Re: VFS deadlock ?
From: Linus Torvalds
Date: Thu Mar 21 2013 - 17:18:21 EST
On Thu, Mar 21, 2013 at 2:02 PM, Dave Jones <davej@xxxxxxxxxx> wrote:
> here we go...
> WARNING: at fs/namei.c:2335 lock_rename+0x156/0x160()
> p1=irda p2=irda
Ok, good. I ssupect it's /proc or /sys, we do have that entry there.
But in fact I suspect we do want the parent name after all, because I
think we have multiple "irda" directories. There's the one in
/proc/net/ (added by net/irda/irproc.c), and there's a sysctl CTL_DIR
"irda" directory (kernel/sysctl_binary.c). And there might even be a
few other ones in /sys too, thanks to the ldisc called "irda" etc.
I don't see where the shared inode comes from, but I suspect that
would be easier to guess if we actually see which particular case it
ends up being..
> followed by...
> [ BUG: bad unlock balance detected! ]
Oh, ok, that's just because the unlock path doesn't have the same
logic for unlocking identical inodes that the thing just added to the
locking path. You'd need to add a check for "same inode" and only
unlock it once.
So that was my fault in asking for a non-BUG_ON and not doing the
complete thing. See "unlock_rename()" - you'd need to change the "p1
!= p2" test there to "p1->d_inode != p2->d_inode" there to match the
logic in lock_rename()
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