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    SubjectRe: [tip:core/locking] lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()
    On Tue, 6 Dec 2011, tip-bot for Yong Zhang wrote:

    > Commit-ID: d3d03d4fc5b1bec3a579112de170a9676e9d97cb
    > Gitweb: http://git.kernel.org/tip/d3d03d4fc5b1bec3a579112de170a9676e9d97cb
    > Author: Yong Zhang <yong.zhang0@gmail.com>
    > AuthorDate: Wed, 9 Nov 2011 16:04:51 +0800
    > Committer: Ingo Molnar <mingo@elte.hu>
    > CommitDate: Tue, 6 Dec 2011 08:16:51 +0100
    >
    > lockdep, kmemcheck: Annotate ->lock in lockdep_init_map()
    >
    > Since commit f59de89 ("lockdep: Clear whole lockdep_map on initialization"),
    > lockdep_init_map() will clear all the struct. But it will break
    > lock_set_class()/lock_set_subclass(). A typical race condition
    > is like below:
    >
    > CPU A CPU B
    > lock_set_subclass(lockA);
    > lock_set_class(lockA);
    > lockdep_init_map(lockA);
    > /* lockA->name is cleared */
    > memset(lockA);
    > __lock_acquire(lockA);
    > /* lockA->class_cache[] is cleared */
    > register_lock_class(lockA);
    > look_up_lock_class(lockA);
    > WARN_ON_ONCE(class->name !=
    > lock->name);
    >
    > lock->name = name;
    >
    > So restore to what we have done before commit f59de89 but annotate
    > ->lock with kmemcheck_mark_initialized() to suppress the kmemcheck
    > warning reported in commit f59de89.
    >
    > Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
    > Reported-by: Borislav Petkov <bp@alien8.de>
    > Suggested-by: Vegard Nossum <vegard.nossum@gmail.com>
    > Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
    > Cc: Tejun Heo <tj@kernel.org>
    > Cc: David Rientjes <rientjes@google.com>

    Acked-by: David Rientjes <rientjes@google.com>

    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > Link: http://lkml.kernel.org/r/20111109080451.GB8124@zhy
    > Signed-off-by: Ingo Molnar <mingo@elte.hu>


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