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    SubjectRe: processes hung after sys_renameat, and 'missing' processes
    On Mon, Jun 04, 2012 at 12:40:42AM +0100, Al Viro wrote:
    > On Mon, Jun 04, 2012 at 12:28:20AM +0100, Al Viro wrote:
    > > Everything in lock_rename() appears to be at lock_rename+0x3e. Unless
    > > there's a really huge amount of filesystems on that box, this has to
    > > be
    > > mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
    > > and everything on that sucker is not holding any locks yet. IOW, that's
    > > the tail hanging off whatever deadlock is there.
    > Er... After another look, probably not - it's ->s_vfs_rename_mutex,
    > so we are seeing one cross-directory rename stuck on something with
    > all subsequent ones blocked on attempt to grab said mutex.
    > The interesting one is the guy stuck at lock_rename+0xc9/0xf0, everything
    > else in lock_rename() is the consequence.

    BTW, another suspicious patch is d_splice_alias() one; note that if we
    _ever_ pick a dentry that isn't disconnected, we are deeply fucked.
    d_move() without the old parent locked is a Bad Thing(tm). I don't see
    how that could've triggered without another bug somewhere, but what's
    happening in d_splice_alias() right now is wrong.

     \ /
      Last update: 2012-06-04 02:21    [W:0.022 / U:8.312 seconds]
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