lkml.org 
[lkml]   [2011]   [Aug]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH v2] lockdep: Add helper function for dir vs file i_mutex annotation
    Purely in-memory filesystems do not use the inode hash as the dcache tells
    us if an entry already exists. As a result, they do not call
    unlock_new_inode. If CONFIG_DEBUG_LOCK_ALLOC is set, this can lead to
    false positives from lockdep like below:

    | find/645 is trying to acquire lock:
    | (&mm->mmap_sem){++++++}, at: [<ffffffff81109514>] might_fault+0x5c/0xac
    |
    | but task is already holding lock:
    | (&sb->s_type->i_mutex_key#15){+.+.+.}, at: [<ffffffff81149f34>]
    | vfs_readdir+0x5b/0xb4
    |
    | which lock already depends on the new lock.
    |
    | the existing dependency chain (in reverse order) is:
    |
    | -> #1 (&sb->s_type->i_mutex_key#15){+.+.+.}:
    | [<ffffffff8108ac26>] lock_acquire+0xbf/0x103
    | [<ffffffff814db822>] __mutex_lock_common+0x4c/0x361
    | [<ffffffff814dbc46>] mutex_lock_nested+0x40/0x45
    | [<ffffffff811daa87>] hugetlbfs_file_mmap+0x82/0x110
    | [<ffffffff81111557>] mmap_region+0x258/0x432
    | [<ffffffff811119dd>] do_mmap_pgoff+0x2ac/0x306
    | [<ffffffff81111b4f>] sys_mmap_pgoff+0x118/0x16a
    | [<ffffffff8100c858>] sys_mmap+0x22/0x24
    | [<ffffffff814e3ec2>] system_call_fastpath+0x16/0x1b
    |
    | -> #0 (&mm->mmap_sem){++++++}:
    | [<ffffffff8108a4bc>] __lock_acquire+0xa1a/0xcf7
    | [<ffffffff8108ac26>] lock_acquire+0xbf/0x103
    | [<ffffffff81109541>] might_fault+0x89/0xac
    | [<ffffffff81149cff>] filldir+0x6f/0xc7
    | [<ffffffff811586ea>] dcache_readdir+0x67/0x205
    | [<ffffffff81149f54>] vfs_readdir+0x7b/0xb4
    | [<ffffffff8114a073>] sys_getdents+0x7e/0xd1
    | [<ffffffff814e3ec2>] system_call_fastpath+0x16/0x1b

    This moves the directory vs file lockdep annotation into a helper function
    that can be called by in-memory filesystems and has hugetlbfs call it.

    Signed-off-by: Josh Boyer <jwboyer@redhat.com>
    ---
    v2: Make the helper an empty inline in the non-debug case to cleanup some ifdefs

    fs/hugetlbfs/inode.c | 1 +
    fs/inode.c | 24 +++++++++++++++---------
    include/linux/fs.h | 5 +++++
    3 files changed, 21 insertions(+), 9 deletions(-)

    diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
    index 87b6e04..ec88953 100644
    --- a/fs/hugetlbfs/inode.c
    +++ b/fs/hugetlbfs/inode.c
    @@ -491,6 +491,7 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
    inode->i_op = &page_symlink_inode_operations;
    break;
    }
    + lockdep_annotate_inode_mutex_key(inode);
    }
    return inode;
    }
    diff --git a/fs/inode.c b/fs/inode.c
    index 73920d5..ec79246 100644
    --- a/fs/inode.c
    +++ b/fs/inode.c
    @@ -848,16 +848,9 @@ struct inode *new_inode(struct super_block *sb)
    }
    EXPORT_SYMBOL(new_inode);

    -/**
    - * unlock_new_inode - clear the I_NEW state and wake up any waiters
    - * @inode: new inode to unlock
    - *
    - * Called when the inode is fully initialised to clear the new state of the
    - * inode and wake up anyone waiting for the inode to finish initialisation.
    - */
    -void unlock_new_inode(struct inode *inode)
    -{
    #ifdef CONFIG_DEBUG_LOCK_ALLOC
    +void lockdep_annotate_inode_mutex_key(struct inode *inode)
    +{
    if (S_ISDIR(inode->i_mode)) {
    struct file_system_type *type = inode->i_sb->s_type;

    @@ -873,7 +866,20 @@ void unlock_new_inode(struct inode *inode)
    &type->i_mutex_dir_key);
    }
    }
    +}
    +EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
    #endif
    +
    +/**
    + * unlock_new_inode - clear the I_NEW state and wake up any waiters
    + * @inode: new inode to unlock
    + *
    + * Called when the inode is fully initialised to clear the new state of the
    + * inode and wake up anyone waiting for the inode to finish initialisation.
    + */
    +void unlock_new_inode(struct inode *inode)
    +{
    + lockdep_annotate_inode_mutex_key(inode);
    spin_lock(&inode->i_lock);
    WARN_ON(!(inode->i_state & I_NEW));
    inode->i_state &= ~I_NEW;
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index 178cdb4..c2bd68f 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -2318,6 +2318,11 @@ extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*te
    extern struct inode * iget_locked(struct super_block *, unsigned long);
    extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
    extern int insert_inode_locked(struct inode *);
    +#ifdef CONFIG_DEBUG_LOCK_ALLOC
    +extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
    +#else
    +static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };
    +#endif
    extern void unlock_new_inode(struct inode *);
    extern unsigned int get_next_ino(void);

    --
    1.7.6


    \
     
     \ /
      Last update: 2011-08-25 13:51    [W:0.031 / U:90.676 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site