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    SubjectRe: 2.6.21 reiserfs -- cicular locking?
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    Jeff Mahoney wrote:
    > Takashi Iwai wrote:
    >>> At Fri, 27 Apr 2007 07:09:01 -0400,
    >>> Jeff Mahoney wrote:
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    >>>>
    >>>> Takashi Iwai wrote:
    >>>>> At Fri, 27 Apr 2007 12:09:03 +0200,
    >>>>> I wrote:
    >>>>>> I got a similar bug right now at the fresh boot of 2.6.21.
    >>>>>>
    >>>>>>
    >>>>>> ReiserFS: sda2: found reiserfs format "3.6" with standard journal
    >>>>>> ReiserFS: sda2: using ordered data mode
    >>>>>> ReiserFS: sda2: journal params: device sda2, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
    >>>>>> ReiserFS: sda2: checking transaction log (sda2)
    >>>>>> ReiserFS: sda2: Using r5 hash to sort names
    >>>>>> ReiserFS: sda2: Removing [3613 1354701 0x0 SD]..done
    >>>>>> ReiserFS: sda2: There were 1 uncompleted unlinks/truncates. Completed
    >>>>>>
    >>>>>> =======================================================
    >>>>>> [ INFO: possible circular locking dependency detected ]
    >>>>>> 2.6.21-work #1
    >>>>>> -------------------------------------------------------
    >>>>>> mktemp/1459 is trying to acquire lock:
    >>>>>> (&REISERFS_I(inode)->xattr_sem){..--}, at: [<e08a5236>] reiserfs_cache_default_acl+0x2a/0x9c [reiserfs]
    >>>>>>
    >>>>>> but task is already holding lock:
    >>>>>> (&inode->i_mutex){--..}, at: [<c016d7dc>] open_namei+0xe2/0x5a2
    >>>>>>
    >>>>>> which lock already depends on the new lock.
    >>>>> The message disappears when I revert the patch:
    >>>>>
    >>>>> commit 9b7f375505f5611efb562065b57814b28a81abc3
    >>>>> Author: Jeff Mahoney <jeffm@suse.com>
    >>>>> Date: Mon Apr 23 14:41:17 2007 -0700
    >>>>>
    >>>>> reiserfs: fix xattr root locking/refcount bug
    >>>>>
    >>>>>
    >>>>> So, likely a newly introduced bug after rc7...
    >>>> I got a message with a trace similar to this from Vladimir before I
    >>>> submitted that patch. I'm not sure how to annotate this, since the
    >>>> xattr_sem can never be taken in the manner described. Internal inodes
    >>>> are protected by I_PRIVATE.
    >>> Hm, then maybe my case was just a coincidence.
    >>>
    >>> FWIW, I can reproduce the deadlock warning at each time I boot
    >>> non-patched 2.6.21, and after reverting the patch, it disappeared.
    >
    > Ok, so I took another look at the report Vladimir sent me. The trace he
    > ran into was in the delete inode path, but was still a race between the
    > xattr_sem and the inode sem. Since we're locking the xattr root on the
    > xattr read path now, this condition arises more freqently, but it's
    > really the same one he reported.
    >
    > I'm using the default openSUSE config, which doesn't enable mutex
    > debugging. I'll rebuild with it, and hopefully come up with a way to
    > kill the warning.

    I still didn't get the warning, but can you try this and let me know
    if it fixes it?

    - -Jeff

    - --- a/fs/reiserfs/xattr.c 2007-04-22 10:53:10.000000000 -0400
    +++ b/fs/reiserfs/xattr.c 2007-04-27 12:09:02.000000000 -0400
    @@ -68,7 +68,7 @@
    if (!privroot)
    return ERR_PTR(-ENODATA);

    - - mutex_lock(&privroot->d_inode->i_mutex);
    + mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
    if (REISERFS_SB(sb)->xattr_root) {
    xaroot = dget(REISERFS_SB(sb)->xattr_root);
    goto out;
    - --
    Jeff Mahoney
    SUSE Labs
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    -
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