack variables), things go bang. That said, the block_cgroup.c code seems to use spin_lock_init() so it _should_ all work out. Use before init/after free perhaps? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |