Re: processes hung after sys_renameat, and 'missing' processes

From: Al Viro
Date: Sun Jun 03 2012 - 19:40:40 EST


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.
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