Re: VFS deadlock ?

From: Al Viro
Date: Thu Mar 21 2013 - 17:26:26 EST


On Thu, Mar 21, 2013 at 02:18:15PM -0700, Linus Torvalds wrote:
> 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..

Well, something like
static char path[4096];
d_absolute_path(p1, path, 4096);
printk(KERN_ERR "%s %s %d %d"
path, p1->d_sb->s_type->name, d_unlinked(p1), d_unlinked(p2));
might be useful - pathname within fs, fs type and which of those suckers are
unlinked...
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