linux-kernel - 3.13.5 : rm -rf running forever, one cpu at approx 100%

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Message-ID: <20140227005246.GB10367@milliways>
Date:	Thu, 27 Feb 2014 00:52:46 +0000
From:	Ken Moffat <zarniwhoop@...world.com>
To:	linux-kernel@...r.kernel.org
Subject: 3.13.5 : rm -rf running forever, one cpu at approx 100%

Hi,

 Short summary : on 3.13.5, rm -rf of an application source
directory on an ext4 filesystem sometimes takes forever (probably
isn't going anywhere), with one CPU pegged at all-but 100% utilization.

 I've nearly finished building a new system from source, to check
various desktop packages in linuxfromscratch.  On this build, much of
it is things I don't normally use and I needed to upgrade my
buildscripts, so most of it was built in chroot using 3.10.32.  But
late last night I booted the new system using 3.13.5 to finish the
build.  This morning I discovered that rm -rf for the icedtea source
directory was still running, and had taken over 5 hours of CPU time
(one CPU seemd to be running at close to 100%, the others had dropped
to their slowest frequency).  That script was running as root (yeah,
but it's a new system) and it looks as if /etc/passwd~ had got
trashed, because I could no longer su or login.  Not sure if that is
related, at this stage it might just be a side-effect of my scripts.

 Booted another system, chrooted, fixed up passwords.  Started
again after commenting out icedtea - I hadn't intended to build
what was an old version, I'd just forgotten it was in this script -
that's why I do things in userspace, not the kernel :-(

 Continued with remaining packages, but a couple of hours later I
saw a similar "one CPU at 100%, rm -rf GConf source taking forever"
problem.  Dumped all the processes with Alt-SysRQ-T [ huge log ] but
at that point 'rm' was merely 'ready' so I doubt there is anything
useful to see in the log.

 Built 3.13.4, booted to that.  So far, everything looks good - but
I'm now building the _current_ version of icedtea, so if this isn't
a new 3.13.5 problem I guess I'm fairly likely to see it tomorrow.

 Meanwhile, any suggestions about how I can debug this if I hit it
again, please ?

ĸen
-- 
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