From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: Potentially unbounded allocations in seq_read?
Date: Thu, 12 Dec 2013 14:21:58 +0000
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Cc: Andrew Morton <akpm@linux-foundation.org>,
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To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
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On Thu, Dec 12, 2013 at 01:59:31PM +0000, Tvrtko Ursulin wrote:

> > a) *what* errors other than -ENAMETOOLONG?
> 
> Is this your way of saying there can't be any other errors from d_path?

Check yourself...  It is the only error that makes sense there and yes,
it is the only one being returned.

> > b) d_path() not fitting into 2Mb is definitely a bug.  If you really have
> > managed to get a dentry tree 1 million levels deep, you have much worse
> > problems.
> > c) which kernel version it is?
> 
> 3.10. I can't imagine this is an actual dentry tree somewhere, probably
> just a bug of some sort. I'll probably hunt it down completely some time
> next week, time permitting.

Sounds like missing backport of 118b23 ("cope with potentially long ->d_dname()
output for shmem/hugetlb").  It *is* in -stable (linux-3.10.y has it since
3.10.17 as commit ad4c3c), but if your tree doesn't have it, that's the one
to try first...