bdi: lockdep warning in bdi_queue_work

From: Sasha Levin
Date: Fri Apr 04 2014 - 18:06:56 EST


Hi all,

While fuzzing with trinity inside a KVM tools guest running the latest -next
kernel I've stumbled on the following:

[ 323.192041] INFO: trying to register non-static key.
[ 323.193083] the code is fine but needs lockdep annotation.
[ 323.193949] turning off the locking correctness validator.
[ 323.194687] CPU: 15 PID: 21793 Comm: trinity-c94 Not tainted 3.14.0-next-20140403-sasha-00019-g7474aa9-dirty #376
[ 323.196300] 0000000000000000 ffff8804d9067cf8 ffffffff954bfb2f 0000000000000000
[ 323.197522] ffffffff99378b10 ffff8804d9067df8 ffffffff921c3912 ffff88082bddaeb0
[ 323.198879] ffff880800000000 ffff880400000001 ffffffff00000000 ffff8804d9067d48
[ 323.200063] Call Trace:
[ 323.200487] dump_stack (lib/dump_stack.c:52)
[ 323.200581] __lock_acquire (kernel/locking/lockdep.c:743 kernel/locking/lockdep.c:3078)
[ 323.200581] ? __slab_alloc (mm/slub.c:2385 (discriminator 2))
[ 323.200581] ? __lock_acquire (kernel/locking/lockdep.c:3189)
[ 323.200581] ? kvm_clock_read (arch/x86/include/asm/preempt.h:90 arch/x86/kernel/kvmclock.c:86)
[ 323.200581] lock_acquire (arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602)
[ 323.200581] ? bdi_queue_work (arch/x86/include/asm/bitops.h:313 fs/fs-writeback.c:108)
[ 323.200581] _raw_spin_lock_bh (include/linux/spinlock_api_smp.h:136 kernel/locking/spinlock.c:175)
[ 323.200581] ? bdi_queue_work (arch/x86/include/asm/bitops.h:313 fs/fs-writeback.c:108)
[ 323.200581] bdi_queue_work (arch/x86/include/asm/bitops.h:313 fs/fs-writeback.c:108)
[ 323.200581] __bdi_start_writeback (fs/fs-writeback.c:141)
[ 323.200581] wakeup_flusher_threads (fs/fs-writeback.c:1077)
[ 323.200581] ? wakeup_flusher_threads (include/linux/rcupdate.h:800 fs/fs-writeback.c:1076)
[ 323.200581] ? syscall_trace_enter (include/linux/context_tracking.h:27 arch/x86/kernel/ptrace.c:1461)
[ 323.200581] sys_sync (fs/sync.c:107)
[ 323.200581] tracesys (arch/x86/kernel/entry_64.S:749)


Thanks,
Sasha
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