Messages in this thread | | | Date | Fri, 10 Oct 2008 14:51:44 +0300 | From | Eduard - Gabriel Munteanu <> | Subject | Re: [PROBLEM] hard-lock with kmemtrace, relayfs, and splice |
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On Fri, Oct 10, 2008 at 12:42:03PM +0300, Pekka Enberg wrote: > (I'm cc'ing Tom, Jens, and LKML.) > > On Fri, 2008-10-10 at 12:10 +0300, Pekka Enberg wrote: > > > I'm seeing a hard lock on my machine when I run kmemtraced with the > > > following patch applied: > > > > > > http://git.kernel.org/?p=linux/kernel/git/penberg/slab-2.6.git;a=commitdiff;h=17ca1d5506b1db433f0b7167a627bfd55d319dd3 > > > > > > I can enable/disable kmemtrace via the debugfs files fine and can also > > > read the relay files with cat. > > > > > > Any idea where this is coming from? > > > > OK, it's the first splice() call in reader_thread() that causes the > > hang. Hmm. > > To recap, with a CONFIG_KMEMTRACE enabled kernel from the > "topic/kmemtrace" branch of: > > git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6.git topic/kmemtrace > > running the "kmemtraced" program from > > git://git.kernel.org/pub/scm/linux/kernel/git/penberg/kmemtrace-user.git > > results to a hard lock on my machine. I am unable to find anything > obviously wrong with it and as I can read/write the relay files just > fine, I'm beginning to think it's problem in relayfs splice > implementation. > > Tom, thoughts? > > Pekka >
Hmm, I've seen kmemtraced not stopping, but no hard locks. It seems not even SIGKILL can stop it. As far as I know, SIGKILL should stop even a blocking splice() (in case this is the problem). This is what I did: # ./kmemtraced & # killall -KILL kmemtraced ... kmemtraced still running and using CPU.
Eduard
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