Re: [BUG] 2.4.x RT signal leak with kupdated (and maybe others)
From: Andrea Arcangeli (andrea_at_suse.de)
Date: 09/30/03
- Previous message: linas_at_austin.ibm.com: "Re: [2.4 PATCH:] Lengthen SCSI timeouts to deal with broken hardware"
- In reply to: Benjamin Herrenschmidt: "Re: [BUG] 2.4.x RT signal leak with kupdated (and maybe others)"
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Date: Tue, 30 Sep 2003 20:22:55 +0200 To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
On Tue, Sep 30, 2003 at 07:47:09PM +0200, Benjamin Herrenschmidt wrote:
> > When I wrote the kupdate code, only the real time signals could be
> > queued. Now things have changed to carry the siginfo for non-RT too. The
> > fact we clear the pending by hand is what allows more than a RT signal
> > to be stacked, we shouldn't clear the bitflag unless we dequeue the
> > signal too. That's definitely a bug (though a minor one ;)
>
> "Minor" but leads to interesting results in the end when coupled
> with something like noflushd that regulary send those signals ;)
>
> Not only we leak them, but we also get nr_queued_signals reaching
> nr_max_signals. This has the side effect of making do_notify_parent()
> silently fail when a pthread is dead (libpthread use an RT signal).
>
> The end result is that after a few days, a machine running noflushd
> and thread intensive apps like evolution and gkrellm will have dozens
> (or even hundreds) of zombies as the child threads are never reclaimed
> by libpthread "manager" thread since it never gets the signal...
for noflushd users it's major (for everybody else is minor)
> Interesting... though hopefully, I didn't see anybody else causing
> such a constant increase of nr_queued_signals so far on this laptop...
That's because nobody else sends signals to the daemons I guess. And
even if they do the daemon won't clear the pending bitflag, so there's
no risk to queue more than 1 non-RT entry per signal per daemon like it
happened with kupdate.
Andrea - If you prefer relying on open source software, check these links:
rsync.kernel.org::pub/scm/linux/kernel/bkcvs/linux-2.[45]/
http://www.cobite.com/cvsps/
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- Previous message: linas_at_austin.ibm.com: "Re: [2.4 PATCH:] Lengthen SCSI timeouts to deal with broken hardware"
- In reply to: Benjamin Herrenschmidt: "Re: [BUG] 2.4.x RT signal leak with kupdated (and maybe others)"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
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